man/nbd-server.1.sgml.in

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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>-V</option></arg>
  71       <arg><option>-n</option></arg>
  72       <arg><option>-d</option></arg>
  73     </cmdsynopsis>
  74   </refsynopsisdiv>
  75   <refsect1>
  76     <title>DESCRIPTION</title>
  77
  78     <para><command>&dhpackage;</command> is the server for the Linux
  79     Network Block Device (NBD). With NBD, a client can use a file,
  80     exported over the network from a server, as a block device. It can
  81     then be used for whatever purpose a normal block device (harddisk,
  82     CD-ROM, ...) can be used for.</para>
  83
  84     <para>NBD can be useful for diskless clients that need swapspace,
  85     but you can also create a filesystem on it and use it as though it
  86     were a local filesystem.</para>
  87
  88     <para><command>&dhpackage;</command> implements some security
  89     through a file called "@MAN_SYSCONFDIR@/nbd-server/allow" (by default; a
  90     different file can be chosen with the '-l' option or through a
  91     config file specification). This file must list the IP-addresses or
  92     network masks of clients that are allowed to connect. If it does not
  93     exist, all clients are able to connect. If the file is empty, no
  94     clients can connect.</para>
  95
  96     <para>Note that while the command line allows for specifying an
  97     export, the use of this option is deprecated. It is preferred to
  98     make use of a configuration file instead, the format of which is
  99     defined in nbd-server(5).</para>
 100
 101    <para>While nbd-server is running, new exports can be added by
 102    re-writing configuration files and then sending SIGHUP to
 103    nbd-server. SIGHUP causes nbd-server to re-read its configuration
 104    files and to start serving all new exports which were not served
 105    earlier. Reconfiguration does not modify any existing export, it only
 106    appends new ones.</para>
 107   </refsect1>
 108   <refsect1>
 109     <title>OPTIONS</title>
 110
 111     <variablelist>
 112       <varlistentry>
 113         <term>ip</term>
 114         <listitem>
 115           <para>The ip address the server should listen on. This may
 116           be an IPv4 address, an IPv6 address, or a hostname. In the
 117           latter case, nbd-server will do a hostname lookup for the
 118           name specified, and will listen on the first address that is
 119           returned. For compatibility with past versions of
 120           nbd-server, if an IPv4 address is specified, the @ sign that
 121           serves as separator between the address and port may be
 122           replaced by a colon.</para>
 123           <para>If this parameter is not specified, nbd-server will
 124           listen on all local addresses on both IPv4 and IPv6. To
 125           limit to IPv4, specify the address as 0.0.0.0; to limit to
 126           IPv6, specify it as ::.</para>
 127         </listitem>
 128       </varlistentry>
 129       <varlistentry>
 130         <term><option>port</option>
 131         </term>
 132         <listitem>
 133           <para>The port the server should listen to. A valid port is
 134             any number between 1 and 65536; if 0 is used, nbd-server
 135             will listen on stdin (so that nbd-server can be ran from
 136             inetd)</para>
 137         </listitem>
 138       </varlistentry>
 139       <varlistentry>
 140         <term><option>filename</option></term>
 141         <listitem>
 142           <para>The filename of the file that should be exported. This
 143           can be any file, including "real" blockdevices (i.e. a file
 144           from /dev). If the filename includes the literal string
 145           "%s", then this %s will be substituded with the IP-address
 146           of the client trying to connect.</para>
 147         </listitem>
 148       </varlistentry>
 149       <varlistentry>
 150         <term><option>size</option></term>
 151         <listitem>
 152           <para>The size of the block device at the client side. This
 153             is especially useful in conjunction with the -m
 154             option</para>
 155           <para>Can optionally be followed by one of K,k,M or
 156             m, in which case the size will be multiplied by 1024 (K
 157             or k) or 1048576 (M or m)</para>
 158         </listitem>
 159       </varlistentry>
 160       <varlistentry>
 161         <term><option>-r</option></term>
 162         <listitem>
 163           <para>Export the file read-only. If a client tries to write
 164             to a read-only exported file, it will receive an error, but
 165             the connection will stay up.</para>
 166         </listitem>
 167       </varlistentry>
 168       <varlistentry>
 169         <term><option>-m</option></term>
 170         <listitem>
 171           <para>Work with multiple files. This can be used to export
 172             blockdevices that are larger than the maximum allowed
 173             filesize on a given filesystem; i.e. when the filesystem
 174             does not allow files larger than 2GB (which is true for
 175             Linux 2.2 and below), you can use this option to store the
 176             data in multiple files and export a larger filesystem, if
 177             needed.</para>
 178           <para>
 179             To use this option, you must create a number of files
 180             with names in the format "name.X", where "name" is given as
 181             the filename argument to nbd-server, and "X" is a number
 182             starting by 0 and going up for each file.
 183           </para>
 184           <para>
 185             Allowing more flexibility for this option is planned for
 186             future versions.</para>
 187         </listitem>
 188       </varlistentry>
 189       <varlistentry>
 190         <term><option>-c</option></term>
 191         <listitem>
 192           <para>Copy on write. When this option is provided,
 193             write-operations are not done to the exported file, but to a
 194             separate file. This separate file is removed when the
 195             connection is closed, which means that serving this way will
 196             make nbd-server slow down (especially on large block devices
 197             with lots of writes), and that after disconnecting and
 198             reconnecting the client or the server, all changes are
 199             lost.</para>
 200         </listitem>
 201       </varlistentry>
 202       <varlistentry>
 203         <term><option>-C</option></term>
 204         <listitem>
 205           <para>Specify configuration file. The default configuration
 206             file, if this parameter is not specified, is
 207             <filename>@MAN_SYSCONFDIR@/nbd-server/config</filename>.</para>
 208           <para>Note that the configuration file is always parsed and
 209             the entries in the file used, even if an extra server is
 210             specified on the command line. To disable the configuration
 211             file entirely, either move it away or use the -C option to
 212             point <command>nbd-server</command>(1) to a non-existing or
 213             empty configuration file.</para>
 214           <para>Also note that if an empty, incomplete, or invalid
 215             configuration file is specified, nbd-server will produce a
 216             warning about failure to parse the config file. If the
 217             command line contains a fully specified configuration, this
 218             warning is harmless and may be ignored.</para>
 219         </listitem>
 220       </varlistentry>
 221       <varlistentry>
 222         <term><option>-M</option></term>
 223         <listitem>
 224           <para>Specify the maximum number of opened connections. If this
 225           parameter is not specified, no limit is set.</para>
 226         </listitem>
 227       </varlistentry>
 228       <varlistentry>
 229         <term><option>-V</option></term>
 230         <listitem>
 231           <para>Output the version of nbd-server, and exit.</para>
 232         </listitem>
 233       </varlistentry>
 234       <varlistentry>
 235         <term><option>-n</option></term>
 236         <listitem>
 237           <para>Do not daemonize the main process. In contrast
 238           to <option>-d</option>, this still allows to fork the
 239           serving process for a client from the main process.</para>
 240         </listitem>
 241       </varlistentry>
 242       <varlistentry>
 243         <term><option>-d</option></term>
 244         <listitem>
 245           <para>Do not fork. Useful for debugging.
 246           Implies <option>-n</option>.</para>
 247         </listitem>
 248       </varlistentry>
 249       <varlistentry>
 250         <term><option>host list filename</option></term>
 251         <listitem>
 252           <para>This argument should contain a list of IP-addresses
 253             for hosts that may connect to the server. Wildcards are
 254             <emphasis>not</emphasis> allowed. If the file does not
 255             exist, it is ignored (and any host can connect); If the file
 256             does exist, but is empty, no host can connect. By default,
 257             the name 'nbd_server.allow' is used, and looked for in the
 258             current directory, unless nbd-server is compiled as a
 259             daemon, in which case it is looked for in the
 260             root-directory.</para>
 261         </listitem>
 262       </varlistentry>
 263       <varlistentry>
 264         <term><option>section name</option></term>
 265         <listitem>
 266           <para>If the <option>-o</option> argument is given on the
 267           command line, then &dhpackage; will output a configuration
 268           file section with this as the header that is functionally
 269           equivalent to the other options specified on the command line,
 270           and exit. This is useful for migrating pre-2.9 nbd-server
 271           initscript configuration files to the new format.</para>
 272         </listitem>
 273       </varlistentry>
 274     </variablelist>
 275
 276   </refsect1>
 277   <refsect1>
 278     <title>EXAMPLES</title>
 279     <para>Some examples of nbd-server usage:</para>
 280     <itemizedlist mark="none">
 281       <listitem>
 282         <para>To export a file /export/nbd/exp-bl-dev on port 2000:</para>
 283         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev</command></para>
 284       </listitem>
 285       <listitem>
 286         <para>To export a the same file read-only:</para>
 287         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev -r</command></para>
 288       </listitem>
 289       <listitem>
 290         <para>To export the same file read-write, but make sure
 291           changes are lost after restarting the client or the
 292           server:</para>
 293         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev
 294             -c</command></para>
 295       </listitem>
 296     </itemizedlist>
 297   </refsect1>
 298   <refsect1>
 299     <title>SEE ALSO</title>
 300
 301     <para>nbd-client (8), nbd-server (5), nbd-trdump (8)</para>
 302
 303   </refsect1>
 304   <refsect1>
 305     <title>AUTHOR</title>
 306     <para>The NBD kernel module and the NBD tools were originally
 307       written by Pavel Machek (pavel@ucw.cz)</para>
 308
 309     <para>The Linux kernel module is now maintained by Paul Clements
 310       (Paul.Clements@steeleye.com), while the userland tools are
 311       maintained by &dhusername; (&dhemail;)</para>
 312
 313     <para>On The Hurd there is a regular translator available to perform the
 314       client side of the protocol, and the use of
 315       <command>nbd-client</command> is not required. Please see the
 316       relevant documentation for more information.</para>
 317
 318     <para>This manual page was written by &dhusername; (&dhemail;) for
 319       the &debian; system (but may be used by others).  Permission is
 320       granted to copy, distribute and/or modify this document under
 321       the terms of the <acronym>GNU</acronym> General Public License,
 322       version 2, as published by the Free Software Foundation.</para>
 323
 324   </refsect1>
 325 </refentry>