rsyncd.conf(5) rsyncd.conf(5)
NAME
rsyncd.conf - configuration file for rsync in daemon mode
SYNOPSIS
rsyncd.conf
DESCRIPTION
The rsyncd.conf file is the runtime configuration file for rsync when
run as an rsync daemon.
The rsyncd.conf file controls authentication, access, logging and
available modules.
FILE FORMAT
The file consists of modules and parameters. A module begins with the
name of the module in square brackets and continues until the next
module begins. Modules contain parameters of the form 'name = value'.
The file is line-based -- that is, each newline-terminated line
represents either a comment, a module name or a parameter.
Only the first equals sign in a parameter is significant. Whitespace
before or after the first equals sign is discarded. Leading, trailing
and internal whitespace in module and parameter names is irrelevant.
Leading and trailing whitespace in a parameter value is discarded.
Internal whitespace within a parameter value is retained verbatim.
Any line beginning with a hash (#) is ignored, as are lines containing
only whitespace.
Any line ending in a \ is "continued" on the next line in the customary
UNIX fashion.
The values following the equals sign in parameters are all either a
string (no quotes needed) or a boolean, which may be given as yes/no,
0/1 or true/false. Case is not significant in boolean values, but is
preserved in string values.
LAUNCHING THE RSYNC DAEMON
The rsync daemon is launched by specifying the --daemon option to
rsync.
The daemon must run with root privileges if you wish to use chroot, to
bind to a port numbered under 1024 (as is the default 873), or to set
file ownership. Otherwise, it must just have permission to read and
write the appropriate data, log, and lock files.
You can launch it either via inetd, as a stand-alone daemon, or from an
rsync client via a remote shell. If run as a stand-alone daemon then
just run the command "rsync --daemon" from a suitable startup script.
When run via inetd you should add a line like this to /etc/services:
rsync 873/tcp
and a single line something like this to /etc/inetd.conf:
rsync stream tcp nowait root /usr/bin/rsync rsyncd --daemon
Replace "/usr/bin/rsync" with the path to where you have rsync
installed on your system. You will then need to send inetd a HUP
signal to tell it to reread its config file.
Note that you should not send the rsync daemon a HUP signal to force it
to reread the rsyncd.conf file. The file is re-read on each client
connection.
GLOBAL OPTIONS
The first parameters in the file (before a [module] header) are the
global parameters.
You may also include any module parameters in the global part of the
config file in which case the supplied value will override the default
for that parameter.
motd file
The "motd file" option allows you to specify a "message of the
day" to display to clients on each connect. This usually
contains site information and any legal notices. The default is
no motd file.
pid file
The "pid file" option tells the rsync daemon to write its
process ID to that file.
port You can override the default port the daemon will listen on by
specifying this value (defaults to 873). This is ignored if the
daemon is being run by inetd, and is superseded by the --port
command-line option.
address
You can override the default IP address the daemon will listen
on by specifying this value. This is ignored if the daemon is
being run by inetd, and is superseded by the --address command-
line option.
socket options
This option can provide endless fun for people who like to tune
their systems to the utmost degree. You can set all sorts of
socket options which may make transfers faster (or slower!).
Read the man page for the setsockopt() system call for details
on some of the options you may be able to set. By default no
special socket options are set. These settings are superseded
by the --sockopts command-line option.
MODULE OPTIONS
After the global options you should define a number of modules, each
module exports a directory tree as a symbolic name. Modules are
exported by specifying a module name in square brackets [module]
followed by the options for that module.
comment
The "comment" option specifies a description string that is
displayed next to the module name when clients obtain a list of
available modules. The default is no comment.
path The "path" option specifies the directory in the daemon's
filesystem to make available in this module. You must specify
this option for each module in rsyncd.conf.
use chroot
If "use chroot" is true, the rsync daemon will chroot to the
"path" before starting the file transfer with the client. This
has the advantage of extra protection against possible
implementation security holes, but it has the disadvantages of
requiring super-user privileges, of not being able to follow
symbolic links that are either absolute or outside of the new
root path, and of complicating the preservation of users and
groups by name (see below). When "use chroot" is false, rsync
will: (1) munge symlinks by default for security reasons (see
"munge symlinks" for a way to turn this off, but only if you
trust your users), (2) substitute leading slashes in absolute
paths with the module's path (so that options such as
--backup-dir, --compare-dest, etc. interpret an absolute path as
rooted in the module's "path" dir), and (3) trim ".." path
elements from args if rsync believes they would escape the
chroot. The default for "use chroot" is true, and is the safer
choice (especially if the module is not read-only).
When this option is enabled, rsync will not attempt to map users
and groups by name (by default), but instead copy IDs as though
--numeric-ids had been specified. In order to enable name-
mapping, rsync needs to be able to use the standard library
functions for looking up names and IDs (i.e. getpwuid() ,
getgrgid() , getpwname() , and getgrnam() ). This means the
rsync process in the chroot hierarchy will need to have access
to the resources used by these library functions (traditionally
/etc/passwd and /etc/group, but perhaps additional dynamic
libraries as well).
If you copy the necessary resources into the module's chroot
area, you should protect them through your OS's normal
user/group or ACL settings (to prevent the rsync module's user
from being able to change them), and then hide them from the
user's view via "exclude" (see how in the discussion of that
option). At that point it will be safe to enable the mapping of
users and groups by name using the "numeric ids" daemon option
(see below).
Note also that you are free to setup custom user/group
information in the chroot area that is different from your
normal system. For example, you could abbreviate the list of
users and groups.
numeric ids
Enabling the "numeric ids" option disables the mapping of users
and groups by name for the current daemon module. This prevents
the daemon from trying to load any user/group-related files or
libraries. Enabling this option makes the transfer behave as if
the client had passed the --numeric-ids command-line option. By
default, this parameter is enabled for chroot modules and
disabled for non-chroot modules.
A chroot-enabled module should not have this option enabled
unless you've taken steps to ensure that the module has the
necessary resources it needs to translate names, and that it is
not possible for a user to change those resources.
munge symlinks
The "munge symlinks" option tells rsync to modify all incoming
symlinks in a way that makes them unusable but recoverable (see
below). This should help protect your files from user trickery
when your daemon module is writable. The default is disabled
when "use chroot" is on and enabled when "use chroot" is off.
If you disable this option on a daemon that is not read-only,
there are tricks that a user can play with uploaded symlinks to
access daemon-excluded items (if your module has any), and, if
"use chroot" is off, rsync can even be tricked into showing or
changing data that is outside the module's path (as access-
permissions allow).
The way rsync disables the use of symlinks is to prefix each one
with the string "/rsyncd-munged/". This prevents the links from
being used as long as that directory does not exist. When this
option is enabled, rsync will refuse to run if that path is a
directory or a symlink to a directory. When using the "munge
symlinks" option in a chroot area, you should add this path to
the exclude setting for the module so that the user can't try to
create it.
Note: rsync makes no attempt to verify that any pre-existing
symlinks in the hierarchy are as safe as you want them to be.
If you setup an rsync daemon on a new area or locally add
symlinks, you can manually protect your symlinks from being
abused by prefixing "/rsyncd-munged/" to the start of every
symlink's value. There is a perl script in the support
directory of the source code named "munge-symlinks" that can be
used to add or remove this prefix from your symlinks.
When this option is disabled on a writable module and "use
chroot" is off, incoming symlinks will be modified to drop a
leading slash and to remove ".." path elements that rsync
believes will allow a symlink to escape the module's hierarchy.
There are tricky ways to work around this, though, so you had
better trust your users if you choose this combination of
options.
max connections
The "max connections" option allows you to specify the maximum
number of simultaneous connections you will allow. Any clients
connecting when the maximum has been reached will receive a
message telling them to try later. The default is 0 which means
no limit. See also the "lock file" option.
log file
When the "log file" option is set to a non-empty string, the
rsync daemon will log messages to the indicated file rather than
using syslog. This is particularly useful on systems (such as
AIX) where syslog() doesn't work for chrooted programs. The
file is opened before chroot() is called, allowing it to be
placed outside the transfer. If this value is set on a per-
module basis instead of globally, the global log will still
contain any authorization failures or config-file error
messages.
If the daemon fails to open to specified file, it will fall back
to using syslog and output an error about the failure. (Note
that the failure to open the specified log file used to be a
fatal error.)
syslog facility
The "syslog facility" option allows you to specify the syslog
facility name to use when logging messages from the rsync
daemon. You may use any standard syslog facility name which is
defined on your system. Common names are auth, authpriv, cron,
daemon, ftp, kern, lpr, mail, news, security, syslog, user,
uucp, local0, local1, local2, local3, local4, local5, local6 and
local7. The default is daemon. This setting has no effect if
the "log file" setting is a non-empty string (either set in the
per-modules settings, or inherited from the global settings).
max verbosity
The "max verbosity" option allows you to control the maximum
amount of verbose information that you'll allow the daemon to
generate (since the information goes into the log file). The
default is 1, which allows the client to request one level of
verbosity.
lock file
The "lock file" option specifies the file to use to support the
"max connections" option. The rsync daemon uses record locking
on this file to ensure that the max connections limit is not
exceeded for the modules sharing the lock file. The default is
/var/run/rsyncd.lock.
read only
The "read only" option determines whether clients will be able
to upload files or not. If "read only" is true then any
attempted uploads will fail. If "read only" is false then
uploads will be possible if file permissions on the daemon side
allow them. The default is for all modules to be read only.
write only
The "write only" option determines whether clients will be able
to download files or not. If "write only" is true then any
attempted downloads will fail. If "write only" is false then
downloads will be possible if file permissions on the daemon
side allow them. The default is for this option to be disabled.
list The "list" option determines if this module should be listed
when the client asks for a listing of available modules. By
setting this to false you can create hidden modules. The default
is for modules to be listable.
uid The "uid" option specifies the user name or user ID that file
transfers to and from that module should take place as when the
daemon was run as root. In combination with the "gid" option
this determines what file permissions are available. The default
is uid -2, which is normally the user "nobody".
gid The "gid" option specifies the group name or group ID that file
transfers to and from that module should take place as when the
daemon was run as root. This complements the "uid" option. The
default is gid -2, which is normally the group "nobody".
filter The "filter" option allows you to specify a space-separated list
of filter rules that the daemon will not allow to be read or
written. This is only superficially equivalent to the client
specifying these patterns with the --filter option. Only one
"filter" option may be specified, but it may contain as many
rules as you like, including merge-file rules. Note that per-
directory merge-file rules do not provide as much protection as
global rules, but they can be used to make --delete work better
when a client downloads the daemon's files (if the per-dir merge
files are included in the transfer).
exclude
The "exclude" option allows you to specify a space-separated
list of patterns that the daemon will not allow to be read or
written. This is only superficially equivalent to the client
specifying these patterns with the --exclude option. Only one
"exclude" option may be specified, but you can use "-" and "+"
before patterns to specify exclude/include.
Because this exclude list is not passed to the client it only
applies on the daemon: that is, it excludes files received by a
client when receiving from a daemon and files deleted on a
daemon when sending to a daemon, but it doesn't exclude files
from being deleted on a client when receiving from a daemon.
When you want to exclude a directory and all its contents, it is
safest to use a rule that does both, such as "/some/dir/***"
(the three stars tells rsync to exclude the directory itself and
everything inside it). This is better than just excluding the
directory alone with "/some/dir/", as it helps to guard against
attempts to trick rsync into accessing files deeper in the
hierarchy.
exclude from
The "exclude from" option specifies a filename on the daemon
that contains exclude patterns, one per line. This is only
superficially equivalent to the client specifying the
--exclude-from option with an equivalent file. See the
"exclude" option above.
include
The "include" option allows you to specify a space-separated
list of patterns which rsync should not exclude. This is only
superficially equivalent to the client specifying these patterns
with the --include option because it applies only on the daemon.
This is useful as it allows you to build up quite complex
exclude/include rules. Only one "include" option may be
specified, but you can use "+" and "-" before patterns to switch
include/exclude. See the "exclude" option above.
include from
The "include from" option specifies a filename on the daemon
that contains include patterns, one per line. This is only
superficially equivalent to the client specifying the
--include-from option with a equivalent file. See the "exclude"
option above.
incoming chmod
This option allows you to specify a set of comma-separated chmod
strings that will affect the permissions of all incoming files
(files that are being received by the daemon). These changes
happen after all other permission calculations, and this will
even override destination-default and/or existing permissions
when the client does not specify --perms. See the description
of the --chmod rsync option and the chmod(1) manpage for
information on the format of this string.
outgoing chmod
This option allows you to specify a set of comma-separated chmod
strings that will affect the permissions of all outgoing files
(files that are being sent out from the daemon). These changes
happen first, making the sent permissions appear to be different
than those stored in the filesystem itself. For instance, you
could disable group write permissions on the server while having
it appear to be on to the clients. See the description of the
--chmod rsync option and the chmod(1) manpage for information on
the format of this string.
auth users
The "auth users" option specifies a comma and space-separated
list of usernames that will be allowed to connect to this
module. The usernames do not need to exist on the local system.
The usernames may also contain shell wildcard characters. If
"auth users" is set then the client will be challenged to supply
a username and password to connect to the module. A challenge
response authentication protocol is used for this exchange. The
plain text usernames and passwords are stored in the file
specified by the "secrets file" option. The default is for all
users to be able to connect without a password (this is called
"anonymous rsync").
See also the "CONNECTING TO AN RSYNC DAEMON OVER A REMOTE SHELL
PROGRAM" section in rsync(1) for information on how handle an
rsyncd.conf-level username that differs from the remote-shell-
level username when using a remote shell to connect to an rsync
daemon.
secrets file
The "secrets file" option specifies the name of a file that
contains the username:password pairs used for authenticating
this module. This file is only consulted if the "auth users"
option is specified. The file is line based and contains
username:password pairs separated by a single colon. Any line
starting with a hash (#) is considered a comment and is skipped.
The passwords can contain any characters but be warned that many
operating systems limit the length of passwords that can be
typed at the client end, so you may find that passwords longer
than 8 characters don't work.
There is no default for the "secrets file" option, you must
choose a name (such as /etc/rsyncd.secrets). The file must
normally not be readable by "other"; see "strict modes".
strict modes
The "strict modes" option determines whether or not the
permissions on the secrets file will be checked. If "strict
modes" is true, then the secrets file must not be readable by
any user ID other than the one that the rsync daemon is running
under. If "strict modes" is false, the check is not performed.
The default is true. This option was added to accommodate rsync
running on the Windows operating system.
hosts allow
The "hosts allow" option allows you to specify a list of
patterns that are matched against a connecting clients hostname
and IP address. If none of the patterns match then the
connection is rejected.
Each pattern can be in one of five forms:
o a dotted decimal IPv4 address of the form a.b.c.d, or an
IPv6 address of the form a:b:c::d:e:f. In this case the
incoming machine's IP address must match exactly.
o an address/mask in the form ipaddr/n where ipaddr is the
IP address and n is the number of one bits in the
netmask. All IP addresses which match the masked IP
address will be allowed in.
o an address/mask in the form ipaddr/maskaddr where ipaddr
is the IP address and maskaddr is the netmask in dotted
decimal notation for IPv4, or similar for IPv6, e.g.
ffff:ffff:ffff:ffff:: instead of /64. All IP addresses
which match the masked IP address will be allowed in.
o a hostname. The hostname as determined by a reverse
lookup will be matched (case insensitive) against the
pattern. Only an exact match is allowed in.
o a hostname pattern using wildcards. These are matched
using the same rules as normal unix filename matching. If
the pattern matches then the client is allowed in.
Note IPv6 link-local addresses can have a scope in the address
specification:
fe80::1%link1
fe80::%link1/64
fe80::%link1/ffff:ffff:ffff:ffff::
You can also combine "hosts allow" with a separate "hosts deny"
option. If both options are specified then the "hosts allow"
option s checked first and a match results in the client being
able to connect. The "hosts deny" option is then checked and a
match means that the host is rejected. If the host does not
match either the "hosts allow" or the "hosts deny" patterns then
it is allowed to connect.
The default is no "hosts allow" option, which means all hosts
can connect.
hosts deny
The "hosts deny" option allows you to specify a list of patterns
that are matched against a connecting clients hostname and IP
address. If the pattern matches then the connection is rejected.
See the "hosts allow" option for more information.
The default is no "hosts deny" option, which means all hosts can
connect.
ignore errors
The "ignore errors" option tells rsyncd to ignore I/O errors on
the daemon when deciding whether to run the delete phase of the
transfer. Normally rsync skips the --delete step if any I/O
errors have occurred in order to prevent disastrous deletion due
to a temporary resource shortage or other I/O error. In some
cases this test is counter productive so you can use this option
to turn off this behavior.
ignore nonreadable
This tells the rsync daemon to completely ignore files that are
not readable by the user. This is useful for public archives
that may have some non-readable files among the directories, and
the sysadmin doesn't want those files to be seen at all.
transfer logging
The "transfer logging" option enables per-file logging of
downloads and uploads in a format somewhat similar to that used
by ftp daemons. The daemon always logs the transfer at the end,
so if a transfer is aborted, no mention will be made in the log
file.
If you want to customize the log lines, see the "log format"
option.
log format
The "log format" option allows you to specify the format used
for logging file transfers when transfer logging is enabled.
The format is a text string containing embedded single-character
escape sequences prefixed with a percent (%) character. An
optional numeric field width may also be specified between the
percent and the escape letter (e.g. "%-50n %8l %07p").
The default log format is "%o %h [%a] %m (%u) %f %l", and a "%t
[%p] " is always prefixed when using the "log file" option. (A
perl script that will summarize this default log format is
included in the rsync source code distribution in the "support"
subdirectory: rsyncstats.)
The single-character escapes that are understood are as follows:
o %a the remote IP address
o %b the number of bytes actually transferred
o %B the permission bits of the file (e.g. rwxrwxrwt)
o %c the checksum bytes received for this file (only when
sending)
o %f the filename (long form on sender; no trailing "/")
o %G the gid of the file (decimal) or "DEFAULT"
o %h the remote host name
o %i an itemized list of what is being updated
o %l the length of the file in bytes
o %L the string " -> SYMLINK", " => HARDLINK", or "" (where
SYMLINK or HARDLINK is a filename)
o %m the module name
o %M the last-modified time of the file
o %n the filename (short form; trailing "/" on dir)
o %o the operation, which is "send", "recv", or "del." (the
latter includes the trailing period)
o %p the process ID of this rsync session
o %P the module path
o %t the current date time
o %u the authenticated username or an empty string
o %U the uid of the file (decimal)
For a list of what the characters mean that are output by "%i",
see the --itemize-changes option in the rsync manpage.
Note that some of the logged output changes when talking with
older rsync versions. For instance, deleted files were only
output as verbose messages prior to rsync 2.6.4.
timeout
The "timeout" option allows you to override the clients choice
for I/O timeout for this module. Using this option you can
ensure that rsync won't wait on a dead client forever. The
timeout is specified in seconds. A value of zero means no
timeout and is the default. A good choice for anonymous rsync
daemons may be 600 (giving a 10 minute timeout).
refuse options
The "refuse options" option allows you to specify a space-
separated list of rsync command line options that will be
refused by your rsync daemon. You may specify the full option
name, its one-letter abbreviation, or a wild-card string that
matches multiple options. For example, this would refuse
--checksum (-c) and all the various delete options:
refuse options = c delete
The reason the above refuses all delete options is that the
options imply --delete, and implied options are refused just
like explicit options. As an additional safety feature, the
refusal of "delete" also refuses remove-sent-files when the
daemon is the sender; if you want the latter without the former,
instead refuse "delete-*" -- that refuses all the delete modes
without affecting --remove-sent-files.
When an option is refused, the daemon prints an error message
and exits. To prevent all compression when serving files, you
can use "dont compress = *" (see below) instead of "refuse
options = compress" to avoid returning an error to a client that
requests compression.
dont compress
The "dont compress" option allows you to select filenames based
on wildcard patterns that should not be compressed when pulling
files from the daemon (no analogous option exists to govern the
pushing of files to a daemon). Compression is expensive in
terms of CPU usage, so it is usually good to not try to compress
files that won't compress well, such as already compressed
files.
The "dont compress" option takes a space-separated list of case-
insensitive wildcard patterns. Any source filename matching one
of the patterns will not be compressed during transfer.
The default setting is *.gz *.tgz *.zip *.z *.rpm *.deb *.iso
*.bz2 *.tbz
pre-xfer exec, post-xfer exec
You may specify a command to be run before and/or after the
transfer. If the pre-xfer exec command fails, the transfer is
aborted before it begins.
The following environment variables will be set, though some are
specific to the pre-xfer or the post-xfer environment:
o RSYNC_MODULE_NAME: The name of the module being accessed.
o RSYNC_MODULE_PATH: The path configured for the module.
o RSYNC_HOST_ADDR: The accessing host's IP address.
o RSYNC_HOST_NAME: The accessing host's name.
o RSYNC_USER_NAME: The accessing user's name (empty if no
user).
o RSYNC_PID: A unique number for this transfer.
o RSYNC_REQUEST: (pre-xfer only) The module/path info
specified by the user (note that the user can specify
multiple source files, so the request can be something
like "mod/path1 mod/path2", etc.).
o RSYNC_ARG#: (pre-xfer only) The pre-request arguments are
set in these numbered values. RSYNC_ARG0 is always
"rsyncd", and the last value contains a single period.
o RSYNC_EXIT_STATUS: (post-xfer only) the server side's
exit value. This will be 0 for a successful run, a
positive value for an error that the server generated, or
a -1 if rsync failed to exit properly. Note that an
error that occurs on the client side does not currently
get sent to the server side, so this is not the final
exit status for the whole transfer.
o RSYNC_RAW_STATUS: (post-xfer only) the raw exit value
from waitpid() .
Even though the commands can be associated with a particular
module, they are run using the permissions of the user that
started the daemon (not the module's uid/gid setting) without
any chroot restrictions.
AUTHENTICATION STRENGTH
The authentication protocol used in rsync is a 128 bit MD4 based
challenge response system. This is fairly weak protection, though (with
at least one brute-force hash-finding algorithm publicly available), so
if you want really top-quality security, then I recommend that you run
rsync over ssh. (Yes, a future version of rsync will switch over to a
stronger hashing method.)
Also note that the rsync daemon protocol does not currently provide any
encryption of the data that is transferred over the connection. Only
authentication is provided. Use ssh as the transport if you want
encryption.
Future versions of rsync may support SSL for better authentication and
encryption, but that is still being investigated.
EXAMPLES
A simple rsyncd.conf file that allow anonymous rsync to a ftp area at
/home/ftp would be:
[ftp]
path = /home/ftp
comment = ftp export area
A more sophisticated example would be:
uid = nobody
gid = nobody
use chroot = no
max connections = 4
syslog facility = local5
pid file = /var/run/rsyncd.pid
[ftp]
path = /var/ftp/pub
comment = whole ftp area (approx 6.1 GB)
[sambaftp]
path = /var/ftp/pub/samba
comment = Samba ftp area (approx 300 MB)
[rsyncftp]
path = /var/ftp/pub/rsync
comment = rsync ftp area (approx 6 MB)
[sambawww]
path = /public_html/samba
comment = Samba WWW pages (approx 240 MB)
[cvs]
path = /data/cvs
comment = CVS repository (requires authentication)
auth users = tridge, susan
secrets file = /etc/rsyncd.secrets
The /etc/rsyncd.secrets file would look something like this:
tridge:mypass
susan:herpass
FILES
/etc/rsyncd.conf or rsyncd.conf
SEE ALSO
rsync(1)
DIAGNOSTICS
BUGS
Please report bugs! The rsync bug tracking system is online at
http://rsync.samba.org/
VERSION
This man page is current for version 2.6.9 of rsync.
CREDITS
rsync is distributed under the GNU public license. See the file
COPYING for details.
The primary ftp site for rsync is ftp://rsync.samba.org/pub/rsync.
A WEB site is available at http://rsync.samba.org/
We would be delighted to hear from you if you like this program.
This program uses the zlib compression library written by Jean-loup
Gailly and Mark Adler.
THANKS
Thanks to Warren Stanley for his original idea and patch for the rsync
daemon. Thanks to Karsten Thygesen for his many suggestions and
documentation!
AUTHOR
rsync was written by Andrew Tridgell and Paul Mackerras. Many people
have later contributed to it.
Mailing lists for support and development are available at
http://lists.samba.org
6 Nov 2006 rsyncd.conf(5)