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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">
25 <!ENTITY debian "<productname>Debian GNU/Linux</productname>">
26 <!ENTITY gnu "<acronym>GNU</acronym>">
40 <holder>&dhusername;</holder>
50 <refname>&dhpackage;</refname>
52 <refpurpose>serve a file as a block device to other computers
53 running the &gnu;/Linux(tm) or &gnu;/Hurd Operating
58 <command>&dhpackage; </command>
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>
72 <title>DESCRIPTION</title>
74 <para><command>&dhpackage;</command> is the server for the Linux
75 Network Block Device (NBD). With NBD, a client can use a file,
76 exported over the network from a server, as a block device. It can
77 then be used for whatever purpose a normal block device (harddisk,
78 CD-ROM, ...) can be used for.</para>
80 <para>NBD can be useful for diskless clients that need swapspace,
81 but you can also create a filesystem on it and use it as though it
82 were a local filesystem.</para>
84 <para><command>&dhpackage;</command> implements some security
85 through a file called "nbd_server.allow" in the current directory (by default; a different file can be chosen with the '-l' option).
86 This file must list the IP-addresses of clients that are allowed
87 to connect. If it does not exist, all clients are able to connect.
88 If the file is empty, no clients can connect.</para>
91 <title>OPTIONS</title>
97 <para>The ip address the server should listen on. If
98 omitted, 0.0.0.0 (aka "any address") is used.</para>
102 <term><option>port</option>
105 <para>The port the server should listen to. A valid port is
106 any number between 1 and 65536; if 0 is used, nbd-server
107 will listen on stdin (so that nbd-server can be ran from
112 <term><option>filename</option></term>
114 <para>The filename of the file that should be exported. This
115 can be any file, including "real" blockdevices (i.e. a file
116 from /dev). If the filename includes the literal string
117 "%s", then this %s will be substituded with the IP-address
118 of the client trying to connect.</para>
122 <term><option>size</option></term>
124 <para>The size of the block device at the client side. This
125 is especially usefull in conjunction with the -m
127 <para>Can optionally be followed by one of K,k,M or
128 m, in which case the size will be multiplied by 1024 (K
129 or k) or 1048576 (M or m)</para>
133 <term><option>-r</option></term>
135 <para>Export the file read-only. If a client tries to write
136 to a read-only exported file, it will receive an error, but
137 the connection will stay up.</para>
141 <term><option>-m</option></term>
143 <para>Work with multiple files. This can be used to export
144 blockdevices that are larger than the maximum allowed
145 filesize on a given filesystem; i.e. when the filesystem
146 does not allow files larger than 2GB (which is true for
147 Linux 2.2 and below), you can use this option to store the
148 data in multiple files and export a larger filesystem, if
151 To use this option, you must create a number of files
152 with names in the format "name.X", where "name" is given as
153 the filename argument to nbd-server, and "X" is a number
154 starting by 0 and going up for each file.
157 Allowing more flexibility for this option is planned for
158 future versions.</para>
162 <term><option>-c</option></term>
164 <para>Copy on write. When this option is provided,
165 write-operations are not done to the exported file, but to a
166 separate file. This separate file is removed when the
167 connection is closed, which means that serving this way will
168 make nbd-server slow down (especially on large block devices
169 with lots of writes), and that after disconnecting and
170 reconnecting the client or the server, all changes are
175 <term><option>-C</option></term>
177 <para>Specify configuration file. The default configuration
178 file, if this parameter is not specified, is
179 <filename>@sysconfdir@/nbd-server/config</filename>.</para>
180 <para>Note that the configuration file is always parsed and
181 the entries in the file used, even if an extra server is
182 specified on the command line. To disable the configuration
183 file entirely, either move it away or use the -C option to
184 point <command>nbd-server</command>(1) to a non-existing or
185 empty configuration file.</para>
186 <para>Also note that if an empty, incomplete, or invalid
187 configuration file is specified, nbd-server will produce a
188 warning about failure to parse the config file. If the
189 command line contains a fully specified configuration, this
190 warning is harmless and may be ignored.</para>
194 <term><option>host list filename</option></term>
196 <para>This argument should contain a list of IP-addresses
197 for hosts that may connect to the server. Wildcards are
198 <emphasis>not</emphasis> allowed. If the file does not
199 exist, it is ignored (and any host can connect); If the file
200 does exist, but is empty, no host can connect. By default,
201 the name 'nbd_server.allow' is used, and looked for in the
202 current directory, unless nbd-server is compiled as a
203 daemon, in which case it is looked for in the
204 root-directory.</para>
208 <term><option>section name</option></term>
210 <para>If the <option>-o</option> argument is given on the
211 command line, then &dhpackage; will output a configuration
212 file section with this as the header that is functionally
213 equivalent to the other options specified on the command line,
214 and exit. This is useful for migrating pre-2.9 nbd-server
215 initscript configuration files to the new format.</para>
222 <title>EXAMPLES</title>
223 <para>Some examples of nbd-server usage:</para>
224 <itemizedlist mark="none">
226 <para>To export a file /export/nbd/exp-bl-dev on port 2000:</para>
227 <para><command>nbd-server 2000 /export/nbd/exp-bl-dev</command></para>
230 <para>To export a the same file read-only:</para>
231 <para><command>nbd-server 2000 /export/nbd/exp-bl-dev -r</command></para>
234 <para>To export the same file read-write, but make sure
235 changes are lost after restarting the client or the
237 <para><command>nbd-server 2000 /export/nbd/exp-bl-dev
243 <title>SEE ALSO</title>
245 <para>nbd-client (8), nbd-server (5), http://nbd.sourceforge.net/roadmap.html</para>
249 <title>AUTHOR</title>
250 <para>The NBD kernel module and the NBD tools were originally
251 written by Pavel Machek (pavel@ucw.cz)</para>
253 <para>The Linux kernel module is now maintained by Paul Clements
254 (Paul.Clements@steeleye.com), while the userland tools are
255 maintained by &dhusername; (&dhemail;)</para>
257 <para>On The Hurd there is a regular translator available to perform the
258 client side of the protocol, and the use of
259 <command>nbd-client</command> is not required. Please see the
260 relevant documentation for more information.</para>
262 <para>This manual page was written by &dhusername; (&dhemail;) for
263 the &debian; system (but may be used by others). Permission is
264 granted to copy, distribute and/or modify this document under
265 the terms of the <acronym>GNU</acronym> General Public License,
266 version 2, as published by the Free Software Foundation.</para>
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