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. (If a hash occurs after anything other than leading whitespace, it is considered a part of the line's content.)
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. Rsync also allows for the use of a "[global]" module name to indicate the start of one or more global-parameter sections (the name must be lower case).
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.
You may use references to environment variables in the values of parameters. String parameters will have %VAR% references expanded as late as possible (when the string is used in the program), allowing for the use of variables that rsync sets at connection time, such as RSYNC_USER_NAME. Non-string parameters (such as true/false settings) are expanded when read from the config file. If a variable does not exist in the environment, or if a sequence of characters is not a valid reference (such as an un-paired percent sign), the raw characters are passed through unchanged. This helps with backward compatibility and safety (e.g. expanding a non-existent %VAR% to an empty string in a path could result in a very unsafe path). The safest way to insert a literal % into a value is to use %%.
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 can also be specified
via the --sockopts command-line option.
After the global parameters 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 parameters for that module. The module name cannot contain a slash or a closing square bracket. If the name contains whitespace, each internal sequence of whitespace will be changed into a single space, while leading or trailing whitespace will be discarded. Also, the name cannot be "global" as that exact name indicates that global parameters follow (see above).
As with GLOBAL PARAMETERS, you may use references to environment variables in the values of parameters. See the GLOBAL PARAMETERS section for more details.
rsyncd.conf.
You may base the path's value off of an environment variable by surrounding the variable name with percent signs. You can even reference a variable that is set by rsync when the user connects. For example, this would use the authorizing user's name in the path:
path = /home/%RSYNC_USER_NAME%
It is fine if the path includes internal spaces -- they will be retained verbatim (which means that you shouldn't try to escape them). If your final directory has a trailing space (and this is somehow not something you wish to fix), append a trailing slash to the path to avoid losing the trailing whitespace.
As an additional safety feature, you can specify a dot-dir in the module's "path" to indicate the point where the chroot should occur. This allows rsync to run in a chroot with a non-"/" path for the top of the transfer hierarchy. Doing this guards against unintended library loading (since those absolute paths will not be inside the transfer hierarchy unless you have used an unwise pathname), and lets you setup libraries for the chroot that are outside of the transfer. For example, specifying "/var/rsync/./module1" will chroot to the "/var/rsync" directory and set the inside-chroot path to "/module1". If you had omitted the dot-dir, the chroot would have used the whole path, and the inside-chroot path would have been "/".
When both "use chroot" and "daemon chroot" are false, OR the inside-chroot path of "use chroot" is not "/", 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 module hierarchy. The default for "use chroot" is true, and is the safer choice (especially if the module is not read-only).
When this parameter is enabled, the "numeric-ids" option will also default to being enabled (disabling name lookups). See below for what a chroot needs in order for name lookups to succeed.
If you copy library 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 parameter). At that point it will be safe to enable the mapping of users and groups by name using the "numeric ids" daemon parameter (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.
A chroot-enabled module should not have this parameter 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. That includes being the code being able to call functions like
getpwuid()
,
getgrgid()
,
getpwname()
, and
getgrnam()
.
You should test what libraries and config files are required for your OS
and get those setup before starting to test name mapping in rsync.
If you disable this parameter 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 parameter is enabled, rsync will refuse to run if that path is a directory or a symlink to a directory. When using the "munge symlinks" parameter in a chroot area that has an inside-chroot path of "/", you should add "/rsyncd-munged/" to the exclude setting for the module so that a user can't try to create it.
Note: rsync makes no attempt to verify that any pre-existing symlinks in the module's hierarchy are as safe as you want them to be (unless, of course, it just copied in the whole hierarchy). 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 parameter is disabled on a writable module and "use chroot" is off (or the inside-chroot path is not "/"), 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 parameters.
If you wish to force users to always use --iconv for a particular module, add "no-iconv" to the "refuse options" parameter. Keep in mind that this will restrict access to your module to very new rsync clients.
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 the 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.)
This setting can be overridden by using the --log-file=FILE or --dparam=logfile=FILE command-line options. The former overrides all the log-file parameters of the daemon and all module settings. The latter sets the daemon's log file and the default for all the modules, which still allows modules to override the default setting.
For example, if you wanted each authenticated user's name to be included in the syslog tag, you could do something like this:
syslog tag = rsyncd.%RSYNC_USER_NAME%
This also affects the user's ability to request higher levels of --info and --debug logging. If the max value is 2, then no info and/or debug value that is higher than what would be set by -vv will be honored by the daemon in its logging. To see how high of a verbosity level you need to accept for a particular info/debug level, refer to "rsync --info=help" and "rsync --debug=help". For instance, it takes max-verbosity 4 to be able to output debug TIME2 and FLIST3.
/var/run/rsyncd.lock.
Note that "auth users" can override this setting on a per-user basis.
Helpful hint: you probably want to specify "refuse options = delete" for a write-only module.
The RSYNC_USER_NAME environment variable may be used to request that rsync run as the authorizing user. For example, if you want a rsync to run as the same user that was received for the rsync authentication, this setup is useful:
uid = %RSYNC_USER_NAME%
gid = *
The daemon filter chain is built from the "filter", "include from", "include", "exclude from", and "exclude" parameters, in that order of priority. Anchored patterns are anchored at the root of the module. To prevent access to an entire subtree, for example, "/secret", you must exclude everything in the subtree; the easiest way to do this is with a triple-star pattern like "/secret/***".
The "filter" parameter takes a space-separated list of daemon filter rules, though it is smart enough to know not to split a token at an internal space in a rule (e.g. "- /foo - /bar" is parsed as two rules). You may specify one or more merge-file rules using the normal syntax. Only one "filter" parameter can apply to a given module in the config file, so put all the rules you want in a single parameter. 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 during a client download operation if the per-dir merge files are included in the transfer and the client requests that they be used.
In addition to username matching, you can specify groupname matching via a '@' prefix. When using groupname matching, the authenticating username must be a real user on the system, or it will be assumed to be a member of no groups. For example, specifying "@rsync" will match the authenticating user if the named user is a member of the rsync group.
Finally, options may be specified after a colon (:). The options allow you to "deny" a user or a group, set the access to "ro" (read-only), or set the access to "rw" (read/write). Setting an auth-rule-specific ro/rw setting overrides the module's "read only" setting.
Be sure to put the rules in the order you want them to be matched, because the checking stops at the first matching user or group, and that is the only auth that is checked. For example:
auth users = joe:deny @guest:deny admin:rw @rsync:ro susan joe sam
In the above rule, user joe will be denied access no matter what. Any user that is in the group "guest" is also denied access. The user "admin" gets access in read/write mode, but only if the admin user is not in group "guest" (because the admin user-matching rule would never be reached if the user is in group "guest"). Any other user who is in group "rsync" will get read-only access. Finally, users susan, joe, and sam get the ro/rw setting of the module, but only if the user didn't match an earlier group-matching rule.
If you need to specify a user or group name with a space in it, start your list with a comma to indicate that the list should only be split on commas (though leading and trailing whitespace will also be removed, and empty entries are just ignored). For example:
auth users = , joe:deny, @Some Group:deny, admin:rw, @RO Group:ro
See the description of the secrets file for how you can have per-user passwords as well as per-group passwords. It also explains how a user can authenticate using their user password or (when applicable) a group password, depending on what rule is being authenticated.
See also the section entitled "USING RSYNC-DAEMON FEATURES VIA A REMOTE SHELL CONNECTION" 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 use of group-specific lines are only relevant when the module is being authorized using a matching "@groupname" rule. When that happens, the user can be authorized via either their "username:password" line or the "@groupname:password" line for the group that triggered the authentication.
It is up to you what kind of password entries you want to include, either users, groups, or both. The use of group rules in "auth users" does not require that you specify a group password if you do not want to use shared passwords.
There is no default for the "secrets file" parameter, you must choose a name
(such as /etc/rsyncd.secrets). The file must normally not be readable
by "other"; see "strict modes". If the file is not found or is rejected, no
logins for a "user auth" module will be possible.
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 pattern using wildcards. If the hostname of the connecting IP (as determined by a reverse lookup) matches the wildcarded name (using the same rules as normal unix filename matching), the client is allowed in. This only works if "reverse lookup" is enabled (the default).
- a hostname. A plain hostname is matched against the reverse DNS of the connecting IP (if "reverse lookup" is enabled), and/or the IP of the given hostname is matched against the connecting IP (if "forward lookup" is enabled, as it is by default). Any match will be 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" parameter. If both parameters are specified then the "hosts allow" parameter is checked first and a match results in the client being able to connect. The "hosts deny" parameter 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" parameter, which means all hosts can connect.
The default is no "hosts deny" parameter, which means all hosts can connect.
If this parameter is enabled globally (even by default), rsync performs the lookup as soon as a client connects, so disabling it for a module will not avoid the lookup. Thus, you probably want to disable it globally and then enable it for modules that need the information.
If you want to customize the log lines, see the "log format" parameter.
The default log format is "%o %h [%a] %m (%u) %f %l", and a "%t [%p] " is always prefixed when using the "log file" parameter. (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 (only available for a daemon)
- %b the number of bytes actually transferred
- %B the permission bits of the file (e.g. rwxrwxrwt)
- %c the total size of the block checksums received for the basis file (only when sending)
- %C the full-file checksum if it is known for the file. For older rsync protocols/versions, the checksum was salted, and is thus not a useful value (and is not displayed when that is the case). For the checksum to output for a file, either the --checksum option must be in-effect or the file must have been transferred without a salted checksum being used. See the --checksum-choice option for a way to choose the algorithm.
- %f the filename (long form on sender; no trailing "/")
- %G the gid of the file (decimal) or "DEFAULT"
- %h the remote host name (only available for a daemon)
- %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.
refuse options = c deleteThe 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-source-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-source-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" parameter takes a space-separated list of case-insensitive wildcard patterns. Any source filename matching one of the patterns will not be compressed during transfer.
See the --skip-compress parameter in the rsync(1) manpage for the list of file suffixes that are not compressed by default. Specifying a value for the "dont compress" parameter changes the default when the daemon is the sender.
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", followed by the options that were used in RSYNC_ARG1, and so on. There will be a value of "." indicating that the options are done and the path args are beginning -- these contain similar information to RSYNC_REQUEST, but with values separated and the module name stripped off.
- 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.
There are currently two config directives available that allow a config file to incorporate the contents of other files: &include and &merge. Both allow a reference to either a file or a directory. They differ in how segregated the file's contents are considered to be.
The &include directive treats each file as more distinct, with each one inheriting the defaults of the parent file, starting the parameter parsing as globals/defaults, and leaving the defaults unchanged for the parsing of the rest of the parent file.
The &merge directive, on the other hand, treats the file's contents as if it were simply inserted in place of the directive, and thus it can set parameters in a module started in another file, can affect the defaults for other files, etc.
When an &include or &merge directive refers to a directory, it will read in all the *.conf or *.inc files (respectively) that are contained inside that directory (without any recursive scanning), with the files sorted into alpha order. So, if you have a directory named "rsyncd.d" with the files "foo.conf", "bar.conf", and "baz.conf" inside it, this directive:
&include /path/rsyncd.d
would be the same as this set of directives:
&include /path/rsyncd.d/bar.conf
&include /path/rsyncd.d/baz.conf
&include /path/rsyncd.d/foo.conf
except that it adjusts as files are added and removed from the directory.
The advantage of the &include directive is that you can define one or more modules in a separate file without worrying about unintended side-effects between the self-contained module files.
The advantage of the &merge directive is that you can load config snippets that can be included into multiple module definitions, and you can also set global values that will affect connections (such as motd file), or globals that will affect other include files.
For example, this is a useful /etc/rsyncd.conf file:
port = 873
log file = /var/log/rsync.log
pid file = /var/lock/rsync.lock
&merge /etc/rsyncd.d
&include /etc/rsyncd.d
This would merge any /etc/rsyncd.d/*.inc files (for global values that should stay in effect), and then include any /etc/rsyncd.d/*.conf files (defining modules without any global-value cross-talk).
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 = yes
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 3.1.3 of rsync.
rsync is distributed under the GNU General 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