rsyncd.conf(5) rsyncd.conf(5)

rsyncd.conf - configuration file for rsync in daemon mode

rsyncd.conf

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.

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.

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.

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.

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.
The "pid file" option tells the rsync daemon to write its process ID to that file.
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.
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.
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.

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.

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.
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.
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.
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.
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.
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.
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.)
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).
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.
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.
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.
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.
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.
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".
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".
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).
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.
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.
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.
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.
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.
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.
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.
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".
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.
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:
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.
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.
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.
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.
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.
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.
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.
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.
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.
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:
%a the remote IP address
%b the number of bytes actually transferred
%B the permission bits of the file (e.g. rwxrwxrwt)
%c the checksum bytes received for this file (only when sending)
%f the filename (long form on sender; no trailing "/")
%G the gid of the file (decimal) or "DEFAULT"
%h the remote host name
%i an itemized list of what is being updated
%l the length of the file in bytes
%L the string " -> SYMLINK", " => HARDLINK", or "" (where SYMLINK or HARDLINK is a filename)
%m the module name
%M the last-modified time of the file
%n the filename (short form; trailing "/" on dir)
%o the operation, which is "send", "recv", or "del." (the latter includes the trailing period)
%p the process ID of this rsync session
%P the module path
%t the current date time
%u the authenticated username or an empty string
%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.
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).
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.
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
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:
RSYNC_MODULE_NAME: The name of the module being accessed.
RSYNC_MODULE_PATH: The path configured for the module.
RSYNC_HOST_ADDR: The accessing host's IP address.
RSYNC_HOST_NAME: The accessing host's name.
RSYNC_USER_NAME: The accessing user's name (empty if no user).
RSYNC_PID: A unique number for this transfer.
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.).
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.
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.
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.

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.

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

/etc/rsyncd.conf or rsyncd.conf

rsync(1)

Please report bugs! The rsync bug tracking system is online at http://rsync.samba.org/

This man page is current for version 2.6.9 of rsync.

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 to Warren Stanley for his original idea and patch for the rsync daemon. Thanks to Karsten Thygesen for his many suggestions and documentation!

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