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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: 2006-10-18 15:01:57 +0200 (wo, 18 okt 2006) $</date>">
17 <!-- SECTION should be 1-8, maybe w/ subsection other parameters are
18 allowed: see man(7), man(1). -->
19 <!ENTITY dhsection "<manvolnum>5</manvolnum>">
20 <!ENTITY dhemail "<email>wouter@debian.org</email>">
21 <!ENTITY dhusername "Wouter Verhelst">
22 <!ENTITY dhucpackage "<refentrytitle>NBD-SERVER</refentrytitle>">
23 <!ENTITY dhpackage "/etc/nbd-server/config">
25 <!ENTITY debian "<productname>Debian GNU/Linux</productname>">
26 <!ENTITY gnu "<acronym>GNU</acronym>">
40 <holder>&dhusername;</holder>
50 <refname>&dhpackage;</refname>
52 <refpurpose>configuration file for nbd-server</refpurpose>
56 <command>&dhpackage; </command>
61 <title>DESCRIPTION</title>
63 <para><command>&dhpackage;</command> allows to configure the
67 <filename>@sysconfdir@/nbd-server/config</filename> is the default
68 configuration file, this can be varied with the <option>-C</option>
69 option to <command>nbd-server</command>(1).
72 The configuration file consists of section header lines, comment
73 lines, and option lines.
76 A section header is a unique name that
77 is enclosed in square brackets ("[" and "]"). A section header
78 denotes the beginning of a section; a section continues until
79 the next section or the end of the file, whichever is first. The
80 first section in the configuration file must be called
81 <option>generic</option>, and is used for global options that
82 apply to more than one export. This section must always be
83 present, even if it holds no options. Every other section
84 defines one export; the names of these sections are not
85 important, except that you should take care to make sure that
86 each section name is unique (future versions of
87 <command>nbd-server</command> may use the section name to refer
91 A comment line is a line that starts with optional whitespace,
92 followed by a pound sign ("#"), and continues until the end of
93 the line. Comments may <emphasis>not</emphasis> be used on
94 option lines or section header lines.
97 An option line is a line that starts with an option name,
98 followed by an equals sign ("="), followed by the option
99 value. An option can be of type string, of type integer, or of
100 type boolean. The value of a boolean option can be denoted with
101 either true or false (so not yes, no, on, off, 1, or 0); all
102 booleans default to false unless specified otherwise; no value
103 may be quoted (always enter it directly); for a string option,
104 leading whitespace is stripped (but trailing whitespace is not).
109 <title>OPTIONS FOR SECTION [generic]</title>
111 <!-- These are in alphabetical order, please keep it that way -->
114 <term><option>group</option></term>
120 The name of the group this server must run as. If this
121 parameter is not specified, then nbd-server will not
122 attempt to change its GID (so the GID it runs as will be
123 the primary group of the user who starts nbd-server). If
124 it is specified, then nbd-server will change its GID after
125 opening ports, but before accepting connections or opening
131 <term><option>user</option></term>
137 The name of the user this server must run as. If this
138 parameter is not specified, then nbd-server will not
139 attempt to change its UID (so the UID it runs as will be
140 the user who starts nbd-server). If it is specified, then
141 nbd-server will change its UID after opening ports, but
142 before accepting connections or opening files.
149 <title>OPTIONS FOR EXPORT SECTIONS</title>
151 <!-- These are in alphabetical order, please keep it that way -->
154 <term><option>authfile</option></term>
157 Optional; string; default
158 <filename>@sysconfdir@/nbd-server/allow</filename>.
161 The name of the authorization file for this export. This
162 file should contain one line per IP-address, or per
163 network (which must be specified in CIDR-style
164 <option><replaceable>network</replaceable>/<replaceable>masklen</replaceable></option>)
165 and must not contain empty lines. If the file
166 does not exist, everyone is allowed to connect. If the
167 file exists but is empty, nobody is allowed to
168 connect. Otherwise, <command>nbd-server</command> will
169 only allow clients to connect whose IP-adres is listed in
172 <para>Corresponds to the <option>-l</option> option on the
177 <term><option>autoreadonly</option></term>
179 <para>Optional; boolean.</para>
181 If this option is set to true, then
182 <command>nbd-server</command> will automatically switch to
183 readonly if it cannot write to the file.
185 <para>Does not have a corresponding command-line
187 <para>TODO: verify whether this option actually works as
188 documented. I have a feeling I've been terribly
194 <term><option>copyonwrite</option></term>
200 Whether this is a copy-on-write export. If it is, then any
201 writes to this export will not be written to the master
202 file, but to a separate file which will be removed upon
203 disconnect. The result of using this option is that
204 nbd-server will be slower, and that any writes will be
205 lost upon disconnect.
207 <para>Corresponds to the <option>-c</option> option on the
212 <term><option>exportname</option></term>
214 <para>Required; string.</para>
216 The name of the file that will be exported. This must be a
217 fully-qualified path and filename; relative paths are not
221 Note that <command>nbd-server</command> will only try to
222 find and open the exported file when a client actually
223 connects; as a result, <command>nbd-server</command> must
224 be able to open and read this file
225 <emphasis>after</emphasis> changing to the user and group
226 that have been specified by use of the
227 <option>user</option> and <option>group</option> options;
228 also, <command>nbd-server</command> will only detect
229 errors in this option upon connection of a client.
231 <para>When specified on the command line, this should be the
237 <term><option>filesize</option></term>
239 <para>Optional; integer; default autodetected.</para>
241 Disable autodetection of file or block device size, and
242 forcibly specify a size. Sizes must be specified in
243 bytes. If the <option>multifile</option> option is in
244 effect, this option specifies the size of the
245 <emphasis>entire</emphasis> export, not of individual
248 <para>When specified on the command line, this should be the
254 <term>listenaddr</term>
256 <para>Optional; string</para>
257 <para>If this option is set, it should contain the local IP
258 address (in "dotted-quad" notation) on which we should
259 listen to <command>nbd-client</command>(8) connections. If
260 it is not set, 0.0.0.0 is used (i.e., "listen on all local
261 IP addresses")</para>
265 <term><option>multifile</option></term>
267 <para>Optional; boolean.</para>
269 If this option is set to true, then
270 <command>nbd-server</command> will search for files of the
272 <replaceable>exportname</replaceable>.<replaceable>integer</replaceable>,
273 with <replaceable>exportname</replaceable> being the
274 filename that would otherwise have been used (after
275 name transformation for virtualization, if any, has been
276 performed) and <replaceable>integer</replaceable> an
277 integer number, starting with 0 and ending when no more
281 The size of the individual files will be autodetected,
282 <emphasis>even</emphasis> if the <option>filesize</option>
283 option has been specified. See the documentation for the
284 <option>multifile</option> for details.
287 Corresponds to the <option>-m</option> option on the
293 <term><option>port</option></term>
295 <para>Required; integer.</para>
297 The port on which this export is to be served. Currently
298 it is not possible to export multiple block devices on the
299 same port unless virtualization is used; future versions
300 of <command>nbd-server</command> may add this
304 When specified on the command line, this should be the
310 <term><option>readonly</option></term>
312 <para>Optional; boolean.</para>
314 Disallow writes to the device. If this option is
315 specified, <command>nbd-server</command> will issue an
316 error to any client that tries to write to the device.
319 Use of this option in conjunction with
320 <option>copyonwrite</option> is possible, but silly.
322 <para>Corresponds to the <option>-r</option> option on the
327 <term><option>sdp</option></term>
329 <para>Optional; boolean.</para>
331 When this option is enabled, <command>nbd-server</command>
332 will use the Socket Direct Protocol (SDP) to serve the
333 export, rather than just IP. This is faster, but requires
334 special hardware (usually something like InfiniBand) and
335 support in the kernel.
338 Additionally, support for this option must be enabled at
339 compile time, using the <option>--enable-sdp</option> option
340 to the <command>configure</command> script. If this option
341 is found in a configuration file and
342 <command>nbd-server</command> does not have support for SDP,
343 then <command>nbd-server</command> will exit with an error
349 <term><option>sparse_cow</option></term>
351 <para>Optional; boolean.</para>
353 When this option is enabled, <command>nbd-server</command>
354 will use sparse files to implement the copy-on-write
355 option; such files take up less space then they appear to,
356 which allows <command>nbd-server</command> to handle the
357 file as if it was just as large as the block device it's
361 If this option is disabled, <command>nbd-server</command>
362 will map every newly written block to the end of the
363 copy-on-write file, which means that
364 <command>nbd-server</command> will have to lseek(2) to the
365 right position after every 4096-byte block.
368 Using this option may be faster when much is being written
374 <term><option>timeout</option></term>
376 <para>Optional; integer; default 0</para>
378 How many seconds a connection may be idle for this
379 export. When a connection is idle for a longer time,
380 <command>nbd-server</command> will forcibly disconnect the
381 connection. If you specify 0 (the default), then a
382 connection may be idle forever.
385 Corresponds to the <option>-a</option> option on the
391 <term><option>virtstyle</option></term>
393 <para>Optional; string; default "ipliteral"</para>
395 Defines the style of virtualization. Virtualization allows
396 one to create one export that will serve a different file
397 depending on the IP address that is connecting. When
398 virtualization is There are three types of virtualization
399 that <command>nbd-server</command> supports:
403 <term><option>none</option></term>
406 No virtualization. Will attempt to open the filename
407 as it was written, even if it contains '%s' in the
413 <term><option>ipliteral</option></term>
416 <command>nbd-server</command> will look for the
417 literal string '%s' in the
418 <option>exportname</option>, and replace it by the
419 IP address of the connecting host in dotted-quad
420 notation. The string that results from this
421 transformation will be used as an absolute pathname
422 that <command>nbd-server</command> will attempt to
423 open. As an example, if a client connects from
424 192.168.1.100 and <option>exportname</option> is
425 specified as <filename>/export/%s</filename>, then
426 nbd-server will attempt to serve
427 <filename>/export/192.168.1.100</filename>
432 <term><option>iphash</option></term>
435 Same as above, except that
436 <command>nbd-server</command> will replace the dots
437 in the IP address by forward slashes ('/'); in the
438 same example, <command>nbd-server</command> would
439 open <filename>/export/192/168/1/100</filename>
445 <term><option>cidrhash</option></term>
448 This option requires one to add a space and a number
449 after it. <command>nbd-server</command> will use the
450 number as a network mask in CIDR style, and use that
451 as a hash cutoff point. In the above example, if
452 <option>virtstyle</option> has been specified as
453 <constant>cidrhash 16</constant>, then
454 <command>nbd-server</command> will try to open
455 <filename>/export/192.168.0.0/192.168.1.100</filename>;
456 if <option>virtstyle</option> were specified as
457 <constant>cidrhash 26</constant>, then
458 <command>nbd-server</command> will try to open
459 <filename>/export/192.168.1.64/192.168.1.100</filename>.
467 <term><option>prerun</option></term>
469 <para>Optional; string</para>
471 If specified, then this command will be ran after a
472 client has connected to the server (and has been
473 accepted), but before the server starts serving. If
474 the command contains the literal string '%s', then
475 this string will be replaced by the filename of the
476 file which nbd-server wants to export.
479 This is useful to create export files on the fly, or
480 to verify that a file can be used for export, to
481 write something to a log file, or similar.
484 If the command runs with a non-zero exit status,
485 then nbd-server will assume the export will fail,
486 and refuse to serve it.
491 <term><option>postrun</option></term>
493 <para>Optional; string</para>
495 If specified, then it is assumed to be a command
496 that will be ran when a client has
497 disconnected. This can be useful to clean up
498 whatever <option>prerun</option> has set up, to log
499 something, or similar.
502 If the literal string '%s' is present in the
503 command, it will be replaced by the file name that
504 has just been closed.
507 In contrast to the <option>prerun</option> option,
508 the exit state of <option>postrun</option> is
509 <emphasis>ignored</emphasis>.
517 <title>SEE ALSO</title>
519 <para>nbd-server (1), nbd-client (8),
520 http://nbd.sourceforge.net/roadmap.html</para>
524 <title>AUTHOR</title>
525 <para>The NBD kernel module and the NBD tools were originally
526 written by Pavel Machek (pavel@ucw.cz)</para>
528 <para>The Linux kernel module is now maintained by Paul Clements
529 (Paul.Clements@steeleye.com), while the userland tools are
530 maintained by &dhusername; (&dhemail;)</para>
532 <para>On The Hurd there is a regular translator available to perform the
533 client side of the protocol, and the use of
534 <command>nbd-client</command> is not required. Please see the
535 relevant documentation for more information.</para>
537 <para>This manual page was written by &dhusername; (&dhemail;) for
538 the &debian; system (but may be used by others). Permission is
539 granted to copy, distribute and/or modify this document under
540 the terms of the <acronym>GNU</acronym> General Public License,
541 version 2, as published by the Free Software Foundation.</para>
545 <title>EXAMPLES</title>
546 <para>A simple <command>nbd-server</command> configuration file
547 would look like this:</para>
551 exportname = /export/blkdev
554 <para>For increased security, one might want to create an
555 authorization file, and set the UID and GID to run as:</para>
561 exportname = /export/blkdev
563 authfile = /etc/nbd-server/allow
565 <para>With /etc/nbd-server/allow containing the following:</para>
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