Merge branch 'fix-changelogs' into 'main'

[tor.git] / doc / man / tor.1.txt

// Copyright (c) The Tor Project, Inc.
// See LICENSE for licensing information
// This is an asciidoc file used to generate the manpage/html reference.
// Learn asciidoc on https://www.methods.co.nz/asciidoc/userguide.html
:man source:   Tor
:man manual:   Tor Manual
// compat-mode tells Asciidoctor tools to process this as legacy AsciiDoc
:compat-mode:
// attribute to make it easier to write names containing double underscores
:dbl_: __
= TOR(1)
:toc:

== NAME

tor - The second-generation onion router

== SYNOPSIS

**tor** [__OPTION__ __value__]...

== DESCRIPTION

Tor is a connection-oriented anonymizing communication service. Users
choose a source-routed path through a set of nodes, and negotiate a
"virtual circuit" through the network. Each node in a virtual circuit
knows its predecessor and successor nodes, but no other nodes. Traffic
flowing down the circuit is unwrapped by a symmetric key at each node,
which reveals the downstream node. +

Basically, Tor provides a distributed network of servers or relays
("onion routers").  Users bounce their TCP streams, including web
traffic, ftp, ssh, etc., around the network, so that recipients,
observers, and even the relays themselves have difficulty tracking the
source of the stream.

[NOTE]
By default, **tor** acts as a client only.  To help the network by
providing bandwidth as a relay, change the **ORPort** configuration
option as mentioned below.  Please also consult the documentation on
the Tor Project's website.

== COMMAND-LINE OPTIONS

Tor has a powerful command-line interface. This section lists optional
arguments you can specify at the command line using the **`tor`**
command.

Configuration options can be specified on the command line in the
format **`--`**_OptionName_ _OptionValue_, on the command line in the
format _OptionName_ _OptionValue_, or in a configuration file.  For
instance, you can tell Tor to start listening for SOCKS connections on
port 9999 by passing either **`--SocksPort 9999`** or **`SocksPort
9999`** on the command line, or by specifying **`SocksPort 9999`** in
the configuration file.  On the command line, quote option values that
contain spaces. For instance, if you want Tor to log all debugging
messages to **`debug.log`**, you must specify **`--Log "debug file
debug.log"`**.

NOTE: Configuration options on the command line override those in
configuration files.  See **<<conf-format,THE CONFIGURATION FILE
FORMAT>>** for more information.

The following options in this section are only recognized on the
**`tor`** command line, not in a configuration file.

[[opt-h]] **`-h`**, **`--help`**::
    Display a short help message and exit.

[[opt-f]] **`-f`**, **`--torrc-file`** __FILE__::
    Specify a new configuration file to contain further Tor configuration
    options, or pass *-* to make Tor read its configuration from standard
    input. (Default: **`@CONFDIR@/torrc`**, or **`$HOME/.torrc`** if
    that file is not found.)

[[opt-allow-missing-torrc]] **`--allow-missing-torrc`**::
    Allow the configuration file specified by **`-f`** to be missing,
    if the defaults-torrc file (see below) is accessible.

[[opt-defaults-torrc]] **`--defaults-torrc`** __FILE__::
    Specify a file in which to find default values for Tor options.  The
    contents of this file are overridden by those in the regular
    configuration file, and by those on the command line. (Default:
    **`@CONFDIR@/torrc-defaults`**.)

[[opt-ignore-missing-torrc]] **`--ignore-missing-torrc`**::
    Specify that Tor should treat a missing torrc file as though it
    were empty. Ordinarily, Tor does this for missing default torrc files,
    but not for those specified on the command line.

[[opt-hash-password]] **`--hash-password`** __PASSWORD__::
    Generate a hashed password for control port access.

[[opt-list-fingerprint]] **`--list-fingerprint`** [__key type__]::
    Generate your keys and output your nickname and fingerprint. Optionally,
    you can specify the key type as `rsa` (default) or `ed25519`.

[[opt-verify-config]] **`--verify-config`**::
    Verify whether the configuration file is valid.

[[opt-dump-config]] **`--dump-config`** **`short`**|**`full`**::
    Write a list of Tor's configured options to standard output.
    When the `short` flag is selected, only write the options that
    are different from their default values.
    When `full` is selected, write every option.

[[opt-serviceinstall]] **`--service install`** [**`--options`** __command-line options__]::
    Install an instance of Tor as a Windows service, with the provided
    command-line options. Current instructions can be found at
    https://www.torproject.org/docs/faq#NTService

[[opt-service]] **`--service`** **`remove`**|**`start`**|**`stop`**::
    Remove, start, or stop a configured Tor Windows service.

[[opt-nt-service]] **`--nt-service`**::
    Used internally to implement a Windows service.

[[opt-list-torrc-options]] **`--list-torrc-options`**::
    List all valid options.

[[opt-list-deprecated-options]] **`--list-deprecated-options`**::
    List all valid options that are scheduled to become obsolete in a
    future version. (This is a warning, not a promise.)

[[opt-list-modules]] **`--list-modules`**::
    List whether each optional module has been compiled into Tor.
    (Any module not listed is not optional in this version of Tor.)

[[opt-version]] **`--version`**::
    Display Tor version and exit. The output is a single line of the format
    "Tor version [version number]."  (The version number format
    is as specified in version-spec.txt.)

[[opt-quiet]] **`--quiet`**|**`--hush`**::
    Override the default console logging behavior.  By default, Tor
    starts out logging messages at level "notice" and higher to the
    console.  It stops doing so after it parses its configuration, if
    the configuration tells it to log anywhere else.  These options
    override the default console logging behavior.  Use the
    **`--hush`** option if you want Tor to log only warnings and
    errors to the console, or use the **`--quiet`** option if you want
    Tor not to log to the console at all.

[[opt-keygen]] **`--keygen`** [**`--newpass`**]::
    Running **`tor --keygen`** creates a new ed25519 master identity key
    for a relay, or only a fresh temporary signing key and
    certificate, if you already have a master key.  Optionally, you
    can encrypt the master identity key with a passphrase.  When Tor
    asks you for a passphrase and you don't want to encrypt the master
    key, just don't enter any passphrase when asked. +
     +
    Use the **`--newpass`** option with **`--keygen`** only when you
    need to add, change, or remove a passphrase on an existing ed25519
    master identity key. You will be prompted for the old passphrase
    (if any), and the new passphrase (if any).
+
[NOTE]
    When generating a master key, you may want to use
    **`--DataDirectory`** to control where the keys and certificates
    will be stored, and **`--SigningKeyLifetime`** to control their
    lifetimes.  See <<server-options,SERVER OPTIONS>> to learn more about the
    behavior of these options.  You must have write access to the
    specified DataDirectory.
+
[normal]
    To use the generated files, you must copy them to the
    __DataDirectory__/**`keys`** directory of your Tor daemon, and
    make sure that they are owned by the user actually running the Tor
    daemon on your system.

**`--passphrase-fd`** __FILEDES__::
    File descriptor to read the passphrase from.  Note that unlike with the
    tor-gencert program, the entire file contents are read and used as
    the passphrase, including any trailing newlines.
    If the file descriptor is not specified, the passphrase is read
    from the terminal by default.

[[opt-key-expiration]] **`--key-expiration`** [__purpose__] [**`--format`** **`iso8601`**|**`timestamp`**]::
    The __purpose__ specifies which type of key certificate to determine
    the expiration of.  The only currently recognised __purpose__ is
    "sign". +
     +
    Running **`tor --key-expiration sign`** will attempt to find your
    signing key certificate and will output, both in the logs as well
    as to stdout.  The optional **`--format`** argument lets you specify
    the time format.  Currently, **`iso8601`** and **`timestamp`** are
    supported.  If **`--format`** is not specified, the signing key
    certificate's expiration time will be in ISO-8601 format.  For example,
    the output sent to stdout will be of the form:
    "signing-cert-expiry: 2017-07-25 08:30:15 UTC".  If **`--format`** **`timestamp`**
    is specified, the signing key certificate's expiration time will be in
    Unix timestamp format. For example, the output sent to stdout will be of the form:
    "signing-cert-expiry: 1500971415".

[[opt-dbg]] **--dbg-**...::
    Tor may support other options beginning with the string "dbg". These
    are intended for use by developers to debug and test Tor. They are
    not supported or guaranteed to be stable, and you should probably
    not use them.


[[conf-format]]
== THE CONFIGURATION FILE FORMAT

All configuration options in a configuration are written on a single line by
default.  They take the form of an option name and a value, or an option name
and a quoted value (option value or option "value"). Anything after a #
character is treated as a comment.  Options are
case-insensitive. C-style escaped characters are allowed inside quoted
values. To split one configuration entry into multiple lines, use a single
backslash character (\) before the end of the line.  Comments can be used in
such multiline entries, but they must start at the beginning of a line.

Configuration options can be imported from files or folders using the %include
option with the value being a path. This path can have wildcards. Wildcards are
expanded first, then sorted using lexical order. Then, for each matching file or
folder, the following rules are followed: if the path is a file, the options from
the file will be parsed as if they were written where the %include option is. If
the path is a folder, all files on that folder will be parsed following lexical
order. Files starting with a dot are ignored. Files in subfolders are ignored.
The %include option can be used recursively.
New configuration files or directories cannot be added to already running Tor
instance if **Sandbox** is enabled.

The supported wildcards are * meaning any number of characters including none
and ? meaning exactly one character. These characters can be escaped by preceding
them with a backslash, except on Windows. Files starting with a dot are not matched
when expanding wildcards unless the starting dot is explicitly in the pattern, except
on Windows.

By default, an option on the command line overrides an option found in the
configuration file, and an option in a configuration file overrides one in
the defaults file.

This rule is simple for options that take a single value, but it can become
complicated for options that are allowed to occur more than once: if you
specify four SocksPorts in your configuration file, and one more SocksPort on
the command line, the option on the command line will replace __all__ of the
SocksPorts in the configuration file.  If this isn't what you want, prefix
the option name with a plus sign (+), and it will be appended to the previous
set of options instead.  For example, setting SocksPort 9100 will use only
port 9100, but setting +SocksPort 9100 will use ports 9100 and 9050 (because
this is the default).

Alternatively, you might want to remove every instance of an option in the
configuration file, and not replace it at all: you might want to say on the
command line that you want no SocksPorts at all.  To do that, prefix the
option name with a forward slash (/).  You can use the plus sign (+) and the
forward slash (/) in the configuration file and on the command line.

== GENERAL OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

[[AccelDir]] **AccelDir** __DIR__::
    Specify this option if using dynamic hardware acceleration and the engine
    implementation library resides somewhere other than the OpenSSL default.
    Can not be changed while tor is running.

[[AccelName]] **AccelName** __NAME__::
    When using OpenSSL hardware crypto acceleration attempt to load the dynamic
    engine of this name. This must be used for any dynamic hardware engine.
    Names can be verified with the openssl engine command. Can not be changed
    while tor is running. +
     +
    If the engine name is prefixed with a "!", then Tor will exit if the
    engine cannot be loaded.

[[AlternateBridgeAuthority]] **AlternateBridgeAuthority** [__nickname__] [**flags**] __ipv4address__:__port__ __ fingerprint__::
[[AlternateDirAuthority]] **AlternateDirAuthority** [__nickname__] [**flags**] __ipv4address__:__port__ __fingerprint__::
    These options behave as DirAuthority, but they replace fewer of the
    default directory authorities. Using
    AlternateDirAuthority replaces the default Tor directory authorities, but
    leaves the default bridge authorities in
    place.  Similarly,
    AlternateBridgeAuthority replaces the default bridge authority,
    but leaves the directory authorities alone.

[[AvoidDiskWrites]] **AvoidDiskWrites** **0**|**1**::
    If non-zero, try to write to disk less frequently than we would otherwise.
    This is useful when running on flash memory or other media that support
    only a limited number of writes. (Default: 0)

[[BandwidthBurst]] **BandwidthBurst** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    Limit the maximum token bucket size (also known as the burst) to the given
    number of bytes in each direction. (Default: 1 GByte)

[[BandwidthRate]] **BandwidthRate** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    A token bucket limits the average incoming bandwidth usage on this node
    to the specified number of bytes per second, and the average outgoing
    bandwidth usage to that same value.  If you want to run a relay in the
    public network, this needs to be _at the very least_ 75 KBytes for a
    relay (that is, 600 kbits) or 50 KBytes for a bridge (400 kbits) -- but of
    course, more is better; we recommend at least 250 KBytes (2 mbits) if
    possible.  (Default: 1 GByte) +
     +
    Note that this option, and other bandwidth-limiting options, apply to TCP
    data only: They do not count TCP headers or DNS traffic. +
     +
    Tor uses powers of two, not powers of ten, so 1 GByte is
    1024*1024*1024 bytes as opposed to 1 billion bytes. +
     +
    With this option, and in other options that take arguments in bytes,
    KBytes, and so on, other formats are also supported. Notably, "KBytes" can
    also be written as "kilobytes" or "kb"; "MBytes" can be written as
    "megabytes" or "MB"; "kbits" can be written as "kilobits"; and so forth.
    Case doesn't matter.
    Tor also accepts "byte" and "bit" in the singular.
    The prefixes "tera" and "T" are also recognized.
    If no units are given, we default to bytes.
    To avoid confusion, we recommend writing "bytes" or "bits" explicitly,
    since it's easy to forget that "B" means bytes, not bits.

[[CacheDirectory]] **CacheDirectory** __DIR__::
    Store cached directory data in DIR. Can not be changed while tor is
    running.
    (Default: uses the value of DataDirectory.)

[[CacheDirectoryGroupReadable]] **CacheDirectoryGroupReadable** **0**|**1**|**auto**::
    If this option is set to 0, don't allow the filesystem group to read the
    CacheDirectory. If the option is set to 1, make the CacheDirectory readable
    by the default GID. If the option is "auto", then we use the
    setting for DataDirectoryGroupReadable when the CacheDirectory is the
    same as the DataDirectory, and 0 otherwise. (Default: auto)

[[CircuitPriorityHalflife]] **CircuitPriorityHalflife** __NUM__::
    If this value is set, we override the default algorithm for choosing which
    circuit's cell to deliver or relay next. It is delivered first to the
    circuit that has the lowest weighted cell count, where cells are weighted
    exponentially according to this value (in seconds). If the value is -1, it
    is taken from the consensus if possible else it will fallback to the
    default value of 30. Minimum: 1, Maximum: 2147483647. This can be defined
    as a float value. This is an advanced option; you generally shouldn't have
    to mess with it. (Default: -1)

[[ClientTransportPlugin]] **ClientTransportPlugin** __transport__ socks4|socks5 __IP__:__PORT__::
[[ClientTransportPlugin-2]] **ClientTransportPlugin** __transport__ exec __path-to-binary__ [options]::
    In its first form, when set along with a corresponding Bridge line, the Tor
    client forwards its traffic to a SOCKS-speaking proxy on "IP:PORT".
    (IPv4 addresses should written as-is; IPv6 addresses should be wrapped in
    square brackets.) It's the
    duty of that proxy to properly forward the traffic to the bridge. +
     +
    In its second form, when set along with a corresponding Bridge line, the Tor
    client launches the pluggable transport proxy executable in
    __path-to-binary__ using __options__ as its command-line options, and
    forwards its traffic to it. It's the duty of that proxy to properly forward
    the traffic to the bridge. (Default: none)

[[ConfluxEnabled]] **ConfluxEnabled** **0**|**1**|**auto**::
    If this option is set to 1, general purpose traffic will use Conflux which
    is traffic splitting among multiple legs (circuits). Onion services are not
    supported at the moment. Default value is set to "auto" meaning the
    consensus is used to decide unless set. (Default: auto)

[[ConfluxClientUX]] **ConfluxClientUX** **throughput**|**latency**|**throughput_lowmem**|**latency_lowmem**::
    This option configures the user experience that the client requests from
    the exit, for data that the exit sends to the client. The default is
    "throughput", which maximizes throughput. "Latency" will tell the exit to
    only use the circuit with lower latency for all data. The lowmem versions
    minimize queue usage memory at the client. (Default: "throughput")

[[ConnLimit]] **ConnLimit** __NUM__::
    The minimum number of file descriptors that must be available to the Tor
    process before it will start. Tor will ask the OS for as many file
    descriptors as the OS will allow (you can find this by "ulimit -H -n").
    If this number is less than ConnLimit, then Tor will refuse to start. +
     +
    Tor relays need thousands of sockets, to connect to every other relay.
    If you are running a private bridge, you can reduce the number of sockets
    that Tor uses. For example, to limit Tor to 500 sockets, run
    "ulimit -n 500" in a shell. Then start tor in the same shell, with
    **ConnLimit 500**. You may also need to set **DisableOOSCheck 0**. +
     +
    Unless you have severely limited sockets, you probably don't need to
    adjust **ConnLimit** itself. It has no effect on Windows, since that
    platform lacks getrlimit(). (Default: 1000)

[[ConstrainedSockets]] **ConstrainedSockets** **0**|**1**::
    If set, Tor will tell the kernel to attempt to shrink the buffers for all
    sockets to the size specified in **ConstrainedSockSize**. This is useful for
    virtual servers and other environments where system level TCP buffers may
    be limited. If you're on a virtual server, and you encounter the "Error
    creating network socket: No buffer space available" message, you are
    likely experiencing this problem. +
     +
    The preferred solution is to have the admin increase the buffer pool for
    the host itself via /proc/sys/net/ipv4/tcp_mem or equivalent facility;
    this configuration option is a second-resort. +
     +
    The DirPort option should also not be used if TCP buffers are scarce. The
    cached directory requests consume additional sockets which exacerbates
    the problem. +
     +
    You should **not** enable this feature unless you encounter the "no buffer
    space available" issue. Reducing the TCP buffers affects window size for
    the TCP stream and will reduce throughput in proportion to round trip
    time on long paths. (Default: 0)

[[ConstrainedSockSize]] **ConstrainedSockSize** __N__ **bytes**|**KBytes**::
    When **ConstrainedSockets** is enabled the receive and transmit buffers for
    all sockets will be set to this limit. Must be a value between 2048 and
    262144, in 1024 byte increments. Default of 8192 is recommended.

[[ControlPort]] **ControlPort** ['address'**:**]{empty}__port__|**unix:**__path__|**auto** [__flags__]::
    If set, Tor will accept connections on this port and allow those
    connections to control the Tor process using the Tor Control Protocol
    (described in control-spec.txt in
    https://spec.torproject.org[torspec]). Note: unless you also
    specify one or more of **HashedControlPassword** or
    **CookieAuthentication**, setting this option will cause Tor to allow
    any process on the local host to control it. (Setting both authentication
    methods means either method is sufficient to authenticate to Tor.) This
    option is required for many Tor controllers; most use the value of 9051.
    If a unix domain socket is used, you may quote the path using standard
    C escape sequences. You can specify this directive multiple times, to
    bind to multiple address/port pairs.
    Set it to "auto" to have Tor pick a port for you. (Default: 0) +
     +
    Recognized flags are:
    **GroupWritable**;;
        Unix domain sockets only: makes the socket get created as
        group-writable.
    **WorldWritable**;;
        Unix domain sockets only: makes the socket get created as
        world-writable.
    **RelaxDirModeCheck**;;
        Unix domain sockets only: Do not insist that the directory
        that holds the socket be read-restricted.

[[ControlPortFileGroupReadable]] **ControlPortFileGroupReadable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read the
    control port file. If the option is set to 1, make the control port
    file readable by the default GID. (Default: 0)

[[ControlPortWriteToFile]] **ControlPortWriteToFile** __Path__::
    If set, Tor writes the address and port of any control port it opens to
    this address.  Usable by controllers to learn the actual control port
    when ControlPort is set to "auto".

[[ControlSocket]] **ControlSocket** __Path__::
    Like ControlPort, but listens on a Unix domain socket, rather than a TCP
    socket. '0' disables ControlSocket. (Unix and Unix-like systems only.)
    (Default: 0)

[[ControlSocketsGroupWritable]] **ControlSocketsGroupWritable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read and
    write unix sockets (e.g. ControlSocket). If the option is set to 1, make
    the control socket readable and writable by the default GID. (Default: 0)

[[CookieAuthentication]] **CookieAuthentication** **0**|**1**::
    If this option is set to 1, allow connections on the control port
    when the connecting process knows the contents of a file named
    "control_auth_cookie", which Tor will create in its data directory. This
    authentication method should only be used on systems with good filesystem
    security. (Default: 0)

[[CookieAuthFile]] **CookieAuthFile** __Path__::
    If set, this option overrides the default location and file name
    for Tor's cookie file. (See <<CookieAuthentication,CookieAuthentication>>.)

[[CookieAuthFileGroupReadable]] **CookieAuthFileGroupReadable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read the
    cookie file. If the option is set to 1, make the cookie file readable by
    the default GID. [Making the file readable by other groups is not yet
    implemented; let us know if you need this for some reason.] (Default: 0)

[[CountPrivateBandwidth]] **CountPrivateBandwidth** **0**|**1**::
    If this option is set, then Tor's rate-limiting applies not only to
    remote connections, but also to connections to private addresses like
    127.0.0.1 or 10.0.0.1.  This is mostly useful for debugging
    rate-limiting.  (Default: 0)

[[DataDirectory]] **DataDirectory** __DIR__::
    Store working data in DIR. Can not be changed while tor is running.
    (Default: ~/.tor if your home directory is not /; otherwise,
    @LOCALSTATEDIR@/lib/tor.  On Windows, the default is
    your ApplicationData folder.)

[[DataDirectoryGroupReadable]] **DataDirectoryGroupReadable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read the
    DataDirectory. If the option is set to 1, make the DataDirectory readable
    by the default GID. (Default: 0)

[[DirAuthority]] **DirAuthority** [__nickname__] [**flags**] __ipv4address__:__dirport__ __fingerprint__::
    Use a nonstandard authoritative directory server at the provided address
    and port, with the specified key fingerprint. This option can be repeated
    many times, for multiple authoritative directory servers. Flags are
    separated by spaces, and determine what kind of an authority this directory
    is. By default, an authority is not authoritative for any directory style
    or version unless an appropriate flag is given. +
     +
    Tor will use this authority as a bridge authoritative directory if the
    "bridge" flag is set. If a flag "orport=**orport**" is given, Tor will
    use the given port when opening encrypted tunnels to the dirserver. If a
    flag "weight=**num**" is given, then the directory server is chosen
    randomly with probability proportional to that weight (default 1.0). If a
    flag "v3ident=**fp**" is given, the dirserver is a v3 directory authority
    whose v3 long-term signing key has the fingerprint **fp**. Lastly,
    if an "ipv6=**[**__ipv6address__**]**:__orport__" flag is present, then
    the directory authority is listening for IPv6 connections on the
    indicated IPv6 address and OR Port. +
     +
    Tor will contact the authority at __ipv4address__ to
    download directory documents. Clients always use the ORPort. Relays
    usually use the DirPort, but will use the ORPort in some circumstances.
    If an IPv6 ORPort is supplied, clients will also download directory
    documents at the IPv6 ORPort, if they are configured to use IPv6. +
     +
    If no **DirAuthority** line is given, Tor will use the default directory
    authorities. NOTE: this option is intended for setting up a private Tor
    network with its own directory authorities. If you use it, you will be
    distinguishable from other users, because you won't believe the same
    authorities they do.

[[DirAuthorityFallbackRate]] **DirAuthorityFallbackRate** __NUM__::
    When configured to use both directory authorities and fallback
    directories, the directory authorities also work as fallbacks. They are
    chosen with their regular weights, multiplied by this number, which
    should be 1.0 or less. The default is less than 1, to reduce load on
    authorities. (Default: 0.1)

[[DisableAllSwap]] **DisableAllSwap** **0**|**1**::
    If set to 1, Tor will attempt to lock all current and future memory pages,
    so that memory cannot be paged out. Windows, OS X and Solaris are currently
    not supported. We believe that this feature works on modern Gnu/Linux
    distributions, and that it should work on *BSD systems (untested). This
    option requires that you start your Tor as root, and you should use the
    **User** option to properly reduce Tor's privileges.
    Can not be changed while tor is running. (Default: 0)

[[DisableDebuggerAttachment]] **DisableDebuggerAttachment** **0**|**1**::
   If set to 1, Tor will attempt to prevent basic debugging attachment attempts
   by other processes. This may also keep Tor from generating core files if
   it crashes. It has no impact for users who wish to attach if they
   have CAP_SYS_PTRACE or if they are root.  We believe that this feature
   works on modern Gnu/Linux distributions, and that it may also work on *BSD
   systems (untested).  Some modern Gnu/Linux systems such as Ubuntu have the
   kernel.yama.ptrace_scope sysctl and by default enable it as an attempt to
   limit the PTRACE scope for all user processes by default. This feature will
   attempt to limit the PTRACE scope for Tor specifically - it will not attempt
   to alter the system wide ptrace scope as it may not even exist. If you wish
   to attach to Tor with a debugger such as gdb or strace you will want to set
   this to 0 for the duration of your debugging. Normal users should leave it
   on. Disabling this option while Tor is running is prohibited. (Default: 1)

[[DisableNetwork]] **DisableNetwork** **0**|**1**::
    When this option is set, we don't listen for or accept any connections
    other than controller connections, and we close (and don't reattempt)
    any outbound
    connections.  Controllers sometimes use this option to avoid using
    the network until Tor is fully configured.  Tor will make still certain
    network-related calls (like DNS lookups) as a part of its configuration
    process, even if DisableNetwork is set. (Default: 0)

[[ExtendByEd25519ID]] **ExtendByEd25519ID** **0**|**1**|**auto**::
    If this option is set to 1, we always try to include a relay's Ed25519 ID
    when telling the preceding relay in a circuit to extend to it.
    If this option is set to 0, we never include Ed25519 IDs when extending
    circuits.  If the option is set to "auto", we obey a
    parameter in the consensus document. (Default: auto)

[[ExtORPort]] **ExtORPort** ['address'**:**]{empty}__port__|**auto**::
    Open this port to listen for Extended ORPort connections from your
    pluggable transports. +
    (Default: **DataDirectory**/extended_orport_auth_cookie)

[[ExtORPortCookieAuthFile]] **ExtORPortCookieAuthFile** __Path__::
    If set, this option overrides the default location and file name
    for the Extended ORPort's cookie file -- the cookie file is needed
    for pluggable transports to communicate through the Extended ORPort.

[[ExtORPortCookieAuthFileGroupReadable]] **ExtORPortCookieAuthFileGroupReadable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read the
    Extended OR Port cookie file. If the option is set to 1, make the cookie
    file readable by the default GID. [Making the file readable by other
    groups is not yet implemented; let us know if you need this for some
    reason.] (Default: 0)

[[FallbackDir]] **FallbackDir** __ipv4address__:__dirport__ orport=__orport__ id=__fingerprint__ [weight=__num__] [ipv6=**[**__ipv6address__**]**:__orport__]::
    When tor is unable to connect to any directory cache for directory info
    (usually because it doesn't know about any yet) it tries a hard-coded
    directory. Relays try one directory authority at a time. Clients try
    multiple directory authorities and FallbackDirs, to avoid hangs on
    startup if a hard-coded directory is down. Clients wait for a few seconds
    between each attempt, and retry FallbackDirs more often than directory
    authorities, to reduce the load on the directory authorities.  +
     +
    FallbackDirs should be stable relays with stable IP addresses, ports,
    and identity keys. They must have a DirPort. +
     +
    By default, the directory authorities are also FallbackDirs. Specifying a
    FallbackDir replaces Tor's default hard-coded FallbackDirs (if any).
    (See <<DirAuthority,DirAuthority>> for an explanation of each flag.)

[[FetchDirInfoEarly]] **FetchDirInfoEarly** **0**|**1**::
    If set to 1, Tor will always fetch directory information like other
    directory caches, even if you don't meet the normal criteria for fetching
    early. Normal users should leave it off. (Default: 0)

[[FetchDirInfoExtraEarly]] **FetchDirInfoExtraEarly** **0**|**1**::
    If set to 1, Tor will fetch directory information before other directory
    caches. It will attempt to download directory information closer to the
    start of the consensus period. Normal users should leave it off.
    (Default: 0)

[[FetchHidServDescriptors]] **FetchHidServDescriptors** **0**|**1**::
    If set to 0, Tor will never fetch any hidden service descriptors from the
    rendezvous directories. This option is only useful if you're using a Tor
    controller that handles hidden service fetches for you. (Default: 1)

[[FetchServerDescriptors]] **FetchServerDescriptors** **0**|**1**::
    If set to 0, Tor will never fetch any network status summaries or server
    descriptors from the directory servers. This option is only useful if
    you're using a Tor controller that handles directory fetches for you.
    (Default: 1)

[[FetchUselessDescriptors]] **FetchUselessDescriptors** **0**|**1**::
    If set to 1, Tor will fetch every consensus flavor, and all server
    descriptors and authority certificates referenced by those consensuses,
    except for extra info descriptors. When this option is 1, Tor will also
    keep fetching descriptors, even when idle.
    If set to 0, Tor will avoid fetching useless descriptors: flavors that it
    is not using to build circuits, and authority certificates it does not
    trust. When Tor hasn't built any application circuits, it will go idle,
    and stop fetching descriptors. This option is useful if you're using a
    tor client with an external parser that uses a full consensus.
    This option fetches all documents except extrainfo descriptors,
    **DirCache** fetches and serves all documents except extrainfo
    descriptors, **DownloadExtraInfo*** fetches extrainfo documents, and serves
    them if **DirCache** is on, and **UseMicrodescriptors** changes the
    flavor of consensuses and descriptors that is fetched and used for
    building circuits. (Default: 0)

[[HardwareAccel]] **HardwareAccel** **0**|**1**::
    If non-zero, try to use built-in (static) crypto hardware acceleration when
    available. Can not be changed while tor is running. (Default: 0)

[[HashedControlPassword]] **HashedControlPassword** __hashed_password__::
    Allow connections on the control port if they present
    the password whose one-way hash is __hashed_password__. You
    can compute the hash of a password by running "tor --hash-password
    __password__". You can provide several acceptable passwords by using more
    than one HashedControlPassword line.

[[HTTPProxy]] **HTTPProxy** __host__[:__port__]::
    Tor will make all its directory requests through this host:port (or host:80
    if port is not specified), rather than connecting directly to any directory
    servers. (DEPRECATED: As of 0.3.1.0-alpha you should use HTTPSProxy.)

[[HTTPProxyAuthenticator]] **HTTPProxyAuthenticator** __username:password__::
    If defined, Tor will use this username:password for Basic HTTP proxy
    authentication, as in RFC 2617. This is currently the only form of HTTP
    proxy authentication that Tor supports; feel free to submit a patch if you
    want it to support others. (DEPRECATED: As of 0.3.1.0-alpha you should use
    HTTPSProxyAuthenticator.)

[[HTTPSProxy]] **HTTPSProxy** __host__[:__port__]::
    Tor will make all its OR (SSL) connections through this host:port (or
    host:443 if port is not specified), via HTTP CONNECT rather than connecting
    directly to servers. You may want to set **FascistFirewall** to restrict
    the set of ports you might try to connect to, if your HTTPS proxy only
    allows connecting to certain ports.

[[HTTPSProxyAuthenticator]] **HTTPSProxyAuthenticator** __username:password__::
    If defined, Tor will use this username:password for Basic HTTPS proxy
    authentication, as in RFC 2617. This is currently the only form of HTTPS
    proxy authentication that Tor supports; feel free to submit a patch if you
    want it to support others.

[[KeepalivePeriod]] **KeepalivePeriod** __NUM__::
    To keep firewalls from expiring connections, send a padding keepalive cell
    every NUM seconds on open connections that are in use. (Default: 5 minutes)

[[KeepBindCapabilities]] **KeepBindCapabilities** **0**|**1**|**auto**::
    On Linux, when we are started as root and we switch our identity using
    the **User** option, the **KeepBindCapabilities** option tells us whether to
    try to retain our ability to bind to low ports.  If this value is 1, we
    try to keep the capability; if it is 0 we do not; and if it is **auto**,
    we keep the capability only if we are configured to listen on a low port.
    Can not be changed while tor is running.
    (Default: auto.)

[[Log]] **Log** __minSeverity__[-__maxSeverity__] **stderr**|**stdout**|**syslog**::
    Send all messages between __minSeverity__ and __maxSeverity__ to the standard
    output stream, the standard error stream, or to the system log. (The
    "syslog" value is only supported on Unix.) Recognized severity levels are
    debug, info, notice, warn, and err. We advise using "notice" in most cases,
    since anything more verbose may provide sensitive information to an
    attacker who obtains the logs. If only one severity level is given, all
    messages of that level or higher will be sent to the listed destination. +
     +
    Some low-level logs may be sent from signal handlers, so their destination
    logs must be signal-safe. These low-level logs include backtraces,
    logging function errors, and errors in code called by logging functions.
    Signal-safe logs are always sent to stderr or stdout. They are also sent to
    a limited number of log files that are configured to log messages at error
    severity from the bug or general domains. They are never sent as syslogs,
    control port log events, or to any API-based log
    destinations.

[[Log2]] **Log** __minSeverity__[-__maxSeverity__] **file** __FILENAME__::
    As above, but send log messages to the listed filename. The
    "Log" option may appear more than once in a configuration file.
    Messages are sent to all the logs that match their severity
    level.

[[Log3]] **Log** **[**__domain__,...**]**__minSeverity__[-__maxSeverity__] ... **file** __FILENAME__ +

[[Log4]] **Log** **[**__domain__,...**]**__minSeverity__[-__maxSeverity__] ... **stderr**|**stdout**|**syslog**::
    As above, but select messages by range of log severity __and__ by a
    set of "logging domains".  Each logging domain corresponds to an area of
    functionality inside Tor.  You can specify any number of severity ranges
    for a single log statement, each of them prefixed by a comma-separated
    list of logging domains.  You can prefix a domain with $$~$$ to indicate
    negation, and use * to indicate "all domains".  If you specify a severity
    range without a list of domains, it matches all domains. +
     +
    This is an advanced feature which is most useful for debugging one or two
    of Tor's subsystems at a time. +
     +
    The currently recognized domains are: general, crypto, net, config, fs,
    protocol, mm, http, app, control, circ, rend, bug, dir, dirserv, or, edge,
    acct, hist, handshake, heartbeat, channel, sched, guard, consdiff, dos,
    process, pt, btrack, and mesg.
    Domain names are case-insensitive. +
     +
    For example, "`Log [handshake]debug [~net,~mm]info notice stdout`" sends
    to stdout: all handshake messages of any severity, all info-and-higher
    messages from domains other than networking and memory management, and all
    messages of severity notice or higher.

[[LogMessageDomains]] **LogMessageDomains** **0**|**1**::
    If 1, Tor includes message domains with each log message.  Every log
    message currently has at least one domain; most currently have exactly
    one.  This doesn't affect controller log messages. (Default: 0)

[[LogTimeGranularity]] **LogTimeGranularity** __NUM__::
    Set the resolution of timestamps in Tor's logs to NUM milliseconds.
    NUM must be positive and either a divisor or a multiple of 1 second.
    Note that this option only controls the granularity written by Tor to
    a file or console log.  Tor does not (for example) "batch up" log
    messages to affect times logged by a controller, times attached to
    syslog messages, or the mtime fields on log files.  (Default: 1 second)

[[MaxAdvertisedBandwidth]] **MaxAdvertisedBandwidth** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    If set, we will not advertise more than this amount of bandwidth for our
    BandwidthRate. Server operators who want to reduce the number of clients
    who ask to build circuits through them (since this is proportional to
    advertised bandwidth rate) can thus reduce the CPU demands on their server
    without impacting network performance.

[[MaxUnparseableDescSizeToLog]] **MaxUnparseableDescSizeToLog** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**::
    Unparseable descriptors (e.g. for votes, consensuses, routers) are logged
    in separate files by hash, up to the specified size in total.  Note that
    only files logged during the lifetime of this Tor process count toward the
    total; this is intended to be used to debug problems without opening live
    servers to resource exhaustion attacks. (Default: 10 MBytes)

[[MetricsPort]] **MetricsPort** ['address'**:**]{empty}__port__ [__format__]::
    WARNING: Before enabling this, it is important to understand that exposing
    tor metrics publicly is dangerous to the Tor network users. Please take
    extra precaution and care when opening this port. Set a very strict access
    policy with MetricsPortPolicy and consider using your operating systems
    firewall features for defense in depth.
     +
    We recommend, for the prometheus __format__, that the only address that
    can access this port should be the Prometheus server itself. Remember that
    the connection is unencrypted (HTTP) hence consider using a tool like
    stunnel to secure the link from this port to the server.
     +
    If set, open this port to listen for an HTTP GET request to "/metrics".
    Upon a request, the collected metrics in the the tor instance are
    formatted for the given format and then sent back. If this is set,
    MetricsPortPolicy must be defined else every request will be rejected.
     +
    Supported format is "prometheus" which is also the default if not set. The
    Prometheus data model can be found here:
    https://prometheus.io/docs/concepts/data_model/
     +
    The tor metrics are constantly collected and they solely consists of
    counters. Thus, asking for those metrics is very lightweight on the tor
    process. (Default: None)
     +
    As an example, here only 5.6.7.8 will be allowed to connect:

        MetricsPort 1.2.3.4:9035
        MetricsPortPolicy accept 5.6.7.8

[[MetricsPortPolicy]] **MetricsPortPolicy** __policy__,__policy__,__...__::
    Set an entrance policy for the **MetricsPort**, to limit who can access
    it. The policies have the same form as exit policies below, except that
    port specifiers are ignored. For multiple entries, this line can be used
    multiple times. It is a reject all by default policy.  (Default: None)
     +
    Please, keep in mind here that if the server collecting metrics on the
    MetricsPort is behind a NAT, then everything behind it can access it. This
    is similar for the case of allowing localhost, every users on the server
    will be able to access it. Again, strongly consider using a tool like
    stunnel to secure the link or to strengthen access control.

[[NoExec]] **NoExec** **0**|**1**::
    If this option is set to 1, then Tor will never launch another
    executable, regardless of the settings of ClientTransportPlugin
    or ServerTransportPlugin.  Once this option has been set to 1,
    it cannot be set back to 0 without restarting Tor. (Default: 0)

[[OutboundBindAddress]] **OutboundBindAddress** __IP__::
    Make all outbound connections originate from the IP address specified. This
    is only useful when you have multiple network interfaces, and you want all
    of Tor's outgoing connections to use a single one. This option may
    be used twice, once with an IPv4 address and once with an IPv6 address.
    IPv6 addresses should be wrapped in square brackets.
    This setting will be ignored for connections to the loopback addresses
    (127.0.0.0/8 and ::1), and is not used for DNS requests as well.

[[OutboundBindAddressExit]] **OutboundBindAddressExit** __IP__::
    Make all outbound exit connections originate from the IP address
    specified. This option overrides **OutboundBindAddress** for the
    same IP version. This option may be used twice, once with an IPv4
    address and once with an IPv6 address.
    IPv6 addresses should be wrapped in square brackets.
    This setting will be ignored
    for connections to the loopback addresses (127.0.0.0/8 and ::1).

[[OutboundBindAddressOR]] **OutboundBindAddressOR** __IP__::
    Make all outbound non-exit (relay and other) connections
    originate from the IP address specified. This option overrides
    **OutboundBindAddress** for the same IP version. This option may
    be used twice, once with an IPv4 address and once with an IPv6
    address. IPv6 addresses should be wrapped in square brackets.
    This setting will be ignored for connections to the loopback
    addresses (127.0.0.0/8 and ::1).

[[OwningControllerProcess]] **{dbl_}OwningControllerProcess** __PID__::
    Make Tor instance periodically check for presence of a controller process
    with given PID and terminate itself if this process is no longer alive.
    Polling interval is 15 seconds.

[[PerConnBWBurst]] **PerConnBWBurst** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    If this option is set manually, or via the "perconnbwburst" consensus
    field, Tor will use it for separate rate limiting for each connection
    from a non-relay. (Default: 0)

[[PerConnBWRate]] **PerConnBWRate** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    If this option is set manually, or via the "perconnbwrate" consensus
    field, Tor will use it for separate rate limiting for each connection
    from a non-relay. (Default: 0)

[[OutboundBindAddressPT]] **OutboundBindAddressPT** __IP__::
    Request that pluggable transports makes all outbound connections
    originate from the IP address specified. Because outgoing connections
    are handled by the pluggable transport itself, it is not possible for
    Tor to enforce whether the pluggable transport honors this option. This
    option overrides **OutboundBindAddress** for the same IP version. This
    option may be used twice, once with an IPv4 address and once with an
    IPv6 address. IPv6 addresses should be wrapped in square brackets. This
    setting will be ignored for connections to the loopback addresses
    (127.0.0.0/8 and ::1).

[[PidFile]] **PidFile** __FILE__::
    On startup, write our PID to FILE. On clean shutdown, remove
    FILE. Can not be changed while tor is running.

[[ProtocolWarnings]] **ProtocolWarnings** **0**|**1**::
    If 1, Tor will log with severity \'warn' various cases of other parties not
    following the Tor specification. Otherwise, they are logged with severity
    \'info'. (Default: 0)

[[RelayBandwidthBurst]] **RelayBandwidthBurst** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    If not 0, limit the maximum token bucket size (also known as the burst) for
    \_relayed traffic_ to the given number of bytes in each direction.
    They do not include directory fetches by the relay (from authority
    or other relays), because that is considered "client" activity. (Default: 0)
    RelayBandwidthBurst defaults to the value of RelayBandwidthRate if unset.

[[RelayBandwidthRate]] **RelayBandwidthRate** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    If not 0, a separate token bucket limits the average incoming bandwidth
    usage for \_relayed traffic_ on this node to the specified number of bytes
    per second, and the average outgoing bandwidth usage to that same value.
    Relayed traffic currently is calculated to include answers to directory
    requests, but that may change in future versions. They do not include directory
    fetches by the relay (from authority or other relays), because that is considered
    "client" activity.  (Default: 0)
    RelayBandwidthRate defaults to the value of RelayBandwidthBurst if unset.

[[RephistTrackTime]] **RephistTrackTime** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    Tells an authority, or other node tracking node reliability and history,
    that fine-grained information about nodes can be discarded when it hasn't
    changed for a given amount of time.  (Default: 24 hours)

[[RunAsDaemon]] **RunAsDaemon** **0**|**1**::
    If 1, Tor forks and daemonizes to the background. This option has no effect
    on Windows; instead you should use the --service command-line option.
    Can not be changed while tor is running.
    (Default: 0)

[[SafeLogging]] **SafeLogging** **0**|**1**|**relay**::
    Tor can scrub potentially sensitive strings from log messages (e.g.
    addresses) by replacing them with the string [scrubbed]. This way logs can
    still be useful, but they don't leave behind personally identifying
    information about what sites a user might have visited. +
     +
    If this option is set to 0, Tor will not perform any scrubbing, if it is
    set to 1, all potentially sensitive strings are replaced. If it is set to
    relay, all log messages generated when acting as a relay are sanitized, but
    all messages generated when acting as a client are not.
    Note: Tor may not heed this option when logging at log levels below Notice.
    (Default: 1)

[[Sandbox]] **Sandbox** **0**|**1**::
    If set to 1, Tor will run securely through the use of a syscall sandbox.
    Otherwise the sandbox will be disabled. The option only works on
    Linux-based operating systems, and only when Tor has been built with the
    libseccomp library.  Note that this option may be incompatible with some
    versions of libc, and some kernel versions.  This option can not be
    changed while tor is running. +
     +
    When the **Sandbox** is 1, the following options can not be changed when tor
    is running:
    **Address**,
    **ConnLimit**,
    **CookieAuthFile**,
    **DirPortFrontPage**,
    **ExtORPortCookieAuthFile**,
    **Logs**,
    **ServerDNSResolvConfFile**,
    **ClientOnionAuthDir** (and any files in it won't reload on HUP signal). +
     +
    Launching new Onion Services through the control port is not supported
    with current syscall sandboxing implementation. +
     +
    Tor must remain in client or server mode (some changes to **ClientOnly**
    and **ORPort** are not allowed). Currently, if **Sandbox** is 1,
    **ControlPort** command "GETINFO address" will not work. +
     +
    When using %include in the tor configuration files, reloading the tor
    configuration is not supported after adding new configuration files or
    directories. +
     +
    (Default: 0)

[[Schedulers]] **Schedulers** **KIST**|**KISTLite**|**Vanilla**::
    Specify the scheduler type that tor should use. The scheduler is
    responsible for moving data around within a Tor process. This is an ordered
    list by priority which means that the first value will be tried first and if
    unavailable, the second one is tried and so on. It is possible to change
    these values at runtime. This option mostly effects relays, and most
    operators should leave it set to its default value.
    (Default: KIST,KISTLite,Vanilla) +
     +
    The possible scheduler types are:
     +
    **KIST**: Kernel-Informed Socket Transport. Tor will use TCP information
    from the kernel to make informed decisions regarding how much data to send
    and when to send it. KIST also handles traffic in batches (see
    <<KISTSchedRunInterval,KISTSchedRunInterval>>) in order to improve traffic prioritization decisions.
    As implemented, KIST will only work on Linux kernel version 2.6.39 or
    higher. +
     +
    **KISTLite**: Same as KIST but without kernel support. Tor will use all
    the same mechanics as with KIST, including the batching, but its decisions
    regarding how much data to send will not be as good. KISTLite will work on
    all kernels and operating systems, and the majority of the benefits of KIST
    are still realized with KISTLite. +
     +
    **Vanilla**: The scheduler that Tor used before KIST was implemented. It
    sends as much data as possible, as soon as possible. Vanilla will work on
    all kernels and operating systems.

// Out of order because it logically belongs near the Schedulers option
[[KISTSchedRunInterval]] **KISTSchedRunInterval** __NUM__ **msec**::
    If KIST or KISTLite is used in the Schedulers option, this controls at which
    interval the scheduler tick is. If the value is 0 msec, the value is taken
    from the consensus if possible else it will fallback to the default 10
    msec. Maximum possible value is 100 msec. (Default: 0 msec)

// Out of order because it logically belongs near the Schedulers option
[[KISTSockBufSizeFactor]] **KISTSockBufSizeFactor** __NUM__::
    If KIST is used in Schedulers, this is a multiplier of the per-socket
    limit calculation of the KIST algorithm. (Default: 1.0)

[[Socks4Proxy]] **Socks4Proxy** __host__[:__port__]::
    Tor will make all OR connections through the SOCKS 4 proxy at host:port
    (or host:1080 if port is not specified).

[[Socks5Proxy]] **Socks5Proxy** __host__[:__port__]::
    Tor will make all OR connections through the SOCKS 5 proxy at host:port
    (or host:1080 if port is not specified).

// Out of order because Username logically precedes Password
[[Socks5ProxyUsername]] **Socks5ProxyUsername** __username__ +

[[Socks5ProxyPassword]] **Socks5ProxyPassword** __password__::
    If defined, authenticate to the SOCKS 5 server using username and password
    in accordance to RFC 1929. Both username and password must be between 1 and
    255 characters.

[[SyslogIdentityTag]] **SyslogIdentityTag** __tag__::
    When logging to syslog, adds a tag to the syslog identity such that
    log entries are marked with "Tor-__tag__". Can not be changed while tor is
    running. (Default: none)

[[TCPProxy]] **TCPProxy** __protocol__ __host__:__port__::
    Tor will use the given protocol to make all its OR (SSL) connections through
    a TCP proxy on host:port, rather than connecting directly to servers. You may
    want to set **FascistFirewall** to restrict the set of ports you might try to
    connect to, if your proxy only allows connecting to certain ports. There is no
    equivalent option for directory connections, because all Tor client versions
    that support this option download directory documents via OR connections. +
+
    The only protocol supported right now is 'haproxy'. This option is only for
    clients. (Default: none) +
+
    The HAProxy version 1 proxy protocol is described in detail at
    https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt +
+
    Both source IP address and source port will be set to zero.

[[TruncateLogFile]] **TruncateLogFile** **0**|**1**::
    If 1, Tor will overwrite logs at startup and in response to a HUP signal,
    instead of appending to them. (Default: 0)

[[UnixSocksGroupWritable]] **UnixSocksGroupWritable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read and
    write unix sockets (e.g. SocksPort unix:). If the option is set to 1, make
    the Unix socket readable and writable by the default GID. (Default: 0)

[[UseDefaultFallbackDirs]] **UseDefaultFallbackDirs** **0**|**1**::
    Use Tor's default hard-coded FallbackDirs (if any). (When a
    FallbackDir line is present, it replaces the hard-coded FallbackDirs,
    regardless of the value of UseDefaultFallbackDirs.) (Default: 1)

[[User]] **User** __Username__::
    On startup, setuid to this user and setgid to their primary group.
    Can not be changed while tor is running.

== CLIENT OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

The following options are useful only for clients (that is, if
**SocksPort**, **HTTPTunnelPort**, **TransPort**, **DNSPort**, or
**NATDPort** is non-zero):

[[AllowNonRFC953Hostnames]] **AllowNonRFC953Hostnames** **0**|**1**::
    When this option is disabled, Tor blocks hostnames containing illegal
    characters (like @ and :) rather than sending them to an exit node to be
    resolved. This helps trap accidental attempts to resolve URLs and so on.
    (Default: 0)

[[AutomapHostsOnResolve]] **AutomapHostsOnResolve** **0**|**1**::
    When this option is enabled, and we get a request to resolve an address
    that ends with one of the suffixes in **AutomapHostsSuffixes**, we map an
    unused virtual address to that address, and return the new virtual address.
    This is handy for making ".onion" addresses work with applications that
    resolve an address and then connect to it. (Default: 0)

[[AutomapHostsSuffixes]] **AutomapHostsSuffixes** __SUFFIX__,__SUFFIX__,__...__::
    A comma-separated list of suffixes to use with **AutomapHostsOnResolve**.
    The "." suffix is equivalent to "all addresses." (Default: .exit,.onion).

[[Bridge]] **Bridge** [__transport__] __IP__:__ORPort__ [__fingerprint__]::
    When set along with UseBridges, instructs Tor to use the relay at
    "IP:ORPort" as a "bridge" relaying into the Tor network. If "fingerprint"
    is provided (using the same format as for DirAuthority), we will verify that
    the relay running at that location has the right fingerprint. We also use
    fingerprint to look up the bridge descriptor at the bridge authority, if
    it's provided and if UpdateBridgesFromAuthority is set too.  +
     +
    If "transport" is provided, it must match a ClientTransportPlugin line. We
    then use that pluggable transport's proxy to transfer data to the bridge,
    rather than connecting to the bridge directly. Some transports use a
    transport-specific method to work out the remote address to connect to.
    These transports typically ignore the "IP:ORPort" specified in the bridge
    line.  +
     +
    Tor passes any "key=val" settings to the pluggable transport proxy as
    per-connection arguments when connecting to the bridge.  Consult
    the documentation of the pluggable transport for details of what
    arguments it supports.

[[CircuitPadding]] **CircuitPadding** **0**|**1**::
    If set to 0, Tor will not pad client circuits with additional cover
    traffic. Only clients may set this option. This option should be offered
    via the UI to mobile users for use where bandwidth may be expensive. If
    set to 1, padding will be negotiated as per the consensus and relay
    support (unlike ConnectionPadding, CircuitPadding cannot be force-enabled).
    (Default: 1)

// Out of order because it logically belongs after CircuitPadding
[[ReducedCircuitPadding]] **ReducedCircuitPadding** **0**|**1**::
    If set to 1, Tor will only use circuit padding algorithms that have low
    overhead. Only clients may set this option. This option should be offered
    via the UI to mobile users for use where bandwidth may be expensive.
    (Default: 0)

[[ClientBootstrapConsensusAuthorityDownloadInitialDelay]] **ClientBootstrapConsensusAuthorityDownloadInitialDelay** __N__::
    Initial delay in seconds for when clients should download consensuses from authorities
    if they are bootstrapping (that is, they don't have a usable, reasonably
    live consensus). Only used by clients fetching from a list of fallback
    directory mirrors. This schedule is advanced by (potentially concurrent)
    connection attempts, unlike other schedules, which are advanced by
    connection failures. (Default: 6)

[[ClientBootstrapConsensusAuthorityOnlyDownloadInitialDelay]] **ClientBootstrapConsensusAuthorityOnlyDownloadInitialDelay** __N__::
    Initial delay in seconds for when clients should download consensuses from authorities
    if they are bootstrapping (that is, they don't have a usable, reasonably
    live consensus). Only used by clients which don't have or won't fetch
    from a list of fallback directory mirrors. This schedule is advanced by
    (potentially concurrent) connection attempts, unlike other schedules,
    which are advanced by connection failures. (Default: 0)

[[ClientBootstrapConsensusFallbackDownloadInitialDelay]] **ClientBootstrapConsensusFallbackDownloadInitialDelay** __N__::
    Initial delay in seconds for when clients should download consensuses from fallback
    directory mirrors if they are bootstrapping (that is, they don't have a
    usable, reasonably live consensus). Only used by clients fetching from a
    list of fallback directory mirrors. This schedule is advanced by
    (potentially concurrent) connection attempts, unlike other schedules,
    which are advanced by connection failures. (Default: 0)

[[ClientBootstrapConsensusMaxInProgressTries]] **ClientBootstrapConsensusMaxInProgressTries** __NUM__::
    Try this many simultaneous connections to download a consensus before
    waiting for one to complete, timeout, or error out. (Default: 3)

[[ClientDNSRejectInternalAddresses]] **ClientDNSRejectInternalAddresses** **0**|**1**::
    If true, Tor does not believe any anonymously retrieved DNS answer that
    tells it that an address resolves to an internal address (like 127.0.0.1 or
    192.168.0.1). This option prevents certain browser-based attacks; it
    is not allowed to be set on the default network. (Default: 1)

[[ClientOnionAuthDir]] **ClientOnionAuthDir** __path__::
    Path to the directory containing v3 hidden service authorization files.
    Each file is for a single onion address, and the files MUST have the suffix
    ".auth_private" (i.e. "bob_onion.auth_private"). The content format MUST be:
     +
      <onion-address>:descriptor:x25519:<base32-encoded-privkey>
     +
    The <onion-address> MUST NOT have the ".onion" suffix. The
    <base32-encoded-privkey> is the base32 representation of the raw key bytes
    only (32 bytes for x25519). See Appendix G in the rend-spec-v3.txt file of
    https://spec.torproject.org/[torspec] for more information.

[[ClientOnly]] **ClientOnly** **0**|**1**::
    If set to 1, Tor will not run as a relay or serve
    directory requests, even if the ORPort, ExtORPort, or DirPort options are
    set. (This config option is
    mostly unnecessary: we added it back when we were considering having
    Tor clients auto-promote themselves to being relays if they were stable
    and fast enough. The current behavior is simply that Tor is a client
    unless ORPort, ExtORPort, or DirPort are configured.) (Default: 0)

[[ClientPreferIPv6DirPort]] **ClientPreferIPv6DirPort** **0**|**1**|**auto**::
    If this option is set to 1, Tor prefers a directory port with an IPv6
    address over one with IPv4, for direct connections, if a given directory
    server has both. (Tor also prefers an IPv6 DirPort if IPv4Client is set to
    0.) If this option is set to auto, clients prefer IPv4. Other things may
    influence the choice. This option breaks a tie to the favor of IPv6.
    (Default: auto)  (DEPRECATED: This option has had no effect for some
    time.)

[[ClientPreferIPv6ORPort]] **ClientPreferIPv6ORPort** **0**|**1**|**auto**::
    If this option is set to 1, Tor prefers an OR port with an IPv6
    address over one with IPv4 if a given entry node has both. (Tor also
    prefers an IPv6 ORPort if IPv4Client is set to 0.) If this option is set
    to auto, Tor bridge clients prefer the configured bridge address, and
    other clients prefer IPv4. Other things may influence the choice. This
    option breaks a tie to the favor of IPv6. (Default: auto)

[[ClientRejectInternalAddresses]] **ClientRejectInternalAddresses** **0**|**1**::
    If true, Tor does not try to fulfill requests to connect to an internal
    address (like 127.0.0.1 or 192.168.0.1) __unless an exit node is
    specifically requested__ (for example, via a .exit hostname, or a
    controller request).  If true, multicast DNS hostnames for machines on the
    local network (of the form *.local) are also rejected.  (Default: 1)

[[ClientUseIPv4]] **ClientUseIPv4** **0**|**1**::
    If this option is set to 0, Tor will avoid connecting to directory servers
    and entry nodes over IPv4. Note that clients with an IPv4
    address in a **Bridge**, proxy, or pluggable transport line will try
    connecting over IPv4 even if **ClientUseIPv4** is set to 0. (Default: 1)

[[ClientUseIPv6]] **ClientUseIPv6** **0**|**1**::
    If this option is set to 1, Tor might connect to directory servers or
    entry nodes over IPv6. For IPv6 only hosts, you need to also set
    **ClientUseIPv4** to 0 to disable IPv4. Note that clients configured with
    an IPv6 address in a **Bridge**, proxy, or pluggable transportline will
    try connecting over IPv6 even if **ClientUseIPv6** is set to 0. (Default: 1)

[[ConnectionPadding]] **ConnectionPadding** **0**|**1**|**auto**::
    This option governs Tor's use of padding to defend against some forms of
    traffic analysis. If it is set to 'auto', Tor will send padding only
    if both the client and the relay support it. If it is set to 0, Tor will
    not send any padding cells. If it is set to 1, Tor will still send padding
    for client connections regardless of relay support. Only clients may set
    this option. This option should be offered via the UI to mobile users
    for use where bandwidth may be expensive.
    (Default: auto)

// Out of order because it logically belongs after ConnectionPadding
[[ReducedConnectionPadding]] **ReducedConnectionPadding** **0**|**1**::
    If set to 1, Tor will not not hold OR connections open for very long,
    and will send less padding on these connections. Only clients may set
    this option. This option should be offered via the UI to mobile users
    for use where bandwidth may be expensive. (Default: 0)

[[DNSPort]] **DNSPort** ['address'**:**]{empty}__port__|**auto** [_isolation flags_]::
    If non-zero, open this port to listen for UDP DNS requests, and resolve
    them anonymously.  This port only handles A, AAAA, and PTR requests---it
    doesn't handle arbitrary DNS request types. Set the port to "auto" to
    have Tor pick a port for
    you. This directive can be specified multiple times to bind to multiple
    addresses/ports. See <<SocksPort,SocksPort>> for an explanation of isolation
    flags. (Default: 0)

[[DownloadExtraInfo]] **DownloadExtraInfo** **0**|**1**::
    If true, Tor downloads and caches "extra-info" documents. These documents
    contain information about servers other than the information in their
    regular server descriptors. Tor does not use this information for anything
    itself; to save bandwidth, leave this option turned off. (Default: 0)

[[EnforceDistinctSubnets]] **EnforceDistinctSubnets** **0**|**1**::
    If 1, Tor will not put two servers whose IP addresses are "too close" on
    the same circuit. Currently, two addresses are "too close" if they lie in
    the same /16 range. (Default: 1)

[[FascistFirewall]] **FascistFirewall** **0**|**1**::
    If 1, Tor will only create outgoing connections to ORs running on ports
    that your firewall allows (defaults to 80 and 443; see <<FirewallPorts,FirewallPorts>>).
    This will allow you to run Tor as a client behind a firewall with
    restrictive policies, but will not allow you to run as a server behind such
    a firewall. If you prefer more fine-grained control, use
    ReachableAddresses instead.

[[FirewallPorts]] **FirewallPorts** __PORTS__::
    A list of ports that your firewall allows you to connect to. Only used when
    **FascistFirewall** is set. This option is deprecated; use ReachableAddresses
    instead. (Default: 80, 443)

[[HTTPTunnelPort]] **HTTPTunnelPort** ['address'**:**]{empty}__port__|**auto** [_isolation flags_]::
    Open this port to listen for proxy connections using the "HTTP CONNECT"
    protocol instead of SOCKS. Set this to
    0 if you don't want to allow "HTTP CONNECT" connections. Set the port
    to "auto" to have Tor pick a port for you. This directive can be
    specified multiple times to bind to multiple addresses/ports. If multiple
    entries of this option are present in your configuration file, Tor will
    perform stream isolation between listeners by default. See
    <<SocksPort,SocksPort>> for an explanation of isolation flags. (Default: 0)

[[LongLivedPorts]] **LongLivedPorts** __PORTS__::
    A list of ports for services that tend to have long-running connections
    (e.g. chat and interactive shells). Circuits for streams that use these
    ports will contain only high-uptime nodes, to reduce the chance that a node
    will go down before the stream is finished. Note that the list is also
    honored for circuits (both client and service side) involving hidden
    services whose virtual port is in this list. (Default: 21, 22, 706,
    1863, 5050, 5190, 5222, 5223, 6523, 6667, 6697, 8300)

[[MapAddress]] **MapAddress** __address__ __newaddress__::
    When a request for address arrives to Tor, it will transform to newaddress
    before processing it. For example, if you always want connections to
    www.example.com to exit via __torserver__ (where __torserver__ is the
    fingerprint of the server), use "MapAddress www.example.com
    www.example.com.torserver.exit". If the value is prefixed with a
    "\*.", matches an entire domain. For example, if you
    always want connections to example.com and any if its subdomains
    to exit via
    __torserver__ (where __torserver__ is the fingerprint of the server), use
    "MapAddress \*.example.com \*.example.com.torserver.exit". (Note the
    leading "*." in each part of the directive.) You can also redirect all
    subdomains of a domain to a single address. For example, "MapAddress
    *.example.com www.example.com". If the specified exit is not available,
    or the exit can not connect to the site, Tor will fail any connections
    to the mapped address.+
     +
    NOTES:

    1. When evaluating MapAddress expressions Tor stops when it hits the most
    recently added expression that matches the requested address. So if you
    have the following in your torrc, www.torproject.org will map to
    198.51.100.1:

     MapAddress www.torproject.org 192.0.2.1
     MapAddress www.torproject.org 198.51.100.1

    2. Tor evaluates the MapAddress configuration until it finds no matches. So
    if you have the following in your torrc, www.torproject.org will map to
    203.0.113.1:

      MapAddress 198.51.100.1 203.0.113.1
      MapAddress www.torproject.org 198.51.100.1

    3. The following MapAddress expression is invalid (and will be
    ignored) because you cannot map from a specific address to a wildcard
    address:

      MapAddress www.torproject.org *.torproject.org.torserver.exit

    4. Using a wildcard to match only part of a string (as in *ample.com) is
    also invalid.

    5. Tor maps hostnames and IP addresses separately. If you MapAddress
       a DNS name, but use an IP address to connect, then Tor will ignore the
       DNS name mapping.

    6. MapAddress does not apply to redirects in the application protocol.
       For example, HTTP redirects and alt-svc headers will ignore mappings
       for the original address. You can use a wildcard mapping to handle
       redirects within the same site.

[[MaxCircuitDirtiness]] **MaxCircuitDirtiness** __NUM__::
    Feel free to reuse a circuit that was first used at most NUM seconds ago,
    but never attach a new stream to a circuit that is too old.  For hidden
    services, this applies to the __last__ time a circuit was used, not the
    first. Circuits with streams constructed with SOCKS authentication via
    SocksPorts that have **KeepAliveIsolateSOCKSAuth** also remain alive
    for MaxCircuitDirtiness seconds after carrying the last such stream.
    (Default: 10 minutes)

[[MaxClientCircuitsPending]] **MaxClientCircuitsPending** __NUM__::
    Do not allow more than NUM circuits to be pending at a time for handling
    client streams. A circuit is pending if we have begun constructing it,
    but it has not yet been completely constructed.  (Default: 32)

[[NATDPort]] **NATDPort** ['address'**:**]{empty}__port__|**auto** [_isolation flags_]::
    Open this port to listen for connections from old versions of ipfw (as
    included in old versions of FreeBSD, etc) using the NATD protocol.
    Use 0 if you don't want to allow NATD connections.  Set the port
    to "auto" to have Tor pick a port for you. This directive can be
    specified multiple times to bind to multiple addresses/ports.  If multiple
    entries of this option are present in your configuration file, Tor will
    perform stream isolation between listeners by default. See
    <<SocksPort,SocksPort>> for an explanation of isolation flags. +
     +
    This option is only for people who cannot use TransPort. (Default: 0)

[[NewCircuitPeriod]] **NewCircuitPeriod** __NUM__::
    Every NUM seconds consider whether to build a new circuit. (Default: 30
    seconds)

// These are out of order because they logically belong together
[[PathBiasCircThreshold]] **PathBiasCircThreshold** __NUM__ +

[[PathBiasDropGuards]] **PathBiasDropGuards** __NUM__ +

[[PathBiasExtremeRate]] **PathBiasExtremeRate** __NUM__ +

[[PathBiasNoticeRate]] **PathBiasNoticeRate** __NUM__ +

[[PathBiasWarnRate]] **PathBiasWarnRate** __NUM__ +

[[PathBiasScaleThreshold]] **PathBiasScaleThreshold** __NUM__::
    These options override the default behavior of Tor's (**currently
    experimental**) path bias detection algorithm. To try to find broken or
    misbehaving guard nodes, Tor looks for nodes where more than a certain
    fraction of circuits through that guard fail to get built. +
     +
    The PathBiasCircThreshold option controls how many circuits we need to build
    through a guard before we make these checks.  The PathBiasNoticeRate,
    PathBiasWarnRate and PathBiasExtremeRate options control what fraction of
    circuits must succeed through a guard so we won't write log messages.
    If less than PathBiasExtremeRate circuits succeed *and* PathBiasDropGuards
    is set to 1, we disable use of that guard. +
     +
    When we have seen more than PathBiasScaleThreshold
    circuits through a guard, we scale our observations by 0.5 (governed by
    the consensus) so that new observations don't get swamped by old ones. +
     +
    By default, or if a negative value is provided for one of these options,
    Tor uses reasonable defaults from the networkstatus consensus document.
    If no defaults are available there, these options default to 150, .70,
    .50, .30, 0, and 300 respectively.

// These are out of order because they logically belong together
[[PathBiasUseThreshold]] **PathBiasUseThreshold** __NUM__ +

[[PathBiasNoticeUseRate]] **PathBiasNoticeUseRate** __NUM__ +

[[PathBiasExtremeUseRate]] **PathBiasExtremeUseRate** __NUM__ +

[[PathBiasScaleUseThreshold]] **PathBiasScaleUseThreshold** __NUM__::
    Similar to the above options, these options override the default behavior
    of Tor's (**currently experimental**) path use bias detection algorithm. +
     +
    Where as the path bias parameters govern thresholds for successfully
    building circuits, these four path use bias parameters govern thresholds
    only for circuit usage. Circuits which receive no stream usage
    are not counted by this detection algorithm. A used circuit is considered
    successful if it is capable of carrying streams or otherwise receiving
    well-formed responses to RELAY cells. +
     +
    By default, or if a negative value is provided for one of these options,
    Tor uses reasonable defaults from the networkstatus consensus document.
    If no defaults are available there, these options default to 20, .80,
    .60, and 100, respectively.

[[PathsNeededToBuildCircuits]] **PathsNeededToBuildCircuits** __NUM__::
    Tor clients don't build circuits for user traffic until they know
    about enough of the network so that they could potentially construct
    enough of the possible paths through the network. If this option
    is set to a fraction between 0.25 and 0.95, Tor won't build circuits
    until it has enough descriptors or microdescriptors to construct
    that fraction of possible paths. Note that setting this option too low
    can make your Tor client less anonymous, and setting it too high can
    prevent your Tor client from bootstrapping.  If this option is negative,
    Tor will use a default value chosen by the directory authorities. If the
    directory authorities do not choose a value, Tor will default to 0.6.
    (Default: -1)

[[ReachableAddresses]] **ReachableAddresses** __IP__[/__MASK__][:__PORT__]...::
    A comma-separated list of IP addresses and ports that your firewall allows
    you to connect to. The format is as for the addresses in ExitPolicy, except
    that "accept" is understood unless "reject" is explicitly provided. For
    example, \'ReachableAddresses 99.0.0.0/8, reject 18.0.0.0/8:80, accept
    \*:80' means that your firewall allows connections to everything inside net
    99, rejects port 80 connections to net 18, and accepts connections to port
    80 otherwise. (Default: \'accept \*:*'.)

[[ReachableDirAddresses]] **ReachableDirAddresses** __IP__[/__MASK__][:__PORT__]...::
    Like **ReachableAddresses**, a list of addresses and ports. Tor will obey
    these restrictions when fetching directory information, using standard HTTP
    GET requests. If not set explicitly then the value of
    **ReachableAddresses** is used. If **HTTPProxy** is set then these
    connections will go through that proxy.   (DEPRECATED: This option has
    had no effect for some time.)

[[ReachableORAddresses]] **ReachableORAddresses** __IP__[/__MASK__][:__PORT__]...::
    Like **ReachableAddresses**, a list of addresses and ports. Tor will obey
    these restrictions when connecting to Onion Routers, using TLS/SSL. If not
    set explicitly then the value of **ReachableAddresses** is used. If
    **HTTPSProxy** is set then these connections will go through that proxy. +
     +
    The separation between **ReachableORAddresses** and
    **ReachableDirAddresses** is only interesting when you are connecting
    through proxies (see <<HTTPProxy,HTTPProxy>> and <<HTTPSProxy,HTTPSProxy>>). Most proxies limit
    TLS connections (which Tor uses to connect to Onion Routers) to port 443,
    and some limit HTTP GET requests (which Tor uses for fetching directory
    information) to port 80.

[[SafeSocks]] **SafeSocks** **0**|**1**::
    When this option is enabled, Tor will reject application connections that
    use unsafe variants of the socks protocol -- ones that only provide an IP
    address, meaning the application is doing a DNS resolve first.
    Specifically, these are socks4 and socks5 when not doing remote DNS.
    (Default: 0)

// Out of order because it logically belongs after SafeSocks
[[TestSocks]] **TestSocks** **0**|**1**::
    When this option is enabled, Tor will make a notice-level log entry for
    each connection to the Socks port indicating whether the request used a
    safe socks protocol or an unsafe one (see <<SafeSocks,SafeSocks>>). This
    helps to determine whether an application using Tor is possibly leaking
    DNS requests. (Default: 0)

// Out of order because it logically belongs with SafeSocks
[[WarnPlaintextPorts]] **WarnPlaintextPorts** __port__,__port__,__...__::
    Tells Tor to issue a warnings whenever the user tries to make an anonymous
    connection to one of these ports. This option is designed to alert users
    to services that risk sending passwords in the clear. (Default:
    23,109,110,143)

// Out of order because it logically belongs with SafeSocks
[[RejectPlaintextPorts]] **RejectPlaintextPorts** __port__,__port__,__...__::
    Like WarnPlaintextPorts, but instead of warning about risky port uses, Tor
    will instead refuse to make the connection. (Default: None)

[[SocksPolicy]] **SocksPolicy** __policy__,__policy__,__...__::
    Set an entrance policy for this server, to limit who can connect to the
    SocksPort and DNSPort ports. The policies have the same form as exit
    policies below, except that port specifiers are ignored. Any address
    not matched by some entry in the policy is accepted.

[[SocksPort]] **SocksPort** ['address'**:**]{empty}__port__|**unix:**__path__|**auto** [_flags_] [_isolation flags_]::
    Open this port to listen for connections from SOCKS-speaking
    applications. Set this to 0 if you don't want to allow application
    connections via SOCKS. Set it to "auto" to have Tor pick a port for
    you. This directive can be specified multiple times to bind
    to multiple addresses/ports. If a unix domain socket is used, you may
    quote the path using standard C escape sequences. Most flags are off by
    default, except where specified. Flags that are on by default can be
    disabled by putting "No" before the flag name.
    (Default: 9050) +
     +
        NOTE: Although this option allows you to specify an IP address
        other than localhost, you should do so only with extreme caution.
        The SOCKS protocol is unencrypted and (as we use it)
        unauthenticated, so exposing it in this way could leak your
        information to anybody watching your network, and allow anybody
        to use your computer as an open proxy. +
     +
    If multiple entries of this option are present in your configuration
    file, Tor will perform stream isolation between listeners by default.
    The _isolation flags_ arguments give Tor rules for which streams
    received on this SocksPort are allowed to share circuits with one
    another.  Recognized isolation flags are:
    **IsolateClientAddr**;;
        Don't share circuits with streams from a different
        client address.  (On by default and strongly recommended when
        supported; you can disable it with **NoIsolateClientAddr**.
        Unsupported and force-disabled when using Unix domain sockets.)
    **IsolateSOCKSAuth**;;
        Don't share circuits with streams for which different
        SOCKS authentication was provided. (For HTTPTunnelPort
        connections, this option looks at the Proxy-Authorization and
        X-Tor-Stream-Isolation headers. On by default;
        you can disable it with **NoIsolateSOCKSAuth**.)
    **IsolateClientProtocol**;;
        Don't share circuits with streams using a different protocol.
        (SOCKS 4, SOCKS 5, HTTPTunnelPort connections, TransPort connections,
        NATDPort connections, and DNSPort requests are all considered to be
        different protocols.)
    **IsolateDestPort**;;
        Don't share circuits with streams targeting a different
        destination port.
    **IsolateDestAddr**;;
        Don't share circuits with streams targeting a different
        destination address.
    **KeepAliveIsolateSOCKSAuth**;;
        If **IsolateSOCKSAuth** is enabled, keep alive circuits while they have
        at least one stream with SOCKS authentication active. After such a
        circuit is idle for more than MaxCircuitDirtiness seconds, it can be
        closed.
    **SessionGroup=**__INT__;;
        If no other isolation rules would prevent it, allow streams
        on this port to share circuits with streams from every other
        port with the same session group.  (By default, streams received
        on different SocksPorts, TransPorts, etc are always isolated from one
        another. This option overrides that behavior.)

// Anchor only for formatting, not visible in the man page.
[[OtherSocksPortFlags]]::
    Other recognized __flags__ for a SocksPort are:
    **NoIPv4Traffic**;;
        Tell exits to not connect to IPv4 addresses in response to SOCKS
        requests on this connection.
    **IPv6Traffic**;;
        Tell exits to allow IPv6 addresses in response to SOCKS requests on
        this connection, so long as SOCKS5 is in use.  (SOCKS4 can't handle
        IPv6.)
    **PreferIPv6**;;
        Tells exits that, if a host has both an IPv4 and an IPv6 address,
        we would prefer to connect to it via IPv6. (IPv4 is the default.)
    **NoDNSRequest**;;
        Do not ask exits to resolve DNS addresses in SOCKS5 requests. Tor will
        connect to IPv4 addresses, IPv6 addresses (if IPv6Traffic is set) and
        .onion addresses.
    **NoOnionTraffic**;;
        Do not connect to .onion addresses in SOCKS5 requests.
    **OnionTrafficOnly**;;
        Tell the tor client to only connect to .onion addresses in response to
        SOCKS5 requests on this connection. This is equivalent to NoDNSRequest,
        NoIPv4Traffic, NoIPv6Traffic. The corresponding NoOnionTrafficOnly
        flag is not supported.
    **CacheIPv4DNS**;;
        Tells the client to remember IPv4 DNS answers we receive from exit
        nodes via this connection.
    **CacheIPv6DNS**;;
        Tells the client to remember IPv6 DNS answers we receive from exit
        nodes via this connection.
    **GroupWritable**;;
        Unix domain sockets only: makes the socket get created as
        group-writable.
    **WorldWritable**;;
        Unix domain sockets only: makes the socket get created as
        world-writable.
    **CacheDNS**;;
        Tells the client to remember all DNS answers we receive from exit
        nodes via this connection.
    **UseIPv4Cache**;;
        Tells the client to use any cached IPv4 DNS answers we have when making
        requests via this connection. (NOTE: This option, or UseIPv6Cache
        or UseDNSCache, can harm your anonymity, and probably
        won't help performance as much as you might expect. Use with care!)
    **UseIPv6Cache**;;
        Tells the client to use any cached IPv6 DNS answers we have when making
        requests via this connection.
    **UseDNSCache**;;
        Tells the client to use any cached DNS answers we have when making
        requests via this connection.
    **NoPreferIPv6Automap**;;
        When serving a hostname lookup request on this port that
        should get automapped (according to AutomapHostsOnResolve),
        if we could return either an IPv4 or an IPv6 answer, prefer
        an IPv4 answer. (Tor prefers IPv6 by default.)
    **PreferSOCKSNoAuth**;;
        Ordinarily, when an application offers both "username/password
        authentication" and "no authentication" to Tor via SOCKS5, Tor
        selects username/password authentication so that IsolateSOCKSAuth can
        work.  This can confuse some applications, if they offer a
        username/password combination then get confused when asked for
        one. You can disable this behavior, so that Tor will select "No
        authentication" when IsolateSOCKSAuth is disabled, or when this
        option is set.
    **ExtendedErrors**;;
        Return extended error code in the SOCKS reply. So far, the possible
        errors are:

          X'F0' Onion Service Descriptor Can Not be Found

            The requested onion service descriptor can't be found on the
            hashring and thus not reachable by the client. (v3 only)

          X'F1' Onion Service Descriptor Is Invalid

            The requested onion service descriptor can't be parsed or
            signature validation failed. (v3 only)

          X'F2' Onion Service Introduction Failed

            All introduction attempts failed either due to a combination of
            NACK by the intro point or time out. (v3 only)

          X'F3' Onion Service Rendezvous Failed

            Every rendezvous circuit has timed out and thus the client is
            unable to rendezvous with the service. (v3 only)

          X'F4' Onion Service Missing Client Authorization

            Client was able to download the requested onion service descriptor
            but is unable to decrypt its content because it is missing client
            authorization information. (v3 only)

          X'F5' Onion Service Wrong Client Authorization

            Client was able to download the requested onion service descriptor
            but is unable to decrypt its content using the client
            authorization information it has. This means the client access
            were revoked. (v3 only)

          X'F6' Onion Service Invalid Address

            The given .onion address is invalid. In one of these cases this
            error is returned: address checksum doesn't match, ed25519 public
            key is invalid or the encoding is invalid. (v3 only)

          X'F7' Onion Service Introduction Timed Out

            Similar to X'F2' code but in this case, all introduction attempts
            have failed due to a time out. (v3 only)

// Anchor only for formatting, not visible in the man page.
[[SocksPortFlagsMisc]]::
    Flags are processed left to right. If flags conflict, the last flag on the
    line is used, and all earlier flags are ignored. No error is issued for
    conflicting flags.

[[TokenBucketRefillInterval]] **TokenBucketRefillInterval** __NUM__ [**msec**|**second**]::
    Set the refill delay interval of Tor's token bucket to NUM milliseconds.
    NUM must be between 1 and 1000, inclusive.  When Tor is out of bandwidth,
    on a connection or globally, it will wait up to this long before it tries
    to use that connection again.
    Note that bandwidth limits are still expressed in bytes per second: this
    option only affects the frequency with which Tor checks to see whether
    previously exhausted connections may read again.
    Can not be changed while tor is running. (Default: 100 msec)

[[TrackHostExits]] **TrackHostExits** __host__,__.domain__,__...__::
    For each value in the comma separated list, Tor will track recent
    connections to hosts that match this value and attempt to reuse the same
    exit node for each. If the value is prepended with a \'.\', it is treated as
    matching an entire domain. If one of the values is just a \'.', it means
    match everything. This option is useful if you frequently connect to sites
    that will expire all your authentication cookies (i.e. log you out) if
    your IP address changes. Note that this option does have the disadvantage
    of making it more clear that a given history is associated with a single
    user. However, most people who would wish to observe this will observe it
    through cookies or other protocol-specific means anyhow.

[[TrackHostExitsExpire]] **TrackHostExitsExpire** __NUM__::
    Since exit servers go up and down, it is desirable to expire the
    association between host and exit server after NUM seconds. The default is
    1800 seconds (30 minutes).

[[TransPort]] **TransPort** ['address'**:**]{empty}__port__|**auto** [_isolation flags_]::
    Open this port to listen for transparent proxy connections.  Set this to
    0 if you don't want to allow transparent proxy connections.  Set the port
    to "auto" to have Tor pick a port for you. This directive can be
    specified multiple times to bind to multiple addresses/ports. If multiple
    entries of this option are present in your configuration file, Tor will
    perform stream isolation between listeners by default.  See
    <<SocksPort,SocksPort>> for an explanation of isolation flags. +
     +
    TransPort requires OS support for transparent proxies, such as BSDs' pf or
    Linux's IPTables. If you're planning to use Tor as a transparent proxy for
    a network, you'll want to examine and change VirtualAddrNetwork from the
    default setting. (Default: 0)

[[TransProxyType]] **TransProxyType** **default**|**TPROXY**|**ipfw**|**pf-divert**::
    TransProxyType may only be enabled when there is transparent proxy listener
    enabled. +
     +
    Set this to "TPROXY" if you wish to be able to use the TPROXY Linux module
    to transparently proxy connections that are configured using the TransPort
    option. Detailed information on how to configure the TPROXY
    feature can be found in the Linux kernel source tree in the file
    Documentation/networking/tproxy.txt. +
     +
    Set this option to "ipfw" to use the FreeBSD ipfw interface. +
     +
    On *BSD operating systems when using pf, set this to "pf-divert" to take
    advantage of +divert-to+ rules, which do not modify the packets like
    +rdr-to+ rules do. Detailed information on how to configure pf to use
    +divert-to+ rules can be found in the pf.conf(5) manual page. On OpenBSD,
    +divert-to+ is available to use on versions greater than or equal to
    OpenBSD 4.4. +
     +
    Set this to "default", or leave it unconfigured, to use regular IPTables
    on Linux, or to use pf +rdr-to+ rules on *BSD systems. +
     +
    (Default: "default")

[[UpdateBridgesFromAuthority]] **UpdateBridgesFromAuthority** **0**|**1**::
    When set (along with UseBridges), Tor will try to fetch bridge descriptors
    from the configured bridge authorities when feasible. It will fall back to
    a direct request if the authority responds with a 404. (Default: 0)

[[UseBridges]] **UseBridges** **0**|**1**::
    When set, Tor will fetch descriptors for each bridge listed in the "Bridge"
    config lines, and use these relays as both entry guards and directory
    guards. (Default: 0)

[[UseEntryGuards]] **UseEntryGuards** **0**|**1**::
    If this option is set to 1, we pick a few long-term entry servers, and try
    to stick with them. This is desirable because constantly changing servers
    increases the odds that an adversary who owns some servers will observe a
    fraction of your paths. Entry Guards can not be used by Directory
    Authorities or Single Onion Services. In these cases,
    this option is ignored. (Default: 1)

[[UseGuardFraction]] **UseGuardFraction** **0**|**1**|**auto**::
    This option specifies whether clients should use the
    guardfraction information found in the consensus during path
    selection. If it's set to 'auto', clients will do what the
    UseGuardFraction consensus parameter tells them to do. (Default: auto)

//Out of order because it logically belongs after the UseEntryGuards option
[[GuardLifetime]] **GuardLifetime**  __N__ **days**|**weeks**|**months**::
    If UseEntryGuards is set, minimum time to keep a guard on our guard list
    before  picking a new one.  If less than one day, we use defaults from the
    consensus directory.  (Default: 0)

//Out of order because it logically belongs after the UseEntryGuards option
[[NumDirectoryGuards]] **NumDirectoryGuards** __NUM__::
    If UseEntryGuards is set to 1, we try to make sure we have at least NUM
    routers to use as directory guards. If this option is set to 0, use the
    value from the guard-n-primary-dir-guards-to-use consensus parameter, and
    default to 3 if the consensus parameter isn't set.  (Default: 0)

//Out of order because it logically belongs after the UseEntryGuards option
[[NumEntryGuards]] **NumEntryGuards** __NUM__::
    If UseEntryGuards is set to 1, we will try to pick a total of NUM routers
    as long-term entries for our circuits. If NUM is 0, we try to learn the
    number from the guard-n-primary-guards-to-use consensus parameter, and
    default to 1 if the consensus parameter isn't set. (Default: 0)

//Out of order because it logically belongs after the UseEntryGuards option
[[NumPrimaryGuards]] **NumPrimaryGuards** __NUM__::
    If UseEntryGuards is set to 1, we will try to pick NUM routers for our
    primary guard list, which is the set of routers we strongly prefer when
    connecting to the Tor network. If NUM is 0, we try to learn the number from
    the guard-n-primary-guards consensus parameter, and default to 3 if the
    consensus parameter isn't set. (Default: 0)

[[VanguardsLiteEnabled]] **VanguardsLiteEnabled** **0**|**1**|**auto**::
    This option specifies whether clients should use the vanguards-lite
    subsystem to protect against guard discovery attacks. If it's set to
    'auto', clients will do what the vanguards-lite-enabled consensus parameter
    tells them to do, and will default to enable the subsystem if the consensus
    parameter isn't set. (Default: auto)

[[UseMicrodescriptors]] **UseMicrodescriptors** **0**|**1**|**auto**::
    Microdescriptors are a smaller version of the information that Tor needs
    in order to build its circuits.  Using microdescriptors makes Tor clients
    download less directory information, thus saving bandwidth.  Directory
    caches need to fetch regular descriptors and microdescriptors, so this
    option doesn't save any bandwidth for them.  For legacy reasons, auto is
    accepted, but it has the same effect as 1. (Default: auto)

[[VirtualAddrNetworkIPv4]] **VirtualAddrNetworkIPv4** __IPv4Address__/__bits__ +

[[VirtualAddrNetworkIPv6]] **VirtualAddrNetworkIPv6** [__IPv6Address__]/__bits__::
    When Tor needs to assign a virtual (unused) address because of a MAPADDRESS
    command from the controller or the AutomapHostsOnResolve feature, Tor
    picks an unassigned address from this range. (Defaults:
    127.192.0.0/10 and [FE80::]/10 respectively.) +
     +
    When providing proxy server service to a network of computers using a tool
    like dns-proxy-tor, change the IPv4 network to "10.192.0.0/10" or
    "172.16.0.0/12" and change the IPv6 network to "[FC00::]/7".
    The default **VirtualAddrNetwork** address ranges on a
    properly configured machine will route to the loopback or link-local
    interface. The maximum number of bits for the network prefix is set to 104
    for IPv6 and 16 for IPv4. However, a larger network
    (that is, one with a smaller prefix length)
    is preferable, since it reduces the chances for an attacker to guess the
    used IP. For local use, no change to the default VirtualAddrNetwork setting
    is needed.

== CIRCUIT TIMEOUT OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

The following options are useful for configuring timeouts related
to building Tor circuits and using them:

[[CircuitsAvailableTimeout]] **CircuitsAvailableTimeout** __NUM__::
    Tor will attempt to keep at least one open, unused circuit available for
    this amount of time. This option governs how long idle circuits are kept
    open, as well as the amount of time Tor will keep a circuit open to each
    of the recently used ports. This way when the Tor client is entirely
    idle, it can expire all of its circuits, and then expire its TLS
    connections. Note that the actual timeout value is uniformly randomized
    from the specified value to twice that amount. (Default: 30 minutes;
    Max: 24 hours)

// Out of order because it logically belongs before the CircuitBuildTimeout option
[[LearnCircuitBuildTimeout]] **LearnCircuitBuildTimeout** **0**|**1**::
    If 0, CircuitBuildTimeout adaptive learning is disabled. (Default: 1)

[[CircuitBuildTimeout]] **CircuitBuildTimeout** __NUM__::
    Try for at most NUM seconds when building circuits. If the circuit isn't
    open in that time, give up on it. If LearnCircuitBuildTimeout is 1, this
    value serves as the initial value to use before a timeout is learned. If
    LearnCircuitBuildTimeout is 0, this value is the only value used.
    (Default: 60 seconds)

[[CircuitStreamTimeout]] **CircuitStreamTimeout** __NUM__::
    If non-zero, this option overrides our internal timeout schedule for how
    many seconds until we detach a stream from a circuit and try a new circuit.
    If your network is particularly slow, you might want to set this to a
    number like 60. (Default: 0)

[[SocksTimeout]] **SocksTimeout** __NUM__::
    Let a socks connection wait NUM seconds handshaking, and NUM seconds
    unattached waiting for an appropriate circuit, before we fail it. (Default:
    2 minutes)

== DORMANT MODE OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

Tor can enter dormant mode to conserve power and network bandwidth.
The following options control when Tor enters and leaves dormant mode:

[[DormantCanceledByStartup]] **DormantCanceledByStartup** **0**|**1**::
    By default, Tor starts in active mode if it was active the last time
    it was shut down, and in dormant mode if it was dormant.  But if
    this option is true, Tor treats every startup event as user
    activity, and Tor will never start in Dormant mode, even if it has
    been unused for a long time on previous runs. (Default: 0)
     +
    Note: Packagers and application developers should change the value of
    this option only with great caution: it has the potential to
    create spurious traffic on the network.  This option should only
    be used if Tor is started by an affirmative user activity (like
    clicking on an application or running a command), and not if Tor
    is launched for some other reason (for example, by a startup
    process, or by an application that launches itself on every login.)

[[DormantClientTimeout]] **DormantClientTimeout**  __N__ **minutes**|**hours**|**days**|**weeks**::
    If Tor spends this much time without any client activity,
    enter a dormant state where automatic circuits are not built, and
    directory information is not fetched.
    Does not affect servers or onion services. Must be at least 10 minutes.
    (Default: 24 hours)

[[DormantOnFirstStartup]] **DormantOnFirstStartup** **0**|**1**::
    If true, then the first time Tor starts up with a fresh DataDirectory,
    it starts in dormant mode, and takes no actions until the user has made
    a request.  (This mode is recommended if installing a Tor client for a
    user who might not actually use it.)  If false, Tor bootstraps the first
    time it is started, whether it sees a user request or not.
     +
    After the first time Tor starts, it begins in dormant mode if it was
    dormant before, and not otherwise. (Default: 0)

[[DormantTimeoutDisabledByIdleStreams]] **DormantTimeoutDisabledByIdleStreams**  **0**|**1**::
    If true, then any open client stream (even one not reading or writing)
    counts as client activity for the purpose of DormantClientTimeout.
    If false, then only network activity counts. (Default: 1)

[[DormantTimeoutEnabled]] **DormantTimeoutEnabled** **0**|**1**::
    If false, then no amount of time without activity is sufficient to
    make Tor go dormant.  Setting this option to zero is only recommended for
    special-purpose applications that need to use the Tor binary for
    something other than sending or receiving Tor traffic. (Default: 1)

== NODE SELECTION OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

The following options restrict the nodes that a tor client
(or onion service) can use while building a circuit.
These options can weaken your anonymity by making your client behavior
different from other Tor clients:

[[EntryNodes]] **EntryNodes** __node__,__node__,__...__::
    A list of identity fingerprints and country codes of nodes
    to use for the first hop in your normal circuits.
    Normal circuits include all
    circuits except for direct connections to directory servers.  The Bridge
    option overrides this option; if you have configured bridges and
    UseBridges is 1, the Bridges are used as your entry nodes. +
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
    The ExcludeNodes option overrides this option: any node listed in both
    EntryNodes and ExcludeNodes is treated as excluded. See
    <<ExcludeNodes,ExcludeNodes>> for more information on how to specify nodes.

[[ExcludeNodes]] **ExcludeNodes** __node__,__node__,__...__::
    A list of identity fingerprints, country codes, and address
    patterns of nodes to avoid when building a circuit. Country codes are
    2-letter ISO3166 codes, and must
    be wrapped in braces; fingerprints may be preceded by a dollar sign.
    (Example:
    ExcludeNodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, \{cc}, 255.254.0.0/8) +
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
    By default, this option is treated as a preference that Tor is allowed
    to override in order to keep working.
    For example, if you try to connect to a hidden service,
    but you have excluded all of the hidden service's introduction points,
    Tor will connect to one of them anyway.  If you do not want this
    behavior, set the StrictNodes option (documented below).  +
     +
    Note also that if you are a relay, this (and the other node selection
    options below) only affects your own circuits that Tor builds for you.
    Clients can still build circuits through you to any node.  Controllers
    can tell Tor to build circuits through any node. +
     +
    Country codes are case-insensitive. The code "\{??}" refers to nodes whose
    country can't be identified. No country code, including \{??}, works if
    no GeoIPFile can be loaded. See also the <<GeoIPExcludeUnknown,GeoIPExcludeUnknown>> option below.

// Out of order because it logically belongs after the ExcludeNodes option
[[ExcludeExitNodes]] **ExcludeExitNodes** __node__,__node__,__...__::
    A list of identity fingerprints, country codes, and address
    patterns of nodes to never use when picking an exit node---that is, a
    node that delivers traffic for you *outside* the Tor network.   Note that any
    node listed in ExcludeNodes is automatically considered to be part of this
    list too.  See
    <<ExcludeNodes,ExcludeNodes>> for more information on how to specify
    nodes. See also the caveats on the <<ExitNodes,ExitNodes>> option below.
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
[[ExitNodes]] **ExitNodes** __node__,__node__,__...__::
    A list of identity fingerprints, country codes, and address
    patterns of nodes to use as exit node---that is, a
    node that delivers traffic for you *outside* the Tor network.  See
    <<ExcludeNodes,ExcludeNodes>> for more information on how to specify nodes. +
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
    Note that if you list too few nodes here, or if you exclude too many exit
    nodes with ExcludeExitNodes, you can degrade functionality.  For example,
    if none of the exits you list allows traffic on port 80 or 443, you won't
    be able to browse the web. +
     +
    Note also that not every circuit is used to deliver traffic *outside* of
    the Tor network.  It is normal to see non-exit circuits (such as those
    used to connect to hidden services, those that do directory fetches,
    those used for relay reachability self-tests, and so on) that end
    at a non-exit node.  To
    keep a node from being used entirely, see <<ExcludeNodes,ExcludeNodes>> and <<StrictNodes,StrictNodes>>. +
     +
    The ExcludeNodes option overrides this option: any node listed in both
    ExitNodes and ExcludeNodes is treated as excluded. +
     +
    The .exit address notation, if enabled via MapAddress, overrides
    this option.

[[GeoIPExcludeUnknown]] **GeoIPExcludeUnknown** **0**|**1**|**auto**::
    If this option is set to 'auto', then whenever any country code is set in
    ExcludeNodes or ExcludeExitNodes, all nodes with unknown country (\{??} and
    possibly \{A1}) are treated as excluded as well. If this option is set to
    '1', then all unknown countries are treated as excluded in ExcludeNodes
    and ExcludeExitNodes.  This option has no effect when a GeoIP file isn't
    configured or can't be found.  (Default: auto)

[[HSLayer2Nodes]] **HSLayer2Nodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes, and
    address patterns of nodes that are allowed to be used as the
    second hop in all client or service-side Onion Service circuits.
    This option mitigates attacks where the adversary runs middle nodes
    and induces your client or service to create many circuits, in order
    to discover your primary guard node.
    (Default: Any node in the network may be used in the second hop.)
     +
    (Example:
    HSLayer2Nodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, \{cc}, 255.254.0.0/8) +
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
    When this is set, the resulting hidden service paths will
    look like:
     +
        C - G - L2 - M - Rend +
        C - G - L2 - M - HSDir +
        C - G - L2 - M - Intro +
        S - G - L2 - M - Rend +
        S - G - L2 - M - HSDir +
        S - G - L2 - M - Intro +
     +
    where C is this client, S is the service, G is the Guard node,
    L2 is a node from this option, and M is a random middle node.
    Rend, HSDir, and Intro point selection is not affected by this
    option.
     +
    This option may be combined with HSLayer3Nodes to create
    paths of the form:
     +
        C - G - L2 - L3 - Rend +
        C - G - L2 - L3 - M - HSDir +
        C - G - L2 - L3 - M - Intro +
        S - G - L2 - L3 - M - Rend +
        S - G - L2 - L3 - HSDir +
        S - G - L2 - L3 - Intro +
     +
    ExcludeNodes have higher priority than HSLayer2Nodes,
    which means that nodes specified in ExcludeNodes will not be
    picked.
     +
    When either this option or HSLayer3Nodes are set, the /16 subnet
    and node family restrictions are removed for hidden service
    circuits. Additionally, we allow the guard node to be present
    as the Rend, HSDir, and IP node, and as the hop before it. This
    is done to prevent the adversary from inferring information
    about our guard, layer2, and layer3 node choices at later points
    in the path.
     +
    This option is meant to be managed by a Tor controller such as
    https://github.com/mikeperry-tor/vanguards that selects and
    updates this set of nodes for you. Hence it does not do load
    balancing if fewer than 20 nodes are selected, and if no nodes in
    HSLayer2Nodes are currently available for use, Tor will not work.
    Please use extreme care if you are setting this option manually.

[[HSLayer3Nodes]] **HSLayer3Nodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes, and
    address patterns of nodes that are allowed to be used as the
    third hop in all client and service-side Onion Service circuits.
    This option mitigates attacks where the adversary runs middle nodes
    and induces your client or service to create many circuits, in order
    to discover your primary or Layer2 guard nodes.
    (Default: Any node in the network may be used in the third hop.)
     +
    (Example:
    HSLayer3Nodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, \{cc}, 255.254.0.0/8) +
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
    When this is set by itself, the resulting hidden service paths
    will look like: +
        C - G - M - L3 - Rend +
        C - G - M - L3 - M - HSDir +
        C - G - M - L3 - M - Intro +
        S - G - M - L3 - M - Rend +
        S - G - M - L3 - HSDir +
        S - G - M - L3 - Intro +
    where C is this client, S is the service, G is the Guard node,
    L2 is a node from this option, and M is a random middle node.
    Rend, HSDir, and Intro point selection is not affected by this
    option.
     +
    While it is possible to use this option by itself, it should be
    combined with HSLayer2Nodes to create paths of the form:
     +
        C - G - L2 - L3 - Rend +
        C - G - L2 - L3 - M - HSDir +
        C - G - L2 - L3 - M - Intro +
        S - G - L2 - L3 - M - Rend +
        S - G - L2 - L3 - HSDir +
        S - G - L2 - L3 - Intro +
     +
    ExcludeNodes have higher priority than HSLayer3Nodes,
    which means that nodes specified in ExcludeNodes will not be
    picked.
     +
    When either this option or HSLayer2Nodes are set, the /16 subnet
    and node family restrictions are removed for hidden service
    circuits. Additionally, we allow the guard node to be present
    as the Rend, HSDir, and IP node, and as the hop before it. This
    is done to prevent the adversary from inferring information
    about our guard, layer2, and layer3 node choices at later points
    in the path.
  +
    This option is meant to be managed by a Tor controller such as
    https://github.com/mikeperry-tor/vanguards that selects and
    updates this set of nodes for you. Hence it does not do load
    balancing if fewer than 20 nodes are selected, and if no nodes in
    HSLayer3Nodes are currently available for use, Tor will not work.
    Please use extreme care if you are setting this option manually.

[[MiddleNodes]] **MiddleNodes** __node__,__node__,__...__::
    A list of identity fingerprints and country codes of nodes
    to use for "middle" hops in your normal circuits.
    Normal circuits include all circuits except for direct connections
    to directory servers. Middle hops are all hops other than exit and entry.
     +
    This option can appear multiple times: the values from multiple lines are
    spliced together. +
     +
    This is an **experimental** feature that is meant to be used by researchers
    and developers to test new features in the Tor network safely. Using it
    without care will strongly influence your anonymity. Other tor features may
    not work with MiddleNodes. This feature might get removed in the future.
+
    The HSLayer2Node and HSLayer3Node options override this option for onion
    service circuits, if they are set. The vanguards addon will read this
    option, and if set, it will set HSLayer2Nodes and HSLayer3Nodes to nodes
    from this set.
+
    The ExcludeNodes option overrides this option: any node listed in both
    MiddleNodes and ExcludeNodes is treated as excluded. See
    the <<ExcludeNodes,ExcludeNodes>> for more information on how to specify nodes.

[[NodeFamily]] **NodeFamily** __node__,__node__,__...__::
    The Tor servers, defined by their identity fingerprints,
    constitute a "family" of similar or co-administered servers, so never use
    any two of them in the same circuit. Defining a NodeFamily is only needed
    when a server doesn't list the family itself (with MyFamily). This option
    can be used multiple times; each instance defines a separate family.  In
    addition to nodes, you can also list IP address and ranges and country
    codes in {curly braces}. See <<ExcludeNodes,ExcludeNodes>> for more
    information on how to specify nodes.

[[StrictNodes]] **StrictNodes** **0**|**1**::
    If StrictNodes is set to 1, Tor will treat solely the ExcludeNodes option
    as a requirement to follow for all the circuits you generate, even if
    doing so will break functionality for you (StrictNodes does not apply to
    ExcludeExitNodes, ExitNodes, MiddleNodes, or MapAddress).  If StrictNodes
    is set to 0, Tor will still try to avoid nodes in the ExcludeNodes list,
    but it will err on the side of avoiding unexpected errors.
    Specifically, StrictNodes 0 tells Tor that it is okay to use an excluded
    node when it is *necessary* to perform relay reachability self-tests,
    connect to a hidden service, provide a hidden service to a client,
    fulfill a .exit request, upload directory information, or download
    directory information.  (Default: 0)

[[server-options]]
== SERVER OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

The following options are useful only for servers (that is, if ORPort
is non-zero):

[[AccountingMax]] **AccountingMax** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    Limits the max number of bytes sent and received within a set time period
    using a given calculation rule (see <<AccountingStart,AccountingStart>> and <<AccountingRule,AccountingRule>>).
    Useful if you need to stay under a specific bandwidth. By default, the
    number used for calculation is the max of either the bytes sent or
    received. For example, with AccountingMax set to 1 TByte, a server
    could send 900 GBytes and receive 800 GBytes and continue running.
    It will only hibernate once one of the two reaches 1 TByte. This can
    be changed to use the sum of the both bytes received and sent by setting
    the AccountingRule option to "sum" (total bandwidth in/out). When the
    number of bytes remaining gets low, Tor will stop accepting new connections
    and circuits. When the number of bytes is exhausted, Tor will hibernate
    until some time in the next accounting period. To prevent all servers
    from waking at the same time, Tor will also wait until a random point
    in each period before waking up. If you have bandwidth cost issues,
    enabling hibernation is preferable to setting a low bandwidth, since
    it provides users with a collection of fast servers that are up some
    of the time, which is more useful than a set of slow servers that are
    always "available". +
     +
    Note that (as also described in the Bandwidth section) Tor uses
    powers of two, not powers of ten: 1 GByte is 1024*1024*1024, not
    one billion. Be careful: some internet service providers might count
    GBytes differently.

[[AccountingRule]] **AccountingRule** **sum**|**max**|**in**|**out**::
    How we determine when our AccountingMax has been reached (when we
    should hibernate) during a time interval. Set to "max" to calculate
    using the higher of either the sent or received bytes (this is the
    default functionality). Set to "sum" to calculate using the sent
    plus received bytes. Set to "in" to calculate using only the
    received bytes. Set to "out" to calculate using only the sent bytes.
    (Default: max)

[[AccountingStart]] **AccountingStart** **day**|**week**|**month** [__day__] __HH:MM__::
    Specify how long accounting periods last. If **month** is given,
    each accounting period runs from the time __HH:MM__ on the __dayth__ day of one
    month to the same day and time of the next. The relay will go at full speed,
    use all the quota you specify, then hibernate for the rest of the period. (The
    day must be between 1 and 28.) If **week** is given, each accounting period
    runs from the time __HH:MM__ of the __dayth__ day of one week to the same day
    and time of the next week, with Monday as day 1 and Sunday as day 7. If **day**
    is given, each accounting period runs from the time __HH:MM__ each day to the
    same time on the next day. All times are local, and given in 24-hour time.
    (Default: "month 1 0:00")

[[Address]] **Address** __address__::
    The address of this server, or a fully qualified domain name of this server
    that resolves to an address.  You can leave this unset, and Tor will try to
    guess your address.  If a domain name is provided, Tor will attempt to
    resolve it and use the underlying IPv4/IPv6 address as its publish address
    (taking precedence over the ORPort configuration). The publish address is
    the one used to tell clients and other servers where to find your Tor
    server; it doesn't affect the address that your server binds to.  To bind
    to a different address, use the ORPort and OutboundBindAddress options.

[[AddressDisableIPv6]] **AddressDisableIPv6** **0**|**1**::
   By default, Tor will attempt to find the IPv6 of the relay if there is no
   IPv4Only ORPort. If set, this option disables IPv6 auto discovery. This
   disables IPv6 address resolution, IPv6 ORPorts, and IPv6 reachability
   checks. Also, the relay won't publish an IPv6 ORPort in its
   descriptor. (Default: 0)

[[AssumeReachable]] **AssumeReachable** **0**|**1**::
    This option is used when bootstrapping a new Tor network. If set to 1,
    don't do self-reachability testing; just upload your server descriptor
    immediately. (Default: 0)

[[AssumeReachableIPv6]] **AssumeReachableIPv6** **0**|**1**|**auto**::
    Like **AssumeReachable**, but affects only the relay's own IPv6 ORPort.
    If this value is set to "auto", then Tor will look at **AssumeReachable**
    instead. (Default: auto)

[[BridgeRelay]] **BridgeRelay** **0**|**1**::
    Sets the relay to act as a "bridge" with respect to relaying connections
    from bridge users to the Tor network. It mainly causes Tor to publish a
    server descriptor to the bridge database, rather than
    to the public directory authorities. +
     +
    Note: make sure that no MyFamily lines are present in your torrc when
    relay is configured in bridge mode.

//Out of order because it logically belongs after BridgeRelay.
[[BridgeDistribution]] **BridgeDistribution** __string__::
    If set along with BridgeRelay, Tor will include a new line in its
    bridge descriptor which indicates to the BridgeDB service how it
    would like its bridge address to be given out. Set it to "none" if
    you want BridgeDB to avoid distributing your bridge address, or "any" to
    let BridgeDB decide.  See https://bridges.torproject.org/info for a more
    up-to-date list of options. (Default: any)

[[ContactInfo]] **ContactInfo** __email_address__::
    Administrative contact information for this relay or bridge. This line
    can be used to contact you if your relay or bridge is misconfigured or
    something else goes wrong. Note that we archive and publish all
    descriptors containing these lines and that Google indexes them, so
    spammers might also collect them. You may want to obscure the fact
    that it's an email address and/or generate a new address for this
    purpose. +
     +
    ContactInfo **must** be set to a working address if you run more than one
    relay or bridge.  (Really, everybody running a relay or bridge should set
    it.)

[[DisableOOSCheck]] **DisableOOSCheck** **0**|**1**::
    This option disables the code that closes connections when Tor notices
    that it is running low on sockets. Right now, it is on by default,
    since the existing out-of-sockets mechanism tends to kill OR connections
    more than it should. (Default: 1)

[[ExitPolicy]] **ExitPolicy** __policy__,__policy__,__...__::
    Set an exit policy for this server. Each policy is of the form
    "**accept[6]**|**reject[6]**  __ADDR__[/__MASK__][:__PORT__]". If /__MASK__ is
    omitted then this policy just applies to the host given. Instead of giving
    a host or network you can also use "\*" to denote the universe (0.0.0.0/0
    and ::/0), or \*4 to denote all IPv4 addresses, and \*6 to denote all IPv6
    addresses.
    __PORT__ can be a single port number, an interval of ports
    "__FROM_PORT__-__TO_PORT__", or "\*". If __PORT__ is omitted, that means
    "\*". +
     +
    For example, "accept 18.7.22.69:\*,reject 18.0.0.0/8:\*,accept \*:\*" would
    reject any IPv4 traffic destined for MIT except for web.mit.edu, and accept
    any other IPv4 or IPv6 traffic. +
     +
    Tor also allows IPv6 exit policy entries. For instance, "reject6 [FC00::]/7:\*"
    rejects all destinations that share 7 most significant bit prefix with
    address FC00::. Respectively, "accept6 [C000::]/3:\*" accepts all destinations
    that share 3 most significant bit prefix with address C000::. +
     +
    accept6 and reject6 only produce IPv6 exit policy entries. Using an IPv4
    address with accept6 or reject6 is ignored and generates a warning.
    accept/reject allows either IPv4 or IPv6 addresses. Use \*4 as an IPv4
    wildcard address, and \*6 as an IPv6 wildcard address. accept/reject *
    expands to matching IPv4 and IPv6 wildcard address rules. +
     +
    To specify all IPv4 and IPv6 internal and link-local networks (including
    0.0.0.0/8, 169.254.0.0/16, 127.0.0.0/8, 192.168.0.0/16, 10.0.0.0/8,
    172.16.0.0/12, [::]/8, [FC00::]/7, [FE80::]/10, [FEC0::]/10, [FF00::]/8,
    and [::]/127), you can use the "private" alias instead of an address.
    ("private" always produces rules for IPv4 and IPv6 addresses, even when
    used with accept6/reject6.) +
     +
    Private addresses are rejected by default (at the beginning of your exit
    policy), along with any configured primary public IPv4 and IPv6 addresses.
    These private addresses are rejected unless you set the
    ExitPolicyRejectPrivate config option to 0. For example, once you've done
    that, you could allow HTTP to 127.0.0.1 and block all other connections to
    internal networks with "accept 127.0.0.1:80,reject private:\*", though that
    may also allow connections to your own computer that are addressed to its
    public (external) IP address. See RFC 1918 and RFC 3330 for more details
    about internal and reserved IP address space. See
    <<ExitPolicyRejectLocalInterfaces,ExitPolicyRejectLocalInterfaces>> if you want to block every address on the
    relay, even those that aren't advertised in the descriptor. +
     +
    This directive can be specified multiple times so you don't have to put it
    all on one line. +
     +
    Policies are considered first to last, and the first match wins. If you
    want to allow the same ports on IPv4 and IPv6, write your rules using
    accept/reject \*. If you want to allow different ports on IPv4 and IPv6,
    write your IPv6 rules using accept6/reject6 \*6, and your IPv4 rules using
    accept/reject \*4. If you want to \_replace_ the default exit policy, end
    your exit policy with either a reject \*:* or an accept \*:*. Otherwise,
    you're \_augmenting_ (prepending to) the default exit policy. +
     +
    If you want to use a reduced exit policy rather than the default exit
    policy, set "ReducedExitPolicy 1". If you want to _replace_ the default
    exit policy with your custom exit policy, end your exit policy with either
    a reject *:* or an accept *:*. Otherwise, you're _augmenting_ (prepending
    to) the default or reduced exit policy. +
     +
    The default exit policy is:

       reject *:25
       reject *:119
       reject *:135-139
       reject *:445
       reject *:563
       reject *:1214
       reject *:4661-4666
       reject *:6346-6429
       reject *:6699
       reject *:6881-6999
       accept *:*

// Anchor only for formatting, not visible in the man page.
[[ExitPolicyDefault]]::
    Since the default exit policy uses accept/reject *, it applies to both
    IPv4 and IPv6 addresses.

[[ExitPolicyRejectLocalInterfaces]] **ExitPolicyRejectLocalInterfaces** **0**|**1**::
    Reject all IPv4 and IPv6 addresses that the relay knows about, at the
    beginning of your exit policy. This includes any OutboundBindAddress, the
    bind addresses of any port options, such as ControlPort or DNSPort, and any
    public IPv4 and IPv6 addresses on any interface on the relay. (If IPv6Exit
    is not set, all IPv6 addresses will be rejected anyway.)
    See above entry on <<ExitPolicy,ExitPolicy>>.
    This option is off by default, because it lists all public relay IP
    addresses in the ExitPolicy, even those relay operators might prefer not
    to disclose.
    (Default: 0)

[[ExitPolicyRejectPrivate]] **ExitPolicyRejectPrivate** **0**|**1**::
    Reject all private (local) networks, along with the relay's advertised
    public IPv4 and IPv6 addresses, at the beginning of your exit policy.
    See above entry on <<ExitPolicy,ExitPolicy>>.
    (Default: 1)

[[ExitRelay]] **ExitRelay** **0**|**1**|**auto**::
    Tells Tor whether to run as an exit relay.  If Tor is running as a
    non-bridge server, and ExitRelay is set to 1, then Tor allows traffic to
    exit according to the ExitPolicy option, the ReducedExitPolicy option,
    or the default ExitPolicy (if no other exit policy option is specified). +
     +
    If ExitRelay is set to 0, no traffic is allowed to exit, and the
    ExitPolicy, ReducedExitPolicy, and IPv6Exit options are ignored. +
     +
    If ExitRelay is set to "auto", then Tor checks the ExitPolicy,
    ReducedExitPolicy, and IPv6Exit options. If at least one of these options
    is set, Tor behaves as if ExitRelay were set to 1. If none of these exit
    policy options are set, Tor behaves as if ExitRelay were set to 0.
    (Default: auto)

[[ReevaluateExitPolicy]] **ReevaluateExitPolicy** **0**|**1**::
    If set, reevaluate the exit policy on existing connections when reloading
    configuration. +
     +
    When the exit policy of an exit node change while reloading configuration,
    connections made prior to this change could violate the new policy. By
    setting this to 1, Tor will check if such connections exist, and mark them
    for termination.
    (Default: 0)

[[ExtendAllowPrivateAddresses]] **ExtendAllowPrivateAddresses** **0**|**1**::
    When this option is enabled, Tor will connect to relays on localhost,
    RFC1918 addresses, and so on. In particular, Tor will make direct OR
    connections, and Tor routers allow EXTEND requests, to these private
    addresses. (Tor will always allow connections to bridges, proxies, and
    pluggable transports configured on private addresses.) Enabling this
    option can create security issues; you should probably leave it off.
    (Default: 0)

[[GeoIPFile]] **GeoIPFile** __filename__::
    A filename containing IPv4 GeoIP data, for use with by-country statistics.

[[GeoIPv6File]] **GeoIPv6File** __filename__::
    A filename containing IPv6 GeoIP data, for use with by-country statistics.

[[HeartbeatPeriod]] **HeartbeatPeriod**  __N__ **minutes**|**hours**|**days**|**weeks**::
    Log a heartbeat message every **HeartbeatPeriod** seconds. This is
    a log level __notice__ message, designed to let you know your Tor
    server is still alive and doing useful things. Settings this
    to 0 will disable the heartbeat. Otherwise, it must be at least 30
    minutes. (Default: 6 hours)

[[IPv6Exit]] **IPv6Exit** **0**|**1**::
    If set, and we are an exit node, allow clients to use us for IPv6 traffic.
    When this option is set and ExitRelay is auto, we act as if ExitRelay
    is 1. (Default: 0)

[[KeyDirectory]] **KeyDirectory** __DIR__::
    Store secret keys in DIR. Can not be changed while tor is
    running.
    (Default: the "keys" subdirectory of DataDirectory.)

[[KeyDirectoryGroupReadable]] **KeyDirectoryGroupReadable** **0**|**1**|**auto**::
    If this option is set to 0, don't allow the filesystem group to read the
    KeyDirectory. If the option is set to 1, make the KeyDirectory readable
    by the default GID. If the option is "auto", then we use the
    setting for DataDirectoryGroupReadable when the KeyDirectory is the
    same as the DataDirectory, and 0 otherwise. (Default: auto)

[[MainloopStats]] **MainloopStats** **0**|**1**::
    Log main loop statistics every **HeartbeatPeriod** seconds. This is a log
    level __notice__ message designed to help developers instrumenting Tor's
    main event loop. (Default: 0)

[[MaxMemInQueues]] **MaxMemInQueues**  __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**::
    This option configures a threshold above which Tor will assume that it
    needs to stop queueing or buffering data because it's about to run out of
    memory.  If it hits this threshold, it will begin killing circuits until
    it has recovered at least 10% of this memory.  Do not set this option too
    low, or your relay may be unreliable under load.  This option only
    affects some queues, so the actual process size will be larger than
    this.  If this option is set to 0, Tor will try to pick a reasonable
    default based on your system's physical memory.  (Default: 0)

[[MaxOnionQueueDelay]] **MaxOnionQueueDelay** __NUM__ [**msec**|**second**]::
    If we have more onionskins queued for processing than we can process in
    this amount of time, reject new ones. (Default: 1750 msec)

[[MyFamily]] **MyFamily** __fingerprint__,__fingerprint__,...::
    Declare that this Tor relay is controlled or administered by a group or
    organization identical or similar to that of the other relays, defined by
    their (possibly $-prefixed) identity fingerprints.
    This option can be repeated many times, for
    convenience in defining large families: all fingerprints in all MyFamily
    lines are merged into one list.
    When two relays both declare that they are in the
    same \'family', Tor clients will not use them in the same circuit. (Each
    relay only needs to list the other servers in its family; it doesn't need to
    list itself, but it won't hurt if it does.) Do not list any bridge relay as it would
    compromise its concealment. +
     +
    If you run more than one relay, the MyFamily option on each relay
    **must** list all other relays, as described above. +
     +
    Note: do not use MyFamily when configuring your Tor instance as a
    bridge.

[[Nickname]] **Nickname** __name__::
    Set the server's nickname to \'name'. Nicknames must be between 1 and 19
    characters inclusive, and must contain only the characters [a-zA-Z0-9].
    If not set, **Unnamed** will be used. Relays can always be uniquely identified
    by their identity fingerprints.

[[NumCPUs]] **NumCPUs** __num__::
    How many processes to use at once for decrypting onionskins and other
    parallelizable operations.  If this is set to 0, Tor will try to detect
    how many CPUs you have, defaulting to 1 if it can't tell.  (Default: 0)

[[OfflineMasterKey]] **OfflineMasterKey** **0**|**1**::
    If non-zero, the Tor relay will never generate or load its master secret
    key.  Instead, you'll have to use "tor --keygen" to manage the permanent
    ed25519 master identity key, as well as the corresponding temporary
    signing keys and certificates. (Default: 0)

[[ORPort]] **ORPort** ['address'**:**]{empty}__PORT__|**auto** [_flags_]::
    Advertise this port to listen for connections from Tor clients and
    servers.  This option is required to be a Tor server.
    Set it to "auto" to have Tor pick a port for you. Set it to 0 to not
    run an ORPort at all. This option can occur more than once. (Default: 0) +
     +
    Tor recognizes these flags on each ORPort:
    **NoAdvertise**;;
        By default, we bind to a port and tell our users about it. If
        NoAdvertise is specified, we don't advertise, but listen anyway.  This
        can be useful if the port everybody will be connecting to (for
        example, one that's opened on our firewall) is somewhere else.
    **NoListen**;;
        By default, we bind to a port and tell our users about it. If
        NoListen is specified, we don't bind, but advertise anyway.  This
        can be useful if something else  (for example, a firewall's port
        forwarding configuration) is causing connections to reach us.
    **IPv4Only**;;
        If the address is absent, or resolves to both an IPv4 and an IPv6
        address, only listen to the IPv4 address.
    **IPv6Only**;;
        If the address is absent, or resolves to both an IPv4 and an IPv6
        address, only listen to the IPv6 address.

// Anchor only for formatting, not visible in the man page.
[[ORPortFlagsExclusive]]::
    For obvious reasons, NoAdvertise and NoListen are mutually exclusive, and
    IPv4Only and IPv6Only are mutually exclusive.

[[PublishServerDescriptor]] **PublishServerDescriptor** **0**|**1**|**v3**|**bridge**,**...**::
    This option specifies which descriptors Tor will publish when acting as
    a relay. You can
    choose multiple arguments, separated by commas. +
     +
    If this option is set to 0, Tor will not publish its
    descriptors to any directories. (This is useful if you're testing
    out your server, or if you're using a Tor controller that handles
    directory publishing for you.) Otherwise, Tor will publish its
    descriptors of all type(s) specified. The default is "1", which
    means "if running as a relay or bridge, publish descriptors to the
    appropriate authorities". Other possibilities are "v3", meaning
    "publish as if you're a relay", and "bridge", meaning "publish as
    if you're a bridge".

[[ReducedExitPolicy]] **ReducedExitPolicy** **0**|**1**::
    If set, use a reduced exit policy rather than the default one. +
     +
    The reduced exit policy is an alternative to the default exit policy. It
    allows as many Internet services as possible while still blocking the
    majority of TCP ports. Currently, the policy allows approximately 65 ports.
    This reduces the odds that your node will be used for peer-to-peer
    applications. +
     +
    The reduced exit policy is:

        accept *:20-21
        accept *:22
        accept *:23
        accept *:43
        accept *:53
        accept *:79
        accept *:80-81
        accept *:88
        accept *:110
        accept *:143
        accept *:194
        accept *:220
        accept *:389
        accept *:443
        accept *:464
        accept *:465
        accept *:531
        accept *:543-544
        accept *:554
        accept *:563
        accept *:587
        accept *:636
        accept *:706
        accept *:749
        accept *:873
        accept *:902-904
        accept *:981
        accept *:989-990
        accept *:991
        accept *:992
        accept *:993
        accept *:994
        accept *:995
        accept *:1194
        accept *:1220
        accept *:1293
        accept *:1500
        accept *:1533
        accept *:1677
        accept *:1723
        accept *:1755
        accept *:1863
        accept *:2082
        accept *:2083
        accept *:2086-2087
        accept *:2095-2096
        accept *:2102-2104
        accept *:3128
        accept *:3389
        accept *:3690
        accept *:4321
        accept *:4643
        accept *:5050
        accept *:5190
        accept *:5222-5223
        accept *:5228
        accept *:5900
        accept *:6660-6669
        accept *:6679
        accept *:6697
        accept *:8000
        accept *:8008
        accept *:8074
        accept *:8080
        accept *:8082
        accept *:8087-8088
        accept *:8232-8233
        accept *:8332-8333
        accept *:8443
        accept *:8888
        accept *:9418
        accept *:9999
        accept *:10000
        accept *:11371
        accept *:19294
        accept *:19638
        accept *:50002
        accept *:64738
        reject *:*

    (Default: 0)

[[RefuseUnknownExits]] **RefuseUnknownExits** **0**|**1**|**auto**::
    Prevent nodes that don't appear in the consensus from exiting using this
    relay.  If the option is 1, we always block exit attempts from such
    nodes; if it's 0, we never do, and if the option is "auto", then we do
    whatever the authorities suggest in the consensus (and block if the consensus
    is quiet on the issue). (Default: auto)

[[ServerDNSAllowBrokenConfig]] **ServerDNSAllowBrokenConfig** **0**|**1**::
    If this option is false, Tor exits immediately if there are problems
    parsing the system DNS configuration or connecting to nameservers.
    Otherwise, Tor continues to periodically retry the system nameservers until
    it eventually succeeds. (Default: 1)

[[ServerDNSAllowNonRFC953Hostnames]] **ServerDNSAllowNonRFC953Hostnames** **0**|**1**::
    When this option is disabled, Tor does not try to resolve hostnames
    containing illegal characters (like @ and :) rather than sending them to an
    exit node to be resolved. This helps trap accidental attempts to resolve
    URLs and so on. This option only affects name lookups that your server does
    on behalf of clients. (Default: 0)

[[ServerDNSDetectHijacking]] **ServerDNSDetectHijacking** **0**|**1**::
    When this option is set to 1, we will test periodically to determine
    whether our local nameservers have been configured to hijack failing DNS
    requests (usually to an advertising site). If they are, we will attempt to
    correct this. This option only affects name lookups that your server does
    on behalf of clients. (Default: 1)

[[ServerDNSRandomizeCase]] **ServerDNSRandomizeCase** **0**|**1**::
    When this option is set, Tor sets the case of each character randomly in
    outgoing DNS requests, and makes sure that the case matches in DNS replies.
    This so-called "0x20 hack" helps resist some types of DNS poisoning attack.
    For more information, see "Increased DNS Forgery Resistance through
    0x20-Bit Encoding". This option only affects name lookups that your server
    does on behalf of clients. (Default: 1)

[[ServerDNSResolvConfFile]] **ServerDNSResolvConfFile** __filename__::
    Overrides the default DNS configuration with the configuration in
    __filename__. The file format is the same as the standard Unix
    "**resolv.conf**" file (7). This option, like all other ServerDNS options,
    only affects name lookups that your server does on behalf of clients.
    (Defaults to use the system DNS configuration or a localhost DNS service
    in case no nameservers are found in a given configuration.)

[[ServerDNSSearchDomains]] **ServerDNSSearchDomains** **0**|**1**::
    If set to 1, then we will search for addresses in the local search domain.
    For example, if this system is configured to believe it is in
    "example.com", and a client tries to connect to "www", the client will be
    connected to "www.example.com". This option only affects name lookups that
    your server does on behalf of clients. (Default: 0)

[[ServerDNSTestAddresses]] **ServerDNSTestAddresses** __hostname__,__hostname__,__...__::
    When we're detecting DNS hijacking, make sure that these __valid__ addresses
    aren't getting redirected. If they are, then our DNS is completely useless,
    and we'll reset our exit policy to "reject \*:*". This option only affects
    name lookups that your server does on behalf of clients. (Default:
    "www.google.com, www.mit.edu, www.yahoo.com, www.slashdot.org")

[[ServerTransportListenAddr]] **ServerTransportListenAddr** __transport__ __IP__:__PORT__::
    When this option is set, Tor will suggest __IP__:__PORT__ as the
    listening address of any pluggable transport proxy that tries to
    launch __transport__. (IPv4 addresses should written as-is; IPv6
    addresses should be wrapped in square brackets.) (Default: none)

[[ServerTransportOptions]] **ServerTransportOptions** __transport__ __k=v__ __k=v__ ...::
    When this option is set, Tor will pass the __k=v__ parameters to
    any pluggable transport proxy that tries to launch __transport__. +
    (Example: ServerTransportOptions obfs45 shared-secret=bridgepasswd cache=/var/lib/tor/cache) (Default: none)

[[ServerTransportPlugin]] **ServerTransportPlugin** __transport__ exec __path-to-binary__ [options]::
    The Tor relay launches the pluggable transport proxy in __path-to-binary__
    using __options__ as its command-line options, and expects to receive
    proxied client traffic from it. (Default: none)

[[ShutdownWaitLength]] **ShutdownWaitLength** __NUM__::
    When we get a SIGINT and we're a server, we begin shutting down:
    we close listeners and start refusing new circuits. After **NUM**
    seconds, we exit. If we get a second SIGINT, we exit immediately.
    (Default: 30 seconds)

[[SigningKeyLifetime]] **SigningKeyLifetime** __N__ **days**|**weeks**|**months**::
    For how long should each Ed25519 signing key be valid?  Tor uses a
    permanent master identity key that can be kept offline, and periodically
    generates new "signing" keys that it uses online.  This option
    configures their lifetime.
    (Default: 30 days)

[[SSLKeyLifetime]] **SSLKeyLifetime** __N__ **minutes**|**hours**|**days**|**weeks**::
    When creating a link certificate for our outermost SSL handshake,
    set its lifetime to this amount of time. If set to 0, Tor will choose
    some reasonable random defaults. (Default: 0)

== STATISTICS OPTIONS

// These options are in alphabetical order, with exceptions as noted.
// Please keep them that way!

Relays publish most statistics in a document called the
extra-info document. The following options affect the different
types of statistics that Tor relays collect and publish:

[[BridgeRecordUsageByCountry]] **BridgeRecordUsageByCountry** **0**|**1**::
    When this option is enabled and BridgeRelay is also enabled, and we have
    GeoIP data, Tor keeps a per-country count of how many client
    addresses have contacted it so that it can help the bridge authority guess
    which countries have blocked access to it. If ExtraInfoStatistics is
    enabled, it will be published as part of the extra-info document.
    (Default: 1)

[[CellStatistics]] **CellStatistics** **0**|**1**::
    Relays only.
    When this option is enabled, Tor collects statistics about cell
    processing (i.e. mean time a cell is spending in a queue, mean
    number of cells in a queue and mean number of processed cells per
    circuit) and writes them into disk every 24 hours. Onion router
    operators may use the statistics for performance monitoring.
    If ExtraInfoStatistics is enabled, it will published as part of
    the extra-info document. (Default: 0)

[[ConnDirectionStatistics]] **ConnDirectionStatistics** **0**|**1**::
    Relays only.
    When this option is enabled, Tor writes statistics on the amounts of
    traffic it passes between itself and other relays to disk every 24
    hours. Enables relay operators to monitor how much their relay is
    being used as middle node in the circuit. If ExtraInfoStatistics is
    enabled, it will be published as part of the extra-info document.
    (Default: 0)

[[DirReqStatistics]] **DirReqStatistics** **0**|**1**::
    Relays and bridges only.
    When this option is enabled, a Tor directory writes statistics on the
    number and response time of network status requests to disk every 24
    hours. Enables relay and bridge operators to monitor how much their
    server is being used by clients to learn about Tor network.
    If ExtraInfoStatistics is enabled, it will published as part of
    the extra-info document. (Default: 1)

[[EntryStatistics]] **EntryStatistics** **0**|**1**::
    Relays only.
    When this option is enabled, Tor writes statistics on the number of
    directly connecting clients to disk every 24 hours. Enables relay
    operators to monitor how much inbound traffic that originates from
    Tor clients passes through their server to go further down the
    Tor network. If ExtraInfoStatistics is enabled, it will be published
    as part of the extra-info document. (Default: 0)

[[ExitPortStatistics]] **ExitPortStatistics** **0**|**1**::
    Exit relays only.
    When this option is enabled, Tor writes statistics on the number of
    relayed bytes and opened stream per exit port to disk every 24 hours.
    Enables exit relay operators to measure and monitor amounts of traffic
    that leaves Tor network through their exit node. If ExtraInfoStatistics
    is enabled, it will be published as part of the extra-info document.
    (Default: 0)

[[ExtraInfoStatistics]] **ExtraInfoStatistics** **0**|**1**::
    When this option is enabled, Tor includes previously gathered statistics in
    its extra-info documents that it uploads to the directory authorities.
    Disabling this option also removes bandwidth usage statistics, and
    GeoIPFile and GeoIPv6File hashes from the extra-info file. Bridge
    ServerTransportPlugin lines are always included in the extra-info file,
    because they are required by BridgeDB.
    (Default: 1)

[[HiddenServiceStatistics]] **HiddenServiceStatistics** **0**|**1**::
    Relays and bridges only.
    When this option is enabled, a Tor relay writes obfuscated
    statistics on its role as hidden-service directory, introduction
    point, or rendezvous point to disk every 24 hours.  If ExtraInfoStatistics
    is enabled, it will be published as part of the extra-info document.
    (Default: 1)

[[OverloadStatistics]] **OverloadStatistics** *0**|**1**::
    Relays and bridges only.
    When this option is enabled, a Tor relay will write an overload general
    line in the server descriptor if the relay is considered overloaded.
    (Default: 1)
     +
    A relay is considered overloaded if at least one of these conditions is
    met:
        - A certain ratio of ntor onionskins are dropped.
        - The OOM was invoked.
        - TCP Port exhaustion.

     +
    If ExtraInfoStatistics is enabled, it can also put two more specific
    overload lines in the extra-info document if at least one of these
    conditions is met:
        - Connection rate limits have been reached (read and write side).
        - File descriptors are exhausted.

[[PaddingStatistics]] **PaddingStatistics** **0**|**1**::
    Relays and bridges only.
    When this option is enabled, Tor collects statistics for padding cells
    sent and received by this relay, in addition to total cell counts.
    These statistics are rounded, and omitted if traffic is low. This
    information is important for load balancing decisions related to padding.
    If ExtraInfoStatistics is enabled, it will be published
    as a part of the extra-info document. (Default: 1)

== DIRECTORY SERVER OPTIONS

The following options are useful only for directory servers. (Relays with
enough bandwidth automatically become directory servers; see <<DirCache,DirCache>> for
details.)

[[DirCache]] **DirCache** **0**|**1**::
    When this option is set, Tor caches all current directory documents except
    extra info documents, and accepts client requests for them. If
    **DownloadExtraInfo** is set, cached extra info documents are also cached.
    Setting **DirPort** is not required for **DirCache**, because clients
    connect via the ORPort by default. Setting either DirPort or BridgeRelay
    and setting DirCache to 0 is not supported.  (Default: 1)

[[DirPolicy]] **DirPolicy** __policy__,__policy__,__...__::
    Set an entrance policy for this server, to limit who can connect to the
    directory ports. The policies have the same form as exit policies above,
    except that port specifiers are ignored. Any address not matched by
    some entry in the policy is accepted.

[[DirPort]] **DirPort** ['address'**:**]{empty}__PORT__|**auto** [_flags_]::
    If this option is nonzero, advertise the directory service on this port.
    Set it to "auto" to have Tor pick a port for you.  This option can occur
    more than once, but only one advertised DirPort is supported: all
    but one DirPort must have the **NoAdvertise** flag set. (Default: 0) +
     +
    The same flags are supported here as are supported by ORPort. This port can
    only be IPv4.
     +
    As of Tor 0.4.6.1-alpha, non-authoritative relays (see
    AuthoritativeDirectory) will not publish the DirPort but will still listen
    on it. Clients don't use the DirPorts on relays, so it is safe for you
    to remove the DirPort from your torrc configuration.

[[DirPortFrontPage]] **DirPortFrontPage** __FILENAME__::
    When this option is set, it takes an HTML file and publishes it as "/" on
    the DirPort. Now relay operators can provide a disclaimer without needing
    to set up a separate webserver. There's a sample disclaimer in
    contrib/operator-tools/tor-exit-notice.html.

[[MaxConsensusAgeForDiffs]] **MaxConsensusAgeForDiffs**  __N__ **minutes**|**hours**|**days**|**weeks**::
    When this option is nonzero, Tor caches will not try to generate
    consensus diffs for any consensus older than this amount of time.
    If this option is set to zero, Tor will pick a reasonable default from
    the current networkstatus document.  You should not set this
    option unless your cache is severely low on disk space or CPU.
    If you need to set it, keeping it above 3 or 4 hours will help clients
    much more than setting it to zero.
    (Default: 0)


== DENIAL OF SERVICE MITIGATION OPTIONS

Tor has a series of built-in denial of service mitigation options that can be
individually enabled/disabled and fine-tuned, but by default Tor directory
authorities will define reasonable values for the network and no explicit
configuration is required to make use of these protections.

The following is a series of configuration options for relays and then options
for onion services and how they work.

The mitigations take place at relays, and are as follows:

  1. If a single client address makes too many concurrent connections (this is
     configurable via DoSConnectionMaxConcurrentCount), hang up on further
     connections.
     +
  2. If a single client IP address (v4 or v6) makes circuits too quickly
     (default values are more than 3 per second, with an allowed burst of 90,
     see <<DoSCircuitCreationRate,DoSCircuitCreationRate>> and
     <<DoSCircuitCreationBurst,DoSCircuitCreationBurst>>) while also having
     too many connections open (default is 3, see
     <<DoSCircuitCreationMinConnections,DoSCircuitCreationMinConnections>>),
     tor will refuse any new circuit (CREATE
     cells) for the next while (random value between 1 and 2 hours).
     +
  3. If a client asks to establish a rendezvous point to you directly (ex:
     Tor2Web client), ignore the request.

These defenses can be manually controlled by torrc options, but relays will
also take guidance from consensus parameters using these same names, so there's
no need to configure anything manually. In doubt, do not change those values.

The values set by the consensus, if any, can be found here:
https://consensus-health.torproject.org/#consensusparams

If any of the DoS mitigations are enabled, a heartbeat message will appear in
your log at NOTICE level which looks like:

    DoS mitigation since startup: 429042 circuits rejected, 17 marked addresses.
    2238 connections closed. 8052 single hop clients refused.

The following options are useful only for a public relay. They control the
Denial of Service mitigation subsystem described above.

//Out of order because it logically belongs before the other DoSCircuitCreation options.
[[DoSCircuitCreationEnabled]] **DoSCircuitCreationEnabled** **0**|**1**|**auto**::

    Enable circuit creation DoS mitigation. If set to 1 (enabled), tor will
    cache client IPs along with statistics in order to detect circuit DoS
    attacks. If an address is positively identified, tor will activate
    defenses against the address. See <<DoSCircuitCreationDefenseType,DoSCircuitCreationDefenseType>>
     option for more details.  This is a client to relay detection only. "auto" means
    use the consensus parameter. If not defined in the consensus, the value is 0.
    (Default: auto)

[[DoSCircuitCreationBurst]] **DoSCircuitCreationBurst** __NUM__::

    The allowed circuit creation burst per client IP address. If the circuit
    rate and the burst are reached, a client is marked as executing a circuit
    creation DoS. "0" means use the consensus parameter. If not defined in the
    consensus, the value is 90.
    (Default: 0)

[[DoSCircuitCreationDefenseTimePeriod]] **DoSCircuitCreationDefenseTimePeriod** __N__ **seconds**|**minutes**|**hours**::

    The base time period in seconds that the DoS defense is activated for. The
    actual value is selected randomly for each activation from N+1 to 3/2 * N.
    "0" means use the consensus parameter. If not defined in the consensus,
    the value is 3600 seconds (1 hour).
    (Default: 0)

[[DoSCircuitCreationDefenseType]] **DoSCircuitCreationDefenseType** __NUM__::

    This is the type of defense applied to a detected client address. The
    possible values are:
     +
      1: No defense.
     +
      2: Refuse circuit creation for the DoSCircuitCreationDefenseTimePeriod period of time.
     +
    "0" means use the consensus parameter. If not defined in the consensus, the value is 2.
    (Default: 0)

[[DoSCircuitCreationMinConnections]] **DoSCircuitCreationMinConnections** __NUM__::

    Minimum threshold of concurrent connections before a client address can be
    flagged as executing a circuit creation DoS. In other words, once a client
    address reaches the circuit rate and has a minimum of NUM concurrent
    connections, a detection is positive. "0" means use the consensus
    parameter. If not defined in the consensus, the value is 3.
    (Default: 0)

[[DoSCircuitCreationRate]] **DoSCircuitCreationRate** __NUM__::

    The allowed circuit creation rate per second applied per client IP
    address. If this option is 0, it obeys a consensus parameter. If not
    defined in the consensus, the value is 3.
    (Default: 0)

//out of order because it logically belongs before the other DoSConnection options.
[[DoSConnectionEnabled]] **DoSConnectionEnabled** **0**|**1**|**auto**::

    Enable the connection DoS mitigation. If set to 1 (enabled), for client
    address only, this allows tor to mitigate against large number of
    concurrent connections made by a single IP address. "auto" means use the
    consensus parameter. If not defined in the consensus, the value is 0.
    (Default: auto)

[[DoSConnectionDefenseType]] **DoSConnectionDefenseType** __NUM__::

    This is the type of defense applied to a detected client address for the
    connection mitigation. The possible values are:
     +
      1: No defense.
     +
      2: Immediately close new connections.
     +
    "0" means use the consensus parameter. If not defined in the consensus, the value is 2.
    (Default: 0)

[[DoSConnectionMaxConcurrentCount]] **DoSConnectionMaxConcurrentCount** __NUM__::

    The maximum threshold of concurrent connection from a client IP address.
    Above this limit, a defense selected by DoSConnectionDefenseType is
    applied. "0" means use the consensus parameter. If not defined in the
    consensus, the value is 100.
    (Default: 0)

[[DoSConnectionConnectRate]] **DoSConnectionConnectRate** __NUM__::

    The allowed rate of client connection from a single address per second.
    Coupled with the burst (see below), if the limit is reached, the address
    is marked and a defense is applied (DoSConnectionDefenseType) for a period
    of time defined by DoSConnectionConnectDefenseTimePeriod. If not defined
    or set to 0, it is controlled by a consensus parameter.
    (Default: 0)

[[DoSConnectionConnectBurst]] **DoSConnectionConnectBurst** __NUM__::

    The allowed burst of client connection from a single address per second.
    See the DoSConnectionConnectRate for more details on this detection. If
    not defined or set to 0, it is controlled by a consensus parameter.
    (Default: 0)

[[DoSConnectionConnectDefenseTimePeriod]] **DoSConnectionConnectDefenseTimePeriod** __N__ **seconds**|**minutes**|**hours**::

    The base time period in seconds that the client connection defense is
    activated for. The actual value is selected randomly for each activation
    from N+1 to 3/2 * N. If not defined or set to 0, it is controlled by a
    consensus parameter.
    (Default: 24 hours)

[[DoSRefuseSingleHopClientRendezvous]] **DoSRefuseSingleHopClientRendezvous** **0**|**1**|**auto**::

    Refuse establishment of rendezvous points for single hop clients. In other
    words, if a client directly connects to the relay and sends an
    ESTABLISH_RENDEZVOUS cell, it is silently dropped. "auto" means use the
    consensus parameter. If not defined in the consensus, the value is 0.
    (Default: auto)

The following options are useful only for a exit relay.

[[DoSStreamCreationEnabled]] **DoSStreamCreationEnabled** **0**|**1**|**auto**::

    Enable the stream DoS mitigation. If set to 1 (enabled), tor will apply
    rate limit on the creation of new streams and dns requests per circuit.
    "auto" means use the consensus parameter. If not defined in the consensus,
    the value is 0. (Default: auto)

[[DoSStreamCreationDefenseType]] **DoSStreamCreationDefenseType** __NUM__::

    This is the type of defense applied to a detected circuit or stream for the
    stream mitigation. The possible values are:
     +
      1: No defense.
     +
      2: Reject the stream or resolve request.
     +
      3: Close the circuit creating too many streams.
     +
    "0" means use the consensus parameter. If not defined in the consensus, the value is 2.
    (Default: 0)

[[DoSStreamCreationRate]] **DoSStreamCreationRate** __NUM__::

    The allowed rate of stream creation from a single circuit per second. Coupled
    with the burst (see below), if the limit is reached, actions can be taken
    against the stream or circuit (DoSStreamCreationDefenseType). If not defined or
    set to 0, it is controlled by a consensus parameter. If not defined in the
    consensus, the value is 100. (Default: 0)

[[DoSStreamCreationBurst]] **DoSStreamCreationBurst** __NUM__::

    The allowed burst of stream creation from a circuit per second.
    See the DoSStreamCreationRate for more details on this detection. If
    not defined or set to 0, it is controlled by a consensus parameter. If not
    defined in the consensus, the value is 300. (Default: 0)


For onion services, mitigations are a work in progress and multiple options
are currently available.

The introduction point defense is a rate limit on the number of introduction
requests that will be forwarded to a service by each of its honest
introduction point routers. This can prevent some types of overwhelming floods
from reaching the service, but it will also prevent legitimate clients from
establishing new connections.

The following options are per onion service:

[[HiddenServiceEnableIntroDoSDefense]] **HiddenServiceEnableIntroDoSDefense** **0**|**1**::
    Enable DoS defense at the intropoint level. When this is enabled, the
    rate and burst parameter (see below) will be sent to the intro point which
    will then use them to apply rate limiting for introduction request to this
    service.
  +
    The introduction point honors the consensus parameters except if this is
    specifically set by the service operator using this option. The service
    never looks at the consensus parameters in order to enable or disable this
    defense. (Default: 0)

//Out of order because it logically belongs after HiddenServiceEnableIntroDoSDefense.
[[HiddenServiceEnableIntroDoSBurstPerSec]] **HiddenServiceEnableIntroDoSBurstPerSec** __NUM__::
    The allowed client introduction burst per second at the introduction
    point. If this option is 0, it is considered infinite and thus if
    **HiddenServiceEnableIntroDoSDefense** is set, it then effectively
    disables the defenses. (Default: 200)

[[HiddenServiceEnableIntroDoSRatePerSec]] **HiddenServiceEnableIntroDoSRatePerSec** __NUM__::
    The allowed client introduction rate per second at the introduction
    point. If this option is 0, it is considered infinite and thus if
    **HiddenServiceEnableIntroDoSDefense** is set, it then effectively
    disables the defenses. (Default: 25)

The rate is the maximum number of clients a service will ask its introduction
points to allow every seconds. And the burst is a parameter that allows that
many within one second.

For example, the default values of 25 and 200 respectively means that for every
introduction points a service has (default 3 but can be configured with
**HiddenServiceNumIntroductionPoints**), 25 clients per seconds will be allowed
to reach the service and 200 at most within 1 second as a burst. This means
that if 200 clients are seen within 1 second, it will take 8 seconds (200/25)
for another client to be able to be allowed to introduce due to the rate of 25
per second.

This might be too much for your use case or not, fine tuning these values is
hard and are likely different for each service operator.

Why is this not helping reachability of the service? Because the defenses are
at the introduction point, an attacker can easily flood all introduction point
rendering the service unavailable due to no client being able to pass through.
But, the service itself is not overwhelmed with connections allowing it to
function properly for the few clients that were able to go through or other any
services running on the same tor instance.

The bottom line is that this protects the network by preventing an onion
service to flood the network with new rendezvous circuits that is reducing load
on the network.

A secondary mitigation is available, based on prioritized dispatch of rendezvous
circuits for new connections. The queue is ordered based on effort a client
chooses to spend at computing a proof-of-work function.

The following options are per onion service:

[[HiddenServicePoWDefensesEnabled]] **HiddenServicePoWDefensesEnabled** **0**|**1**::

    Enable proof-of-work based service DoS mitigation. If set to 1 (enabled),
    tor will include parameters for an optional client puzzle in the encrypted
    portion of this hidden service's descriptor. Incoming rendezvous requests
    will be prioritized based on the amount of effort a client chooses to make
    when computing a solution to the puzzle. The service will periodically update
    a suggested amount of effort, based on attack load, and disable the puzzle
    entirely when the service is not overloaded.
    (Default: 0)

[[HiddenServicePoWQueueRate]] **HiddenServicePoWQueueRate** __NUM__::

    The sustained rate of rendezvous requests to dispatch per second from
    the priority queue. Has no effect when proof-of-work is disabled.
    If this is set to 0 there's no explicit limit and we will process
    requests as quickly as possible.
    (Default: 250)

[[HiddenServicePoWQueueBurst]] **HiddenServicePoWQueueBurst** __NUM__::

    The maximum burst size for rendezvous requests handled from the
    priority queue at once. (Default: 2500)

These options are applicable to both onion services and their clients:

[[CompiledProofOfWorkHash]] **CompiledProofOfWorkHash** **0**|**1**|**auto**::
    When proof-of-work DoS mitigation is active, both the services themselves
    and the clients which connect will use a dynamically generated hash
    function as part of the puzzle computation.
     +
    If this option is set to 1, puzzles will only be solved and verified using
    the compiled implementation (about 20x faster) and we choose to fail rather
    than using a slower fallback. If it's 0, the compiler will never be used.
    By default, the compiler is always tried if possible but the interpreter is
    available as a fallback. (Default: auto)

See also <<opt-list-modules,`--list-modules`>>, these proof of work options
have no effect unless the "`pow`" module is enabled at compile time.

== DIRECTORY AUTHORITY SERVER OPTIONS

The following options enable operation as a directory authority, and
control how Tor behaves as a directory authority.  You should not need
to adjust any of them if you're running a regular relay or exit server
on the public Tor network.

// Out of order because it logically belongs first in this section
[[AuthoritativeDirectory]] **AuthoritativeDirectory** **0**|**1**::
    When this option is set to 1, Tor operates as an authoritative directory
    server. Instead of caching the directory, it generates its own list of
    good servers, signs it, and sends that to the clients. Unless the clients
    already have you listed as a trusted directory, you probably do not want
    to set this option.

//Out of order because it belongs with the AuthoritativeDirectory option.
[[BridgeAuthoritativeDir]] **BridgeAuthoritativeDir** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor
    accepts and serves server descriptors, but it caches and serves the main
    networkstatus documents rather than generating its own. (Default: 0)

//Out of order because it belongs with the AuthoritativeDirectory option.
[[V3AuthoritativeDirectory]] **V3AuthoritativeDirectory** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor
    generates version 3 network statuses and serves descriptors, etc as
    described in dir-spec.txt file of https://spec.torproject.org/[torspec]
    (for Tor clients and servers running at least 0.2.0.x).

[[AuthDirBadExit]] **AuthDirBadExit** __AddressPattern...__::
    Authoritative directories only. A set of address patterns for servers that
    will be listed as bad exits in any network status document this authority
    publishes, if **AuthDirListBadExits** is set. +
     +
    (The address pattern syntax here and in the options below
    is the same as for exit policies, except that you don't need to say
    "accept" or "reject", and ports are not needed.)

[[AuthDirMiddleOnly]] **AuthDirMiddleOnly** __AddressPattern...__::
    Authoritative directories only. A set of address patterns for servers that
    will be listed as middle-only in any network status document this authority
    publishes, if **AuthDirListMiddleOnly** is set. +

[[AuthDirFastGuarantee]] **AuthDirFastGuarantee** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    Authoritative directories only. If non-zero, always vote the
    Fast flag for any relay advertising this amount of capacity or
    more. (Default: 100 KBytes)

[[AuthDirGuardBWGuarantee]] **AuthDirGuardBWGuarantee** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    Authoritative directories only. If non-zero, this advertised capacity
    or more is always sufficient to satisfy the bandwidth requirement
    for the Guard flag. (Default: 2 MBytes)

[[AuthDirHasIPv6Connectivity]] **AuthDirHasIPv6Connectivity** **0**|**1**::
    Authoritative directories only. When set to 0, OR ports with an
    IPv6 address are not included in the authority's votes. When set to 1,
    IPv6 OR ports are tested for reachability like IPv4 OR ports. If the
    reachability test succeeds, the authority votes for the IPv6 ORPort, and
    votes Running for the relay. If the reachability test fails, the authority
    does not vote for the IPv6 ORPort, and does not vote Running (Default: 0)  +
+
    The content of the consensus depends on the number of voting authorities
    that set AuthDirHasIPv6Connectivity:

      If no authorities set AuthDirHasIPv6Connectivity 1, there will be no
      IPv6 ORPorts in the consensus.

      If a minority of authorities set AuthDirHasIPv6Connectivity 1,
      unreachable IPv6 ORPorts will be removed from the consensus. But the
      majority of IPv4-only authorities will still vote the relay as Running.
      Reachable IPv6 ORPort lines will be included in the consensus

      If a majority of voting authorities set AuthDirHasIPv6Connectivity 1,
      relays with unreachable IPv6 ORPorts will not be listed as Running.
      Reachable IPv6 ORPort lines will be included in the consensus
      (To ensure that any valid majority will vote relays with unreachable
      IPv6 ORPorts not Running, 75% of authorities must set
      AuthDirHasIPv6Connectivity 1.)

[[AuthDirInvalid]] **AuthDirInvalid** __AddressPattern...__::
    Authoritative directories only. A set of address patterns for servers that
    will never be listed as "valid" in any network status document that this
    authority publishes.

[[AuthDirListBadExits]] **AuthDirListBadExits** **0**|**1**::
    Authoritative directories only. If set to 1, this directory has some
    opinion about which nodes are unsuitable as exit nodes. (Do not set this to
    1 unless you plan to list non-functioning exits as bad; otherwise, you are
    effectively voting in favor of every declared exit as an exit.)

[[AuthDirListMiddleOnly]] **AuthDirListMiddleOnly** **0**|**1**::
    Authoritative directories only. If set to 1, this directory has some
    opinion about which nodes should only be used in the middle position.
    (Do not set this to 1 unless you plan to list questionable relays
    as "middle only"; otherwise, you are effectively voting _against_
    middle-only status for every relay.)

[[AuthDirMaxServersPerAddr]] **AuthDirMaxServersPerAddr** __NUM__::
    Authoritative directories only. The maximum number of servers that we will
    list as acceptable on a single IP address. Set this to "0" for "no limit".
    (Default: 2)

[[AuthDirPinKeys]] **AuthDirPinKeys** **0**|**1**::
    Authoritative directories only. If non-zero, do not allow any relay to
    publish a descriptor if any other relay has reserved its <Ed25519,RSA>
    identity keypair. In all cases, Tor records every keypair it accepts
    in a journal if it is new, or if it differs from the most recently
    accepted pinning for one of the keys it contains. (Default: 1)

[[AuthDirReject]] **AuthDirReject** __AddressPattern__...::
    Authoritative directories only. A set of address patterns for servers that
    will never be listed at all in any network status document that this
    authority publishes, or accepted as an OR address in any descriptor
    submitted for publication by this authority.

[[AuthDirRejectRequestsUnderLoad]] **AuthDirRejectRequestsUnderLoad** **0**|**1**::
    If set, the directory authority will start rejecting directory requests
    from non relay connections by sending a 503 error code if it is under
    bandwidth pressure (reaching the configured limit if any). Relays will
    always tried to be answered even if this is on. (Default: 1)

//Out of order because it logically belongs with the other CCs options.
[[AuthDirBadExitCCs]] **AuthDirBadExitCCs** __CC__,... +

//Out of order because it logically belongs with the other CCs options.
[[AuthDirInvalidCCs]] **AuthDirInvalidCCs** __CC__,... +

//Out of order because it logically belongs with the other CCs options.
[[AuthDirMiddleOnlytCCs]] **AuthDirMiddleOnlyCCs** __CC__,... +

[[AuthDirRejectCCs]] **AuthDirRejectCCs** __CC__,...::
    Authoritative directories only. These options contain a comma-separated
    list of country codes such that any server in one of those country codes
    will be marked as a bad exit/invalid for use, or rejected
    entirely.

[[AuthDirSharedRandomness]] **AuthDirSharedRandomness** **0**|**1**::
    Authoritative directories only. Switch for the shared random protocol.
    If zero, the authority won't participate in the protocol. If non-zero
    (default), the flag "shared-rand-participate" is added to the authority
    vote indicating participation in the protocol. (Default: 1)

[[AuthDirTestEd25519LinkKeys]] **AuthDirTestEd25519LinkKeys**  **0**|**1**::
    Authoritative directories only. If this option is set to 0, then we treat
    relays as "Running" if their RSA key is correct when we probe them,
    regardless of their Ed25519 key. We should only ever set this option to 0
    if there is some major bug in Ed25519 link authentication that causes us
    to label all the relays as not Running.  (Default: 1)

[[AuthDirTestReachability]] **AuthDirTestReachability** **0**|**1**::
    Authoritative directories only. If set to 1, then we periodically
    check every relay we know about to see whether it is running.
    If set to 0, we vote Running for every relay, and don't perform
    these tests. (Default: 1)

[[AuthDirVoteGuard]] **AuthDirVoteGuard** __node__,__node__,__...__::
    A list of identity fingerprints or country codes or address patterns of
    nodes to vote Guard for regardless of their uptime and bandwidth. See
    <<ExcludeNodes,ExcludeNodes>> for more information on how to specify nodes.

[[AuthDirVoteGuardBwThresholdFraction]] **AuthDirVoteGuardBwThresholdFraction** __FRACTION__::
    The Guard flag bandwidth performance threshold fraction that is the
    fraction representing who gets the Guard flag out of all measured
    bandwidth. (Default: 0.75)

[[AuthDirVoteGuardGuaranteeTimeKnown]] **AuthDirVoteGuardGuaranteeTimeKnown** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    A relay with at least this much weighted time known can be considered
    familiar enough to be a guard. (Default: 8 days)

[[AuthDirVoteGuardGuaranteeWFU]] **AuthDirVoteGuardGuaranteeWFU** __FRACTION__::
    A level of weighted fractional uptime (WFU) is that is sufficient to be a
    Guard. (Default: 0.98)

[[AuthDirVoteStableGuaranteeMinUptime]] **AuthDirVoteStableGuaranteeMinUptime** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    If a relay's uptime is at least this value, then it is always considered
    stable, regardless of the rest of the network. (Default: 30 days)

[[AuthDirVoteStableGuaranteeMTBF]] **AuthDirVoteStableGuaranteeMTBF** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    If a relay's mean time between failures (MTBF) is least this value, then
    it will always be considered stable. (Default: 5 days)

[[BridgePassword]] **BridgePassword** __Password__::
    If set, contains an HTTP authenticator that tells a bridge authority to
    serve all requested bridge information. Used by the (only partially
    implemented) "bridge community" design, where a community of bridge
    relay operators all use an alternate bridge directory authority,
    and their target user audience can periodically fetch the list of
    available community bridges to stay up-to-date. (Default: not set)

[[ConsensusParams]] **ConsensusParams** __STRING__::
    STRING is a space-separated list of key=value pairs that Tor will include
    in the "params" line of its networkstatus vote. This directive can be
    specified multiple times so you don't have to put it all on one line.

[[DirAllowPrivateAddresses]] **DirAllowPrivateAddresses** **0**|**1**::
    If set to 1, Tor will accept server descriptors with arbitrary "Address"
    elements. Otherwise, if the address is not an IP address or is a private IP
    address, it will reject the server descriptor. Additionally, Tor
    will allow exit policies for private networks to fulfill Exit flag
    requirements. (Default: 0)

[[GuardfractionFile]] **GuardfractionFile** __FILENAME__::
    V3 authoritative directories only. Configures the location of the
    guardfraction file which contains information about how long relays
    have been guards. (Default: unset)

[[MinMeasuredBWsForAuthToIgnoreAdvertised]] **MinMeasuredBWsForAuthToIgnoreAdvertised** __N__::
    A total value, in abstract bandwidth units, describing how much
    measured total bandwidth an authority should have observed on the network
    before it will treat advertised bandwidths as wholly
    unreliable. (Default: 500)

[[MinUptimeHidServDirectoryV2]] **MinUptimeHidServDirectoryV2** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    Minimum uptime of a relay to be accepted as a hidden service directory
    by directory authorities. (Default: 96 hours)

[[RecommendedClientVersions]] **RecommendedClientVersions** __STRING__::
    STRING is a comma-separated list of Tor versions currently believed to be
    safe for clients to use. This information is included in version 2
    directories. If this is not set then the value of **RecommendedVersions**
    is used. When this is set then **VersioningAuthoritativeDirectory** should
    be set too.

[[RecommendedServerVersions]] **RecommendedServerVersions** __STRING__::
    STRING is a comma-separated list of Tor versions currently believed to be
    safe for servers to use. This information is included in version 2
    directories. If this is not set then the value of **RecommendedVersions**
    is used. When this is set then **VersioningAuthoritativeDirectory** should
    be set too.

[[RecommendedVersions]] **RecommendedVersions** __STRING__::
    STRING is a comma-separated list of Tor versions currently believed to be
    safe. The list is included in each directory, and nodes which pull down the
    directory learn whether they need to upgrade. This option can appear
    multiple times: the values from multiple lines are spliced together. When
    this is set then **VersioningAuthoritativeDirectory** should be set too.

[[MinimalAcceptedServerVersion]] **MinimalAcceptedServerVersion** __STRING__::
   STRING is the oldest Tor version accepted by the directory authority for
   relays and bridge. Any older version will be rejected.
   (Default: 0.4.7.0-alpha-dev)

[[V3AuthDistDelay]] **V3AuthDistDelay** __N__ **seconds**|**minutes**|**hours**::
    V3 authoritative directories only. Configures the server's preferred  delay
    between publishing its consensus and signature and assuming  it has all the
    signatures from all the other authorities. Note that the actual time used
    is not the server's preferred time,  but the consensus of all preferences.
    (Default: 5 minutes)

[[V3AuthNIntervalsValid]] **V3AuthNIntervalsValid** __NUM__::
    V3 authoritative directories only. Configures the number of VotingIntervals
    for which each consensus should be valid for. Choosing high numbers
    increases network partitioning risks; choosing low numbers increases
    directory traffic. Note that the actual number of intervals used is not the
    server's preferred number, but the consensus of all preferences. Must be at
    least 2. (Default: 3)

[[V3AuthUseLegacyKey]] **V3AuthUseLegacyKey** **0**|**1**::
    If set, the directory authority will sign consensuses not only with its
    own signing key, but also with a "legacy" key and certificate with a
    different identity.  This feature is used to migrate directory authority
    keys in the event of a compromise.  (Default: 0)

[[V3AuthVoteDelay]] **V3AuthVoteDelay** __N__ **seconds**|**minutes**|**hours**::
    V3 authoritative directories only. Configures the server's preferred delay
    between publishing its vote and assuming it has all the votes from all the
    other authorities. Note that the actual time used is not the server's
    preferred time, but the consensus of all preferences. (Default: 5
    minutes)

[[V3AuthVotingInterval]] **V3AuthVotingInterval** __N__ **minutes**|**hours**::
    V3 authoritative directories only. Configures the server's preferred voting
    interval. Note that voting will __actually__ happen at an interval chosen
    by consensus from all the authorities' preferred intervals. This time
    SHOULD divide evenly into a day. (Default: 1 hour)

[[V3BandwidthsFile]] **V3BandwidthsFile** __FILENAME__::
    V3 authoritative directories only. Configures the location of the
    bandwidth-authority generated file storing information on relays' measured
    bandwidth capacities. To avoid inconsistent reads, bandwidth data should
    be written to temporary file, then renamed to the configured filename.
    (Default: unset)

[[VersioningAuthoritativeDirectory]] **VersioningAuthoritativeDirectory** **0**|**1**::
    When this option is set to 1, Tor adds information on which versions of
    Tor are still believed safe for use to the published directory. Each
    version 1 authority is automatically a versioning authority; version 2
    authorities provide this service optionally. See <<RecommendedVersions,RecommendedVersions>>,
    <<RecommendedClientVersions,RecommendedClientVersions>>, and <<RecommendedServerVersions,RecommendedServerVersions>>.

== HIDDEN SERVICE OPTIONS

The following options are used to configure a hidden service. Some options
apply per service and some apply for the whole tor instance.

The next section describes the per service options that can only be set
**after** the **HiddenServiceDir** directive

**PER SERVICE OPTIONS:**

[[HiddenServiceAllowUnknownPorts]] **HiddenServiceAllowUnknownPorts** **0**|**1**::
   If set to 1, then connections to unrecognized ports do not cause the
   current hidden service to close rendezvous circuits. (Setting this to 0 is
   not an authorization mechanism; it is instead meant to be a mild
   inconvenience to port-scanners.) (Default: 0)

[[HiddenServiceDir]] **HiddenServiceDir** __DIRECTORY__::
    Store data files for a hidden service in DIRECTORY. Every hidden service
    must have a separate directory. You may use this option  multiple times to
    specify multiple services. If DIRECTORY does not exist, Tor will create it.
    Please note that you cannot add new Onion Service to already running Tor
    instance if **Sandbox** is enabled.
    (Note: in current versions of Tor, if DIRECTORY is a relative path,
    it will be relative to the current
    working directory of Tor instance, not to its DataDirectory.  Do not
    rely on this behavior; it is not guaranteed to remain the same in future
    versions.)

[[HiddenServiceDirGroupReadable]] **HiddenServiceDirGroupReadable** **0**|**1**::
    If this option is set to 1, allow the filesystem group to read the
    hidden service directory and hostname file. If the option is set to 0,
    only owner is able to read the hidden service directory. (Default: 0)
    Has no effect on Windows.

[[HiddenServiceExportCircuitID]] **HiddenServiceExportCircuitID** __protocol__::
   The onion service will use the given protocol to expose the global circuit
   identifier of each inbound client circuit. The only
   protocol supported right now \'haproxy'. This option is only for v3
   services. (Default: none) +
     +
   The haproxy option works in the following way: when the feature is
   enabled, the Tor process will write a header line when a client is connecting
   to the onion service. The header will look like this: +
     +
   "PROXY TCP6 fc00:dead:beef:4dad::ffff:ffff ::1 65535 42\r\n" +
     +
   We encode the "global circuit identifier" as the last 32-bits of the first
   IPv6 address. All other values in the header can safely be ignored. You can
   compute the global circuit identifier using the following formula given the
   IPv6 address "fc00:dead:beef:4dad::AABB:CCDD": +
     +
      global_circuit_id = (0xAA << 24) + (0xBB << 16) + (0xCC << 8) + 0xDD; +
     +
   In the case above, where the last 32-bits are 0xffffffff, the global circuit
   identifier would be 4294967295. You can use this value together with Tor's
   control port to terminate particular circuits using their global
   circuit identifiers. For more information about this see control-spec.txt. +
     +
   The HAProxy version 1 protocol is described in detail at
   https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

[[HiddenServiceOnionBalanceInstance]] **HiddenServiceOnionBalanceInstance** **0**|**1**::

   If set to 1, this onion service becomes an OnionBalance instance and will
   accept client connections destined to an OnionBalance frontend. In this
   case, Tor expects to find a file named "ob_config" inside the
   **HiddenServiceDir** directory with content:
     +
      MasterOnionAddress <frontend_onion_address>
     +
   where <frontend_onion_address> is the onion address of the OnionBalance
   frontend (e.g. wrxdvcaqpuzakbfww5sxs6r2uybczwijzfn2ezy2osaj7iox7kl7nhad.onion).


[[HiddenServiceMaxStreams]] **HiddenServiceMaxStreams** __N__::
   The maximum number of simultaneous streams (connections) per rendezvous
   circuit. The maximum value allowed is 65535. (Setting this to 0 will allow
   an unlimited number of simultaneous streams.) (Default: 0)

[[HiddenServiceMaxStreamsCloseCircuit]] **HiddenServiceMaxStreamsCloseCircuit** **0**|**1**::
   If set to 1, then exceeding **HiddenServiceMaxStreams** will cause the
   offending rendezvous circuit to be torn down, as opposed to stream creation
   requests that exceed the limit being silently ignored. (Default: 0)

[[HiddenServiceNumIntroductionPoints]] **HiddenServiceNumIntroductionPoints** __NUM__::
    Number of introduction points the hidden service will have. You can't
    have more than 20. (Default: 3)

[[HiddenServicePort]] **HiddenServicePort** __VIRTPORT__ [__TARGET__]::
    Configure a virtual port VIRTPORT for a hidden service. You may use this
    option multiple times; each time applies to the service using the most
    recent HiddenServiceDir. By default, this option maps the virtual port to
    the same port on 127.0.0.1 over TCP. You may override the target port,
    address, or both by specifying a target of addr, port, addr:port, or
    **unix:**__path__.  (You can specify an IPv6 target as [addr]:port. Unix
    paths may be quoted, and may use standard C escapes.)
    You may also have multiple lines with  the same VIRTPORT: when a user
    connects to that VIRTPORT, one of the TARGETs from those lines will be
    chosen at random. Note that address-port pairs have to be comma-separated.

[[HiddenServiceVersion]] **HiddenServiceVersion** **3**::
    A list of rendezvous service descriptor versions to publish for the hidden
    service. Currently, only version 3 is supported. (Default: 3)


**PER INSTANCE OPTIONS:**

[[HiddenServiceSingleHopMode]] **HiddenServiceSingleHopMode** **0**|**1**::
    **Experimental - Non Anonymous** Hidden Services on a tor instance in
    HiddenServiceSingleHopMode make one-hop (direct) circuits between the onion
    service server, and the introduction and rendezvous points. (Onion service
    descriptors are still posted using 3-hop paths, to avoid onion service
    directories blocking the service.)
    This option makes every hidden service instance hosted by a tor instance a
    Single Onion Service. One-hop circuits make Single Onion servers easily
    locatable, but clients remain location-anonymous. However, the fact that a
    client is accessing a Single Onion rather than a Hidden Service may be
    statistically distinguishable. +
     +
    **WARNING:** Once a hidden service directory has been used by a tor
    instance in HiddenServiceSingleHopMode, it can **NEVER** be used again for
    a hidden service. It is best practice to create a new hidden service
    directory, key, and address for each new Single Onion Service and Hidden
    Service. It is not possible to run Single Onion Services and Hidden
    Services from the same tor instance: they should be run on different
    servers with different IP addresses. +
     +
    HiddenServiceSingleHopMode requires HiddenServiceNonAnonymousMode to be set
    to 1. Since a Single Onion service is non-anonymous, you can not configure
    a SOCKSPort on a tor instance that is running in
    **HiddenServiceSingleHopMode**. Can not be changed while tor is running.
    (Default: 0)

//Out of order because it belongs after HiddenServiceSingleHopMode.
[[HiddenServiceNonAnonymousMode]] **HiddenServiceNonAnonymousMode** **0**|**1**::
    Makes hidden services non-anonymous on this tor instance. Allows the
    non-anonymous HiddenServiceSingleHopMode. Enables direct connections in the
    server-side hidden service protocol.  If you are using this option,
    you need to disable all client-side services on your Tor instance,
    including setting SOCKSPort to "0". Can not be changed while tor is
    running. (Default: 0)

[[PublishHidServDescriptors]] **PublishHidServDescriptors** **0**|**1**::
    If set to 0, Tor will run any hidden services you configure, but it won't
    advertise them to the rendezvous directory. This option is only useful if
    you're using a Tor controller that handles hidserv publishing for you.
    (Default: 1)

[[client-authorization]]
== CLIENT AUTHORIZATION

Service side:

  To configure client authorization on the service side, the
  "<HiddenServiceDir>/authorized_clients/" directory needs to exist. Each file
  in that directory should be suffixed with ".auth" (i.e. "alice.auth"; the
  file name is irrelevant) and its content format MUST be:

          <auth-type>:<key-type>:<base32-encoded-public-key>

  The supported <auth-type> are: "descriptor". The supported <key-type> are:
  "x25519". The <base32-encoded-public-key> is the base32 representation of
  the raw key bytes only (32 bytes for x25519).

  Each file MUST contain one line only. Any malformed file will be
  ignored. Client authorization will only be enabled for the service if tor
  successfully loads at least one authorization file.

  Note that once you've configured client authorization, anyone else with the
  address won't be able to access it from this point on. If no authorization is
  configured, the service will be accessible to anyone with the onion address.

  Revoking a client can be done by removing their ".auth" file, however the
  revocation will be in effect only after the tor process gets restarted or if
  a SIGHUP takes place.

Client side:

  To access a v3 onion service with client authorization as a client, make sure
  you have ClientOnionAuthDir set in your torrc. Then, in the
  <ClientOnionAuthDir> directory, create an .auth_private file for the onion
  service corresponding to this key (i.e. 'bob_onion.auth_private').  The
  contents of the <ClientOnionAuthDir>/<user>.auth_private file should look like:

      <56-char-onion-addr-without-.onion-part>:descriptor:x25519:<x25519 private key in base32>

For more information, please see https://2019.www.torproject.org/docs/tor-onion-service.html.en#ClientAuthorization .

== TESTING NETWORK OPTIONS

The following options are used for running a testing Tor network.

//Out of order because it logically belongs first in this section.
[[TestingTorNetwork]] **TestingTorNetwork** **0**|**1**::
    If set to 1, Tor adjusts default values of the configuration options below,
    so that it is easier to set up a testing Tor network. May only be set if
    non-default set of DirAuthorities is set. Cannot be unset while Tor is
    running.
    (Default: 0) +

       DirAllowPrivateAddresses 1
       EnforceDistinctSubnets 0
       AuthDirMaxServersPerAddr 0
       ClientBootstrapConsensusAuthorityDownloadInitialDelay 0
       ClientBootstrapConsensusFallbackDownloadInitialDelay 0
       ClientBootstrapConsensusAuthorityOnlyDownloadInitialDelay 0
       ClientDNSRejectInternalAddresses 0
       ClientRejectInternalAddresses 0
       CountPrivateBandwidth 1
       ExitPolicyRejectPrivate 0
       ExtendAllowPrivateAddresses 1
       V3AuthVotingInterval 5 minutes
       V3AuthVoteDelay 20 seconds
       V3AuthDistDelay 20 seconds
       TestingV3AuthInitialVotingInterval 150 seconds
       TestingV3AuthInitialVoteDelay 20 seconds
       TestingV3AuthInitialDistDelay 20 seconds
       TestingAuthDirTimeToLearnReachability 0 minutes
       MinUptimeHidServDirectoryV2 0 minutes
       TestingServerDownloadInitialDelay 0
       TestingClientDownloadInitialDelay 0
       TestingServerConsensusDownloadInitialDelay 0
       TestingClientConsensusDownloadInitialDelay 0
       TestingBridgeDownloadInitialDelay 10
       TestingBridgeBootstrapDownloadInitialDelay 0
       TestingClientMaxIntervalWithoutRequest 5 seconds
       TestingDirConnectionMaxStall 30 seconds
       TestingEnableConnBwEvent 1
       TestingEnableCellStatsEvent 1

[[TestingAuthDirTimeToLearnReachability]] **TestingAuthDirTimeToLearnReachability** __N__ **seconds**|**minutes**|**hours**::
    After starting as an authority, do not make claims about whether routers
    are Running until this much time has passed. Changing this requires
    that **TestingTorNetwork** is set.  (Default: 30 minutes)

[[TestingAuthKeyLifetime]] **TestingAuthKeyLifetime** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**|**months**::
    Overrides the default lifetime for a signing Ed25519 TLS Link authentication
    key.
    (Default: 2 days)

[[TestingAuthKeySlop]] **TestingAuthKeySlop** __N__ **seconds**|**minutes**|**hours** +

[[TestingBridgeBootstrapDownloadInitialDelay]] **TestingBridgeBootstrapDownloadInitialDelay** __N__::
    Initial delay in seconds for how long clients should wait before
    downloading a bridge descriptor for a new bridge.
    Changing this requires that **TestingTorNetwork** is set. (Default: 0)

[[TestingBridgeDownloadInitialDelay]] **TestingBridgeDownloadInitialDelay** __N__::
    How long to wait (in seconds) once clients have successfully
    downloaded a bridge descriptor, before trying another download for
    that same bridge. Changing this requires that **TestingTorNetwork**
    is set. (Default: 10800)

[[TestingClientConsensusDownloadInitialDelay]] **TestingClientConsensusDownloadInitialDelay** __N__::
    Initial delay in seconds for when clients should download consensuses. Changing this
    requires that **TestingTorNetwork** is set. (Default: 0)

[[TestingClientDownloadInitialDelay]] **TestingClientDownloadInitialDelay** __N__::
    Initial delay in seconds for when clients should download things in general. Changing this
    requires that **TestingTorNetwork** is set. (Default: 0)

[[TestingClientMaxIntervalWithoutRequest]] **TestingClientMaxIntervalWithoutRequest** __N__ **seconds**|**minutes**::
    When directory clients have only a few descriptors to request, they batch
    them until they have more, or until this amount of time has passed.
    Changing this requires that **TestingTorNetwork** is set. (Default: 10
    minutes)

[[TestingDirAuthVoteExit]] **TestingDirAuthVoteExit** __node__,__node__,__...__::
    A list of identity fingerprints, country codes, and
    address patterns of nodes to vote Exit for regardless of their
    uptime, bandwidth, or exit policy. See <<ExcludeNodes,ExcludeNodes>>
     for more information on how to specify nodes. +
     +
    In order for this option to have any effect, **TestingTorNetwork**
    has to be set. See <<ExcludeNodes,ExcludeNodes>> for more
    information on how to specify nodes.

[[TestingDirAuthVoteExitIsStrict]] **TestingDirAuthVoteExitIsStrict** **0**|**1** ::
    If True (1), a node will never receive the Exit flag unless it is specified
    in the **TestingDirAuthVoteExit** list, regardless of its uptime, bandwidth,
    or exit policy. +
     +
    In order for this option to have any effect, **TestingTorNetwork**
    has to be set.

[[TestingDirAuthVoteGuard]] **TestingDirAuthVoteGuard** __node__,__node__,__...__::
    A list of identity fingerprints and country codes and
    address patterns of nodes to vote Guard for regardless of their
    uptime and bandwidth. See <<ExcludeNodes,ExcludeNodes>> for more
    information on how to specify nodes. +
     +
    In order for this option to have any effect, **TestingTorNetwork**
    has to be set.

[[TestingDirAuthVoteGuardIsStrict]] **TestingDirAuthVoteGuardIsStrict** **0**|**1** ::
    If True (1), a node will never receive the Guard flag unless it is specified
    in the **TestingDirAuthVoteGuard** list, regardless of its uptime and bandwidth. +
     +
    In order for this option to have any effect, **TestingTorNetwork**
    has to be set.

[[TestingDirAuthVoteHSDir]] **TestingDirAuthVoteHSDir** __node__,__node__,__...__::
    A list of identity fingerprints and country codes and
    address patterns of nodes to vote HSDir for regardless of their
    uptime and DirPort. See <<ExcludeNodes,ExcludeNodes>> for more
    information on how to specify nodes. +
     +
    In order for this option to have any effect, **TestingTorNetwork**
    must be set.

[[TestingDirAuthVoteHSDirIsStrict]] **TestingDirAuthVoteHSDirIsStrict** **0**|**1** ::
    If True (1), a node will never receive the HSDir flag unless it is specified
    in the **TestingDirAuthVoteHSDir** list, regardless of its uptime and DirPort. +
     +
    In order for this option to have any effect, **TestingTorNetwork**
    has to be set.

[[TestingDirConnectionMaxStall]] **TestingDirConnectionMaxStall** __N__ **seconds**|**minutes**::
    Let a directory connection stall this long before expiring it.
    Changing this requires that **TestingTorNetwork** is set. (Default:
    5 minutes)

[[TestingEnableCellStatsEvent]] **TestingEnableCellStatsEvent** **0**|**1**::
    If this option is set, then Tor controllers may register for CELL_STATS
    events.  Changing this requires that **TestingTorNetwork** is set.
    (Default: 0)

[[TestingEnableConnBwEvent]] **TestingEnableConnBwEvent** **0**|**1**::
    If this option is set, then Tor controllers may register for CONN_BW
    events.  Changing this requires that **TestingTorNetwork** is set.
    (Default: 0)

[[TestingLinkCertLifetime]] **TestingLinkCertLifetime** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**|**months**::
    Overrides the default lifetime for the certificates used to authenticate
    our X509 link cert with our ed25519 signing key.
    (Default: 2 days)

[[TestingLinkKeySlop]] **TestingLinkKeySlop** __N__ **seconds**|**minutes**|**hours** +

[[TestingMinExitFlagThreshold]] **TestingMinExitFlagThreshold**  __N__ **KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    Sets a lower-bound for assigning an exit flag when running as an
    authority on a testing network. Overrides the usual default lower bound
    of 4 KBytes. (Default: 0)

[[TestingMinFastFlagThreshold]] **TestingMinFastFlagThreshold** __N__ **bytes**|**KBytes**|**MBytes**|**GBytes**|**TBytes**|**KBits**|**MBits**|**GBits**|**TBits**::
    Minimum value for the Fast flag.  Overrides the ordinary minimum taken
    from the consensus when TestingTorNetwork is set. (Default: 0.)

[[TestingMinTimeToReportBandwidth]] **TestingMinTimeToReportBandwidth** __N__ **seconds**|**minutes**|**hours**::
    Do not report our measurements for our maximum observed bandwidth for any
    time period that has lasted for less than this amount of time.
    Values over 1 day have no effect. (Default: 1 day)

[[TestingServerConsensusDownloadInitialDelay]] **TestingServerConsensusDownloadInitialDelay** __N__::
    Initial delay in seconds for when servers should download consensuses. Changing this
    requires that **TestingTorNetwork** is set. (Default: 0)

[[TestingServerDownloadInitialDelay]] **TestingServerDownloadInitialDelay** __N__::
    Initial delay in seconds for when servers should download things in general. Changing this
    requires that **TestingTorNetwork** is set. (Default: 0)

[[TestingSigningKeySlop]] **TestingSigningKeySlop** __N__ **seconds**|**minutes**|**hours**::
    How early before the official expiration of a an Ed25519 signing key do
    we replace it and issue a new key?
    (Default: 3 hours for link and auth; 1 day for signing.)

[[TestingV3AuthInitialDistDelay]] **TestingV3AuthInitialDistDelay** __N__ **seconds**|**minutes**|**hours**::
    Like V3AuthDistDelay, but for initial voting interval before
    the first consensus has been created. Changing this requires that
    **TestingTorNetwork** is set. (Default: 5 minutes)

[[TestingV3AuthInitialVoteDelay]] **TestingV3AuthInitialVoteDelay** __N__ **seconds**|**minutes**|**hours**::
    Like V3AuthVoteDelay, but for initial voting interval before
    the first consensus has been created. Changing this requires that
    **TestingTorNetwork** is set. (Default: 5 minutes)

[[TestingV3AuthInitialVotingInterval]] **TestingV3AuthInitialVotingInterval** __N__ **seconds**|**minutes**|**hours**::
    Like V3AuthVotingInterval, but for initial voting interval before the first
    consensus has been created. Changing this requires that
    **TestingTorNetwork** is set. (Default: 30 minutes)

[[TestingV3AuthVotingStartOffset]] **TestingV3AuthVotingStartOffset** __N__ **seconds**|**minutes**|**hours**::
    Directory authorities offset voting start time by this much.
    Changing this requires that **TestingTorNetwork** is set. (Default: 0)


== NON-PERSISTENT OPTIONS

These options are not saved to the torrc file by the "SAVECONF" controller
command.  Other options of this type are documented in control-spec.txt,
section 5.4. End-users should mostly ignore them.

[[UnderscorePorts]] **{dbl_}ControlPort**, **{dbl_}DirPort**, **{dbl_}DNSPort**, **{dbl_}ExtORPort**, **{dbl_}NATDPort**, **{dbl_}ORPort**, **{dbl_}SocksPort**, **{dbl_}TransPort**::
    These underscore-prefixed options are variants of the regular Port
    options.  They behave the same, except they are not saved to the
    torrc file by the controller's SAVECONF command.


== SIGNALS

Tor catches the following signals:

[[SIGTERM]] **SIGTERM**::
    Tor will catch this, clean up and sync to disk if necessary, and exit.

[[SIGINT]] **SIGINT**::
    Tor clients behave as with SIGTERM; but Tor servers will do a controlled
    slow shutdown, closing listeners and waiting 30 seconds before exiting.
    (The delay can be configured with the ShutdownWaitLength config option.)

[[SIGHUP]] **SIGHUP**::
    The signal instructs Tor to reload its configuration (including closing and
    reopening logs), and kill and restart its helper processes if applicable.

[[SIGUSR1]] **SIGUSR1**::
    Log statistics about current connections, past connections, and throughput.

[[SIGUSR2]] **SIGUSR2**::
    Switch all logs to loglevel debug. You can go back to the old loglevels by
    sending a SIGHUP.

[[SIGCHLD]] **SIGCHLD**::
    Tor receives this signal when one of its helper processes has exited, so it
    can clean up.

[[SIGPIPE]] **SIGPIPE**::
    Tor catches this signal and ignores it.

[[SIGXFSZ]] **SIGXFSZ**::
    If this signal exists on your platform, Tor catches and ignores it.

== FILES

**`@CONFDIR@/torrc`**::
    Default location of the configuration file.

**`$HOME/.torrc`**::
    Fallback location for torrc, if @CONFDIR@/torrc is not found.

**`@LOCALSTATEDIR@/lib/tor/`**::
    The tor process stores keys and other data here.

__CacheDirectory__/**`cached-certs`**::
    Contains downloaded directory key certificates that are used to verify
    authenticity of documents generated by the Tor directory authorities.

__CacheDirectory__/**`cached-consensus`** and/or **`cached-microdesc-consensus`**::
    The most recent consensus network status document we've downloaded.

__CacheDirectory__/**`cached-descriptors`** and **`cached-descriptors.new`**::
    These files contain the downloaded router statuses. Some routers may appear
    more than once; if so, the most recently published descriptor is
    used. Lines beginning with **`@`**-signs are annotations that contain more
    information about a given router. The **`.new`** file is an append-only
    journal; when it gets too large, all entries are merged into a new
    cached-descriptors file.

__CacheDirectory__/**`cached-extrainfo`** and **`cached-extrainfo.new`**::
    Similar to **cached-descriptors**, but holds optionally-downloaded
    "extra-info" documents. Relays use these documents to send inessential
    information about statistics, bandwidth history, and network health to the
    authorities. They aren't fetched by default. See <<DownloadExtraInfo,DownloadExtraInfo>>
     for more information.

__CacheDirectory__/**`cached-microdescs`** and **`cached-microdescs.new`**::
    These files hold downloaded microdescriptors.  Lines beginning with
    **`@`**-signs are annotations that contain more information about a given
    router. The **`.new`** file is an append-only journal; when it gets too
    large, all entries are merged into a new cached-microdescs file.

__DataDirectory__/**`state`**::
    Contains a set of persistent key-value mappings. These include:
        - the current entry guards and their status.
        - the current bandwidth accounting values.
        - when the file was last written
        - what version of Tor generated the state file
        - a short history of bandwidth usage, as produced in the server
          descriptors.

__DataDirectory__/**`sr-state`**::
    _Authority only_. This file is used to record information about the current
    status of the shared-random-value voting state.

__CacheDirectory__/**`diff-cache`**::
    _Directory cache only_. Holds older consensuses and diffs from oldest to
    the most recent consensus of each type compressed in various ways. Each
    file contains a set of key-value arguments describing its contents,
    followed by a single NUL byte, followed by the main file contents.

__DataDirectory__/**`bw_accounting`**::
    This file is obsolete and the data is now stored in the **`state`** file
    instead. Used to track bandwidth accounting values (when the current period
    starts and ends; how much has been read and written so far this period).

__DataDirectory__/**`control_auth_cookie`**::
    This file can be used only when cookie authentication is enabled. Used for
    cookie authentication with the controller. Location can be overridden by
    the `CookieAuthFile` configuration option. Regenerated on startup. See
    control-spec.txt in https://spec.torproject.org/[torspec] for details.

__DataDirectory__/**`lock`**::
    This file is used to prevent two Tor instances from using the same data
    directory. If access to this file is locked, data directory is already in
    use by Tor.

__DataDirectory__/**`key-pinning-journal`**::
    Used by authorities. A line-based file that records mappings between
    RSA1024 and Ed25519 identity keys. Authorities enforce these mappings, so
    that once a relay has picked an Ed25519 key, stealing or factoring the
    RSA1024 key will no longer let an attacker impersonate the relay.

__KeyDirectory__/**`authority_identity_key`**::
    A v3 directory authority's master identity key, used to authenticate its
    signing key. Tor doesn't use this while it's running. The tor-gencert
    program uses this. If you're running an authority, you should keep this key
    offline, and not put it in this file.

__KeyDirectory__/**`authority_certificate`**::
    Only directory authorities use this file. A v3 directory authority's
    certificate which authenticates the authority's current vote- and
    consensus-signing key using its master identity key.

__KeyDirectory__/**`authority_signing_key`**::
    Only directory authorities use this file. A v3 directory authority's
    signing key that is used to sign votes and consensuses. Corresponds to the
    **authority_certificate** cert.

__KeyDirectory__/**`legacy_certificate`**::
    As authority_certificate; used only when `V3AuthUseLegacyKey` is set.  See
    documentation for <<V3AuthUseLegacyKey,V3AuthUseLegacyKey>>.

__KeyDirectory__/**`legacy_signing_key`**::
    As authority_signing_key: used only when `V3AuthUseLegacyKey` is set.  See
    documentation for <<V3AuthUseLegacyKey,V3AuthUseLegacyKey>>.

__KeyDirectory__/**`secret_id_key`**::
    A relay's RSA1024 permanent identity key, including private and public
    components. Used to sign router descriptors, and to sign other keys.

__KeyDirectory__/**`ed25519_master_id_public_key`**::
    The public part of a relay's Ed25519 permanent identity key.

__KeyDirectory__/**`ed25519_master_id_secret_key`**::
    The private part of a relay's Ed25519 permanent identity key.  This key is
    used to sign the medium-term ed25519 signing key.  This file can be kept
    offline or encrypted. If so, Tor will not be able to generate new signing
    keys automatically; you'll need to use `tor --keygen` to do so.

__KeyDirectory__/**`ed25519_signing_secret_key`**::
    The private and public components of a relay's medium-term Ed25519 signing
    key. This key is authenticated by the Ed25519 master key, which in turn
    authenticates other keys (and router descriptors).

__KeyDirectory__/**`ed25519_signing_cert`**::
    The certificate which authenticates "ed25519_signing_secret_key" as having
    been signed by the Ed25519 master key.

__KeyDirectory__/**`secret_onion_key`** and **`secret_onion_key.old`**::
    A relay's RSA1024 short-term onion key. Used to decrypt old-style ("TAP")
    circuit extension requests. The **`.old`** file holds the previously
    generated key, which the relay uses to handle any requests that were made
    by clients that didn't have the new one.

__KeyDirectory__/**`secret_onion_key_ntor`** and **`secret_onion_key_ntor.old`**::
    A relay's Curve25519 short-term onion key. Used to handle modern ("ntor")
    circuit extension requests. The **`.old`** file holds the previously
    generated key, which the relay uses to handle any requests that were made
    by clients that didn't have the new one.

__DataDirectory__/**`fingerprint`**::
    Only used by servers. Contains the fingerprint of the server's RSA
    identity key.

__DataDirectory__/**`fingerprint-ed25519`**::
    Only used by servers. Contains the fingerprint of the server's ed25519
    identity key.

__DataDirectory__/**`hashed-fingerprint`**::
    Only used by bridges. Contains the hashed fingerprint of the bridge's
    identity key. (That is, the hash of the hash of the identity key.)

__DataDirectory__/**`approved-routers`**::
    Only used by authoritative directory servers. Each line lists a status and
    an identity, separated by whitespace. Identities can be hex-encoded RSA
    fingerprints, or base-64 encoded ed25519 public keys. See the
    **fingerprint** file in a tor relay's __DataDirectory__ for an example
    fingerprint line. If the status is **!reject**, then descriptors from the
    given identity are rejected by this server. If it is **!invalid** then
    descriptors are accepted, but marked in the vote as not valid.
    If it is **!badexit**, then the authority will vote for it to receive a
    BadExit flag, indicating that it shouldn't be used for traffic leaving
    the Tor network.  If it is **!middleonly**, then the authority will
    vote for it to only be used in the middle of circuits.
    (Neither rejected nor invalid relays are included in the consensus.)

__DataDirectory__/**`v3-status-votes`**::
    Only for v3 authoritative directory servers. This file contains status
    votes from all the authoritative directory servers.

__CacheDirectory__/**`unverified-consensus`**::
    Contains a network consensus document that has been downloaded, but which
    we didn't have the right certificates to check yet.

__CacheDirectory__/**`unverified-microdesc-consensus`**::
    Contains a microdescriptor-flavored network consensus document that has
    been downloaded, but which we didn't have the right certificates to check
    yet.

__DataDirectory__/**`unparseable-desc`**::
    Onion server descriptors that Tor was unable to parse are dumped to this
    file. Only used for debugging.

__DataDirectory__/**`router-stability`**::
    Only used by authoritative directory servers. Tracks measurements for
    router mean-time-between-failures so that authorities have a fair idea of
    how to set their Stable flags.

__DataDirectory__/**`stats/dirreq-stats`**::
    Only used by directory caches and authorities. This file is used to
    collect directory request statistics.

__DataDirectory__/**`stats/entry-stats`**::
    Only used by servers. This file is used to collect incoming connection
    statistics by Tor entry nodes.

__DataDirectory__/**`stats/bridge-stats`**::
    Only used by servers. This file is used to collect incoming connection
    statistics by Tor bridges.

__DataDirectory__/**`stats/exit-stats`**::
    Only used by servers. This file is used to collect outgoing connection
    statistics by Tor exit routers.

__DataDirectory__/**`stats/buffer-stats`**::
    Only used by servers. This file is used to collect buffer usage
    history.

__DataDirectory__/**`stats/conn-stats`**::
    Only used by servers. This file is used to collect approximate connection
    history (number of active connections over time).

__DataDirectory__/**`stats/hidserv-stats`**::
    Only used by servers. This file is used to collect approximate counts
    of what fraction of the traffic is hidden service rendezvous traffic, and
    approximately how many hidden services the relay has seen.

__DataDirectory__/**`networkstatus-bridges`**::
    Only used by authoritative bridge directories. Contains information
    about bridges that have self-reported themselves to the bridge
    authority.

__HiddenServiceDirectory__/**`hostname`**::
    The <base32-encoded-fingerprint>.onion domain name for this hidden service.
    If the hidden service is restricted to authorized clients only, this file
    also contains authorization data for all clients.
+
[NOTE]
    The clients will ignore any extra subdomains prepended to a hidden
    service hostname. Supposing you have "xyz.onion" as your hostname, you
    can ask your clients to connect to "www.xyz.onion" or "irc.xyz.onion"
    for virtual-hosting purposes.

__HiddenServiceDirectory__/**`private_key`**::
    Contains the private key for this hidden service.

__HiddenServiceDirectory__/**`client_keys`**::
    Contains authorization data for a hidden service that is only accessible by
    authorized clients.

__HiddenServiceDirectory__/**`onion_service_non_anonymous`**::
    This file is present if a hidden service key was created in
    **HiddenServiceNonAnonymousMode**.

== SEE ALSO

For more information, refer to the Tor Project website at
https://www.torproject.org/ and the Tor specifications at
https://spec.torproject.org. See also **torsocks**(1) and **torify**(1).

== BUGS

Because Tor is still under development, there may be plenty of bugs. Please
report them at https://bugs.torproject.org/.