rsyncd(5) -- Linux man page

 

NAME

rsyncd.conf - configuration file for rsync server  

SYNOPSIS

rsyncd.conf

 

DESCRIPTION

The rsyncd.conf file is the runtime configuration file for rsync when run as an rsync server.

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. If run from an rsync client via a remote shell (by specifying both the "-e/--rsh" option and server mode with "::" or "rsync://"), the --daemon option is automatically passed to the remote side.

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 server 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.
log file
The "log file" option tells the rsync daemon to log messages to that file rather than using syslog. This is particularly useful on systems (such as AIX) where syslog() doesn't work for chrooted programs.
pid file
The "pid file" option tells the rsync daemon to write its process ID to that file.
syslog facility
The "syslog facility" option allows you to specify the syslog facility name to use when logging messages from the rsync server. 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.
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.

 

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 servers 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 server 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 usernames and groups (see below). When "use chroot" is false, for security reasons, symlinks may only be relative paths pointing to other files within the root path, and leading slashes are removed from most absolute paths (options such as --backup-dir, --compare-dest, etc. interpret an absolute path as rooted in the module's "path" dir, just as if chroot was specified). The default for "use chroot" is true.
In order to preserve usernames and groupnames, 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 a process in the chroot namespace will need to have access to the resources used by these library functions (traditionally /etc/passwd and /etc/group). If these resources are not available, rsync will only be able to copy the IDs, just as if the --numeric-ids option had been specified.
Note that you are free to setup user/group information in the chroot area differently from your normal system. For example, you could abbreviate the list of users and groups. Also, you can protect this information from being downloaded/uploaded by adding an exclude rule to the rsync.conf file (e.g. "exclude = /etc/"). Note that having the exclusion affect uploads is a relatively new feature in rsync, so make sure your server is running at least 2.6.3 to effect this.
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.
lock file
The "lock file" option specifies the file to use to support the "max connections" option. The rsync server 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 server 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 server 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".
exclude
The "exclude" option allows you to specify a space-separated list of patterns that the server 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 server: that is, it excludes files received by a client when receiving from a server and files deleted on a server when sending to a server, but it doesn't exclude files from being deleted on a client when receiving from a server.
exclude from
The "exclude from" option specifies a filename on the server 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 server. 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 server 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.
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 are 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 SERVER 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 server.
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 server 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 disasterous 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 behaviour.
ignore nonreadable
This tells the rsync server 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. If you want to customize the log formats look at 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.
The prefixes that are understood are:
o
%h for the remote host name
o
%a for the remote IP address
o
%l for the length of the file in bytes
o
%p for the process ID of this rsync session
o
%o for the operation, which is either "send" or "recv"
o
%f for the filename
o
%P for the module path
o
%m for the module name
o
%t for the current date time
o
%u for the authenticated username (or the null string)
o
%b for the number of bytes actually transferred
o
%c when sending files this gives the number of checksum bytes received for this file
The default log format is "%o %h [%a] %m (%u) %f %l", and a "%t [%p] " is always added to the beginning when using the "log file" option.
A perl script called rsyncstats to summarize this format is included in the rsync source code distribution.
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 servers 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 server. 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 options that start with "delete":
refuse options = c delete*
When an option is refused, the server prints an error message and exits. To prevent all compression, 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 during transfer. 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

 

 

AUTHENTICATION STRENGTH

The authentication protocol used in rsync is a 128 bit MD4 based challenge response system. Although I believe that no one has ever demonstrated a brute-force break of this sort of system you should realize that this is not a "military strength" authentication system. It should be good enough for most purposes but if you want really top quality security then I recommend that you run rsync over ssh.

Also note that the rsync server 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.

 

RUNNING AN RSYNC SERVER OVER A REMOTE SHELL PROGRAM

If rsync is run with both the --daemon and --rsh (-e) options, it will spawn an rsync daemon using a remote shell connection. Several configuration options will not be available unless the remote user is root (e.g. chroot, setuid/setgid, etc.). There is no need to configure inetd or the services map to include the rsync server port if you run an rsync server only via a remote shell program.

ADVANCED: To run an rsync server out of a single-use ssh key, use the "command=COMMAND" syntax in the remote user's authorized_keys entry, where command would be

rsync --server --daemon .

NOTE: rsync's argument parsing expects the trailing ".", so make sure that it's there. If you want to use an rsyncd.conf(5)-style configuration file other than the default, you can added a --config option to the command:

rsync --server --daemon --config=file .

Note that the "--server" here is the internal option that rsync uses to run the remote version of rsync that it communicates with, and thus you should not be using the --server option under normal circumstances.

 

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

The rsync server does not send all types of error messages to the client. this means a client may be mystified as to why a transfer failed. The error will have been logged by syslog on the server.

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

 

VERSION

This man page is current for version 2.x 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 server. Thanks to Karsten Thygesen for his many suggestions and documentation!

 

AUTHOR

rsync was written by Andrew Tridgell and Paul Mackerras. They may be contacted via email at tridge@samba.org and Paul.Mackerras@cs.anu.edu.au