man/nbd-server.1.in.sgml

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  11
  12   <!-- Fill in your name for FIRSTNAME and SURNAME. -->
  13   <!ENTITY dhfirstname "<firstname>Wouter</firstname>">
  14   <!ENTITY dhsurname   "<surname>Verhelst</surname>">
  15   <!-- Please adjust the date whenever revising the manpage. -->
  16   <!ENTITY dhdate      "<date>$Date$</date>">
  17   <!-- SECTION should be 1-8, maybe w/ subsection other parameters are
  18        allowed: see man(7), man(1). -->
  19   <!ENTITY dhsection   "<manvolnum>1</manvolnum>">
  20   <!ENTITY dhemail     "<email>wouter@debian.org</email>">
  21   <!ENTITY dhusername  "Wouter Verhelst">
  22   <!ENTITY dhucpackage "<refentrytitle>NBD-SERVER</refentrytitle>">
  23   <!ENTITY dhpackage   "nbd-server">
  24
  25   <!ENTITY debian      "<productname>Debian GNU/Linux</productname>">
  26   <!ENTITY gnu         "<acronym>GNU</acronym>">
  27 ]>
  28
  29 <refentry>
  30   <refentryinfo>
  31     <address>
  32       &dhemail;
  33     </address>
  34     <author>
  35       &dhfirstname;
  36       &dhsurname;
  37     </author>
  38     <copyright>
  39       <year>2001</year>
  40       <holder>&dhusername;</holder>
  41     </copyright>
  42     &dhdate;
  43   </refentryinfo>
  44   <refmeta>
  45     &dhucpackage;
  46
  47     &dhsection;
  48   </refmeta>
  49   <refnamediv>
  50     <refname>&dhpackage;</refname>
  51
  52     <refpurpose>serve a file as a block device to other computers
  53     running the &gnu;/Linux(tm) or &gnu;/Hurd Operating
  54     System</refpurpose>
  55   </refnamediv>
  56   <refsynopsisdiv>
  57     <cmdsynopsis>
  58       <command>&dhpackage; </command>
  59
  60       <arg choice=plain><replaceable>[ip@]port</replaceable</arg>
  61       <arg choice=plain><replaceable>filename</replaceable></arg>
  62       <arg><replaceable>size</replaceable></arg>
  63       <arg><option>-r</option></arg>
  64       <arg><option>-m</option></arg>
  65       <arg><option>-c</option></arg>
  66       <arg><option>-l <replaceable>host list filename</replaceable></option></arg>
  67       <arg><option>-o <replaceable>section name</replaceable></option></arg>
  68       <arg><option>-C <replaceable>config file</replaceable></option></arg>
  69       <arg><option>-M <replaceable>max connections</replaceable></option></arg>
  70       <arg><option>-d</option></arg>
  71     </cmdsynopsis>
  72   </refsynopsisdiv>
  73   <refsect1>
  74     <title>DESCRIPTION</title>
  75
  76     <para><command>&dhpackage;</command> is the server for the Linux
  77     Network Block Device (NBD). With NBD, a client can use a file,
  78     exported over the network from a server, as a block device. It can
  79     then be used for whatever purpose a normal block device (harddisk,
  80     CD-ROM, ...) can be used for.</para>
  81
  82     <para>NBD can be useful for diskless clients that need swapspace,
  83     but you can also create a filesystem on it and use it as though it
  84     were a local filesystem.</para>
  85
  86     <para><command>&dhpackage;</command> implements some security
  87     through a file called "$sysconfdir/nbd-server/allow" (by default; a
  88     different file can be chosen with the '-l' option or through a
  89     config file specification). This file must list the IP-addresses or
  90     network masks of clients that are allowed to connect. If it does not
  91     exist, all clients are able to connect. If the file is empty, no
  92     clients can connect.</para>
  93
  94     <para>Note that while the command line allows for specifying an
  95     export, the use of this option is deprecated. It is preferred to
  96     make use of a configuration file instead, the format of which is
  97     defined in nbd-server(5).</para>
  98   </refsect1>
  99   <refsect1>
 100     <title>OPTIONS</title>
 101
 102     <variablelist>
 103       <varlistentry>
 104         <term>ip</term>
 105         <listitem>
 106           <para>The ip address the server should listen on. This may
 107           be an IPv4 address, an IPv6 address, or a hostname. In the
 108           latter case, nbd-server will do a hostname lookup for the
 109           name specified, and will listen on the first address that is
 110           returned. For compatibility with past versions of
 111           nbd-server, if an IPv4 address is specified, the @ sign that
 112           serves as separator between the address and port may be
 113           replaced by a colon.</para>
 114           <para>If this parameter is not specified, nbd-server will
 115           listen on all local addresses on both IPv4 and IPv6. To
 116           limit to IPv4, specify the address as 0.0.0.0; to limit to
 117           IPv6, specify it as ::.</para>
 118         </listitem>
 119       </varlistentry>
 120       <varlistentry>
 121         <term><option>port</option>
 122         </term>
 123         <listitem>
 124           <para>The port the server should listen to. A valid port is
 125             any number between 1 and 65536; if 0 is used, nbd-server
 126             will listen on stdin (so that nbd-server can be ran from
 127             inetd)</para>
 128         </listitem>
 129       </varlistentry>
 130       <varlistentry>
 131         <term><option>filename</option></term>
 132         <listitem>
 133           <para>The filename of the file that should be exported. This
 134           can be any file, including "real" blockdevices (i.e. a file
 135           from /dev). If the filename includes the literal string
 136           "%s", then this %s will be substituded with the IP-address
 137           of the client trying to connect.</para>
 138         </listitem>
 139       </varlistentry>
 140       <varlistentry>
 141         <term><option>size</option></term>
 142         <listitem>
 143           <para>The size of the block device at the client side. This
 144             is especially useful in conjunction with the -m
 145             option</para>
 146           <para>Can optionally be followed by one of K,k,M or
 147             m, in which case the size will be multiplied by 1024 (K
 148             or k) or 1048576 (M or m)</para>
 149         </listitem>
 150       </varlistentry>
 151       <varlistentry>
 152         <term><option>-r</option></term>
 153         <listitem>
 154           <para>Export the file read-only. If a client tries to write
 155             to a read-only exported file, it will receive an error, but
 156             the connection will stay up.</para>
 157         </listitem>
 158       </varlistentry>
 159       <varlistentry>
 160         <term><option>-m</option></term>
 161         <listitem>
 162           <para>Work with multiple files. This can be used to export
 163             blockdevices that are larger than the maximum allowed
 164             filesize on a given filesystem; i.e. when the filesystem
 165             does not allow files larger than 2GB (which is true for
 166             Linux 2.2 and below), you can use this option to store the
 167             data in multiple files and export a larger filesystem, if
 168             needed.</para>
 169           <para>
 170             To use this option, you must create a number of files
 171             with names in the format "name.X", where "name" is given as
 172             the filename argument to nbd-server, and "X" is a number
 173             starting by 0 and going up for each file.
 174           </para>
 175           <para>
 176             Allowing more flexibility for this option is planned for
 177             future versions.</para>
 178         </listitem>
 179       </varlistentry>
 180       <varlistentry>
 181         <term><option>-c</option></term>
 182         <listitem>
 183           <para>Copy on write. When this option is provided,
 184             write-operations are not done to the exported file, but to a
 185             separate file. This separate file is removed when the
 186             connection is closed, which means that serving this way will
 187             make nbd-server slow down (especially on large block devices
 188             with lots of writes), and that after disconnecting and
 189             reconnecting the client or the server, all changes are
 190             lost.</para>
 191         </listitem>
 192       </varlistentry>
 193       <varlistentry>
 194         <term><option>-C</option></term>
 195         <listitem>
 196           <para>Specify configuration file. The default configuration
 197             file, if this parameter is not specified, is
 198             <filename>$sysconfdir/nbd-server/config</filename>.</para>
 199           <para>Note that the configuration file is always parsed and
 200             the entries in the file used, even if an extra server is
 201             specified on the command line. To disable the configuration
 202             file entirely, either move it away or use the -C option to
 203             point <command>nbd-server</command>(1) to a non-existing or
 204             empty configuration file.</para>
 205           <para>Also note that if an empty, incomplete, or invalid
 206             configuration file is specified, nbd-server will produce a
 207             warning about failure to parse the config file. If the
 208             command line contains a fully specified configuration, this
 209             warning is harmless and may be ignored.</para>
 210         </listitem>
 211       </varlistentry>
 212       <varlistentry>
 213         <term><option>-M</option></term>
 214         <listitem>
 215           <para>Specify the maximum number of opened connections. If this
 216           parameter is not specified, no limit is set.</para>
 217         </listitem>
 218       </varlistentry>
 219       <varlistentry>
 220         <term><option>-d</option></term>
 221         <listitem>
 222           <para>Do not fork. Useful for debugging.</para>
 223         </listitem>
 224       </varlistentry>
 225       <varlistentry>
 226         <term><option>host list filename</option></term>
 227         <listitem>
 228           <para>This argument should contain a list of IP-addresses
 229             for hosts that may connect to the server. Wildcards are
 230             <emphasis>not</emphasis> allowed. If the file does not
 231             exist, it is ignored (and any host can connect); If the file
 232             does exist, but is empty, no host can connect. By default,
 233             the name 'nbd_server.allow' is used, and looked for in the
 234             current directory, unless nbd-server is compiled as a
 235             daemon, in which case it is looked for in the
 236             root-directory.</para>
 237         </listitem>
 238       </varlistentry>
 239       <varlistentry>
 240         <term><option>section name</option></term>
 241         <listitem>
 242           <para>If the <option>-o</option> argument is given on the
 243           command line, then &dhpackage; will output a configuration
 244           file section with this as the header that is functionally
 245           equivalent to the other options specified on the command line,
 246           and exit. This is useful for migrating pre-2.9 nbd-server
 247           initscript configuration files to the new format.</para>
 248         </listitem>
 249       </varlistentry>
 250     </variablelist>
 251
 252   </refsect1>
 253   <refsect1>
 254     <title>EXAMPLES</title>
 255     <para>Some examples of nbd-server usage:</para>
 256     <itemizedlist mark="none">
 257       <listitem>
 258         <para>To export a file /export/nbd/exp-bl-dev on port 2000:</para>
 259         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev</command></para>
 260       </listitem>
 261       <listitem>
 262         <para>To export a the same file read-only:</para>
 263         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev -r</command></para>
 264       </listitem>
 265       <listitem>
 266         <para>To export the same file read-write, but make sure
 267           changes are lost after restarting the client or the
 268           server:</para>
 269         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev
 270             -c</command></para>
 271       </listitem>
 272     </itemizedlist>
 273   </refsect1>
 274   <refsect1>
 275     <title>SEE ALSO</title>
 276
 277     <para>nbd-client (8), nbd-server (5), nbd-trdump (8)</para>
 278
 279   </refsect1>
 280   <refsect1>
 281     <title>AUTHOR</title>
 282     <para>The NBD kernel module and the NBD tools were originally
 283       written by Pavel Machek (pavel@ucw.cz)</para>
 284
 285     <para>The Linux kernel module is now maintained by Paul Clements
 286       (Paul.Clements@steeleye.com), while the userland tools are
 287       maintained by &dhusername; (&dhemail;)</para>
 288
 289     <para>On The Hurd there is a regular translator available to perform the
 290       client side of the protocol, and the use of
 291       <command>nbd-client</command> is not required. Please see the
 292       relevant documentation for more information.</para>
 293
 294     <para>This manual page was written by &dhusername; (&dhemail;) for
 295       the &debian; system (but may be used by others).  Permission is
 296       granted to copy, distribute and/or modify this document under
 297       the terms of the <acronym>GNU</acronym> General Public License,
 298       version 2, as published by the Free Software Foundation.</para>
 299
 300   </refsect1>
 301 </refentry>