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Network Block Device
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.travis Make the travis stuff work (after some testing on a separate branch)
doc Add license statement
gznbd gznbd: use atoll() to convert size argument
man Update documentation of config file in light of oldstyle removal
tests Drop support for the oldstyle protocol
.gitignore Make a start with a library
.travis.yml Revert "Enable automatic coverity coverage"
COPYING Add the actual text of the GPLv2, as the license requires us to
CodingStyle r176: Add CodingStyle document Wire gznbd into general Modernize README, and point to sourceforge download pages for the ben… Move nbd-trdump.8 to nbd-trdump.1, where it belongs.
cliserv.c Unbreak --enable-syslog
cliserv.h Unbreak --enable-syslog Don't forget
coverity_model.c Create Coverity model
lfs.h Improve indentation to avoid this kind of thing from happening again.
make-integrityhuge.c Add integrity test for huge writes. Fix speed calc problem.
maketr Add transaction log support and integrity test
nbd-client.c Groan
nbd-debug.h Move size_autodetect to library
nbd-server.c Fix NULL pointer dereference
nbd-trdump.c Don't send to syslog from nbd-trdump
nbd.h add support for NBD_CMD_TRIM, update docs
nbdsrv.c Fix various warnings that pop up by default with gcc 4.9
nbdsrv.h Implement new config file option "cowdir"
netdb-compat.h Fix typo in include guard test


Coverity Scan Build Status

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Welcome to the NBD userland support files!

This package contains nbd-server and nbd-client.

To install the package, do the normal configure/make/make install dance. You'll need to install it on both the client and the server.

Note that released nbd tarballs are found on sourceforge.

Using NBD is quite easy. First, on the client, you need to load the module and, if you're not using udev, to create the device nodes:

# modprobe nbd
# cd /dev
# ./MAKEDEV nbd0

(if you need more than one NBD device, repeat the above command for nbd1, nbd2, ...)

Next, write a configuration file for the server. An example looks like this:

# This is a comment
   # The [generic] section is required, even if nothing is specified
    # there.
    # When either of these options are specified, nbd-server drops
    # privileges to the given user and group after opening ports, but
    # _before_ opening files.
    user = nbd
    group = nbd
    # Since version 2.9.17, nbd-server will do exports on a name
    # basis (the used name is the name of the section in which the
    # export is specified). This however required an incompatible
    # protocol change. To enable backwards-compatible port-based
    # exports, uncomment the following line:
    # oldstyle = true
    exportname = /export/nbd/export1-file
    # The following line will be ignored unless the 
    # "oldstyle = true" line in the generic section above is
    # enabled.
    port = 12345
    authfile = /export/nbd/export1-authfile
    timeout = 30
    filesize = 10000000
    readonly = false
    multifile = false
    copyonwrite = false
    prerun = dd if=/dev/zero of=%s bs=1k count=500
    postrun = rm -f %s
    exportname = /export/nbd/experiment
    # The other options are all optional, except this one in case
    # the oldstyle option is used in [generic]:
    # port = 12346

The configuration file is parsed with GLib's GKeyFile, which parses key files as they are specified in the Desktop Entry Specification, as can be found at While this format was not intended to be used for configuration files, the glib API is flexible enough for it to be used as such.

Now start the server:

nbd-server -C /path/to/configfile

Note that the filename must be an absolute path; i.e., something like /path/to/file, not ../file. See the nbd-server manpage for details on any available options.

Finally, you'll be able to start the client:

nbd-client <hostname> -N <export name> <nbd device>


nbd-client -N otherexport /dev/nbd0

will use the second export in the above example (the one that exports /export/nbd/experiment)

nbd-client must be ran as root; the same is not true for nbd-server (but do make sure that /var/run is writeable by the server that nbd-server runs as; otherwise, you won't get a PID file, though the server will keep running).

The old command-line port-only way of exporting something is still supported, but it is deprecated.

There are packages (or similar) available for the following operating systems:

  • Debian (and derivatives, like Ubuntu): nbd-client and nbd-server, since Debian woody.
  • Gentoo: the nbd ebuild in the sys-block category, available in Portage since 2002.
  • FreeBSD: net/nbd-server, available in the ports tree since 2003. FreeBSD doesn't have kernel support for NBD, so obviously the client isn't built there.
  • SuSE: nbd, in SuSE 10.0
  • Fedora: nbd, since Fedora 7
  • uClibc's buildroot script also seems to have support for NBD.

If you're packaging NBD for a different operating system that isn't in the above list, I'd like to know about it.

For questions, please use the mailinglist.

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