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.
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 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.
rsyncd.conf
.
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 "use chroot" is false or the inside-chroot path 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 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.
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.
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 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 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 (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 options.
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 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.)
/var/run/rsyncd.lock
.
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.
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.
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".
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 default is no "hosts deny" option, which means all hosts can connect.
If you want to customize the log lines, see the "log format" option.
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.
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-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" 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.
See the --skip-compress option in the rsync(1) manpage for the list of file suffixes that are not compressed by default. Specifying a value for the "dont compress" option 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", 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 = 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 3.0.0pre10 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