|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
rsyncd.conf(5) User Commands rsyncd.conf(5)
rsyncd.conf - configuration file for rsync in daemon mode
rsyncd.conf
The online version of this manpage (that includes cross-linking
of topics) is available at
⟨https://download.samba.org/pub/rsync/rsyncd.conf.5⟩.
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:
motd file
This parameter allows you to specify a "message of the
day" (MOTD) to display to clients on each connect. This
usually contains site information and any legal notices.
The default is no MOTD file. This can be overridden by
the --dparam=motdfile=FILE command-line option when
starting the daemon.
pid file
This parameter tells the rsync daemon to write its process
ID to that file. The rsync keeps the file locked so that
it can know when it is safe to overwrite an existing file.
The filename can be overridden by the
--dparam=pidfile=FILE command-line option when starting
the daemon.
port You can override the default port the daemon will listen
on by specifying this value (defaults to 873). This is
ignored if the daemon is being run by inetd, and is
superseded by the --port command-line option.
address
You can override the default IP address the daemon will
listen on by specifying this value. This is ignored if
the daemon is being run by inetd, and is superseded by the
--address command-line option.
socket options
This parameter 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 manpage 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 can also be specified via the --sockopts
command-line option.
listen backlog
You can override the default backlog value when the daemon
listens for connections. It defaults to 5.
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 first 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 %%.
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.
There is also a special module name of "[global]" that does not
define a module but instead switches back to the global settings
context where default parameters can be specified. Because each
defined module gets its full set of parameters as a combination
of the default values that are set at that position in the config
file plus its own parameter list, the use of a "[global]" section
can help to maintain shared config values for multiple modules.
As with GLOBAL PARAMETERS, you may use references to environment
variables in the values of parameters. See that section for
details.
comment
This parameter 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 This parameter specifies the directory in the daemon's
filesystem to make available in this module. You must
specify this parameter for each module in rsyncd.conf.
If the value contains a "/./" element then the path will
be divided at that point into a chroot dir and an inner-
chroot subdir. If use chroot is set to false, though, the
extraneous dot dir is just cleaned out of the path. An
example of this idiom is:
path = /var/rsync/./module1
This will (when chrooting) chroot to "/var/rsync" and set
the inside-chroot path to "/module1".
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.
use chroot
If "use chroot" is true, the rsync daemon will chroot to
the "path" before starting the file transfer with the
client. This has the advantage of extra protection
against possible implementation security holes, but it has
the disadvantages of requiring super-user privileges, of
not being able to follow symbolic links that are either
absolute or outside of the new root path, and of
complicating the preservation of users and groups by name
(see below).
If use chroot is not set, it defaults to trying to enable
a chroot but allows the daemon to continue (after logging
a warning) if it fails. The one exception to this is when
a module's path has a "/./" chroot divider in it -- this
causes an unset value to be treated as true for that
module.
Prior to rsync 3.2.7, the default value was "true". The
new "unset" default makes it easier to setup an rsync
daemon as a non-root user or to run a daemon on a system
where chroot fails. Explicitly setting the value to
"true" in rsyncd.conf will always require the chroot to
succeed.
It is also possible to specify a dot-dir in the module's
"path" to indicate that you want to chdir to the earlier
part of the path and then serve files from inside the
latter part of the path (with sanitizing and default
symlink munging). This can be useful if you need some
library dirs inside the chroot (typically for uid & gid
lookups) but don't want to put the lib dir into the top of
the served path (even though they can be hidden with an
exclude directive). However, a better choice for a modern
rsync setup is to use a name converter" and try to avoid
inner lib dirs altogether. See also the daemon chroot
parameter, which causes rsync to chroot into its own
chroot area before doing any path-related chrooting.
If the daemon is serving the "/" dir (either directly or
due to being chrooted to the module's path), rsync does
not do any path sanitizing or (default) munging.
When it has to limit access to a particular subdir (either
due to chroot being disabled or having an inside-chroot
path set), rsync will munge symlinks (by default) and
sanitize paths. Those that dislike munged symlinks (and
really, really trust their users to not break out of the
subdir) can disable the symlink munging via the "munge
symlinks" parameter.
When rsync is sanitizing paths, it trims ".." path
elements from args that it believes would escape the
module hierarchy. It also substitutes leading slashes in
absolute paths with the module's path (so that options
such as --backup-dir & --compare-dest interpret an
absolute path as rooted in the module's "path" dir).
When a chroot is in effect and the "name converter"
parameter is not set, the "numeric ids" parameter will
default to being enabled (disabling name lookups). This
means that if you manually setup name-lookup libraries in
your chroot (instead of using a name converter) that you
need to explicitly set numeric ids = false for rsync to do
name lookups.
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). However, it's easier and
safer to setup a name converter.
daemon chroot
This parameter specifies a path to which the daemon will
chroot before beginning communication with clients. Module
paths (and any "use chroot" settings) will then be related
to this one. This lets you choose if you want the whole
daemon to be chrooted (with this setting), just the
transfers to be chrooted (with "use chroot"), or both.
Keep in mind that the "daemon chroot" area may need
various OS/lib/etc files installed to allow the daemon to
function. By default the daemon runs without any
chrooting.
proxy protocol
When this parameter is enabled, all incoming connections
must start with a V1 or V2 proxy protocol header. If the
header is not found, the connection is closed.
Setting this to true requires a proxy server to forward
source IP information to rsync, allowing you to log proper
IP/host info and make use of client-oriented IP
restrictions. The default of false means that the IP
information comes directly from the socket's metadata. If
rsync is not behind a proxy, this should be disabled.
CAUTION: using this option can be dangerous if you do not
ensure that only the proxy is allowed to connect to the
rsync port. If any non-proxied connections are allowed
through, the client will be able to use a modified rsync
to spoof any remote IP address that they desire. You can
lock this down using something like iptables -uid-
owner root rules (for strict localhost access), various
firewall rules, or you can require password authorization
so that any spoofing by users will not grant extra access.
This setting is global. If you need some modules to
require this and not others, then you will need to setup
multiple rsync daemon processes on different ports.
name converter
This parameter lets you specify a program that will be run
by the rsync daemon to do user & group conversions between
names & ids. This script is started prior to any chroot
being setup, and runs as the daemon user (not the transfer
user). You can specify a fully qualified pathname or a
program name that is on the $PATH.
The program can be used to do normal user & group lookups
without having to put any extra files into the chroot area
of the module or you can do customized conversions.
The nameconvert program has access to all of the
environment variables that are described in the section on
pre-xfer exec. This is useful if you want to customize
the conversion using information about the module and/or
the copy request.
There is a sample python script in the support dir named
"nameconvert" that implements the normal user & group
lookups. Feel free to customize it or just use it as
documentation to implement your own.
numeric ids
Enabling this parameter 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. This enabling 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. Also keep in mind that uid/gid preservation
requires the module to be running as root (see "uid") or
for "fake super" to be configured.
A chroot-enabled module should not have this parameter set
to false unless you're using a "name converter" program or
you've taken steps to ensure that the module has the
necessary resources it needs to translate names and that
it is not possible for a user to change those resources.
munge symlinks
This parameter tells rsync to modify all symlinks in the
same way as the (non-daemon-affecting) --munge-links
command-line option (using a method described 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 with an inside-chroot
path of "/", OR if "daemon chroot" is on, otherwise it is
enabled.
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.
charset
This specifies the name of the character set in which the
module's filenames are stored. If the client uses an
--iconv option, the daemon will use the value of the
"charset" parameter regardless of the character set the
client actually passed. This allows the daemon to support
charset conversion in a chroot module without extra files
in the chroot area, and also ensures that name-translation
is done in a consistent manner. If the "charset"
parameter is not set, the --iconv option is refused, just
as if "iconv" had been specified via "refuse 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.
max connections
This parameter 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. A negative value disables the
module. See also the "lock file" parameter.
log file
When the "log file" parameter 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 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.
syslog facility
This parameter 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).
syslog tag
This parameter allows you to specify the syslog tag to use
when logging messages from the rsync daemon. The default
is "rsyncd". 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).
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%
max verbosity
This parameter 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.
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.
lock file
This parameter specifies the file to use to support the
"max connections" parameter. The rsync daemon uses record
locking on this file to ensure that the max connections
limit is not exceeded for the modules sharing the lock
file. The default is /var/run/rsyncd.lock.
read only
This parameter 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.
Note that "auth users" can override this setting on a per-
user basis.
write only
This parameter 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 parameter
to be disabled.
Helpful hint: you probably want to specify "refuse options
= delete" for a write-only module.
open noatime
When set to True, this parameter tells the rsync daemon to
open files with the O_NOATIME flag (on systems that
support it) to avoid changing the access time of the files
that are being transferred. If your OS does not support
the O_NOATIME flag then rsync will silently ignore this
option. Note also that some filesystems are mounted to
avoid updating the atime on read access even without the
O_NOATIME flag being set.
When set to False, this parameters ensures that files on
the server are not opened with O_NOATIME.
When set to Unset (the default) the user controls the
setting via --open-noatime.
list This parameter determines whether this module is listed
when the client asks for a listing of available modules.
In addition, if this is false, the daemon will pretend the
module does not exist when a client denied by "hosts
allow" or "hosts deny" attempts to access it. Realize
that if "reverse lookup" is disabled globally but enabled
for the module, the resulting reverse lookup to a
potentially client-controlled DNS server may still reveal
to the client that it hit an existing module. The default
is for modules to be listable.
uid This parameter 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" parameter this determines what file permissions
are available. The default when run by a super-user is to
switch to the system's "nobody" user. The default for a
non-super-user is to not try to change the user. See also
the "gid" parameter.
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 = *
gid This parameter specifies one or more group names/IDs that
will be used when accessing the module. The first one
will be the default group, and any extra ones be set as
supplemental groups. You may also specify a "*" as the
first gid in the list, which will be replaced by all the
normal groups for the transfer's user (see "uid"). The
default when run by a super-user is to switch to your OS's
"nobody" (or perhaps "nogroup") group with no other
supplementary groups. The default for a non-super-user is
to not change any group attributes (and indeed, your OS
may not allow a non-super-user to try to change their
group settings).
The specified list is normally split into tokens based on
spaces and commas. However, if the list starts with a
comma, then the list is only split on commas, which allows
a group name to contain a space. In either case any
leading and/or trailing whitespace is removed from the
tokens and empty tokens are ignored.
daemon uid
This parameter specifies a uid under which the daemon will
run. The daemon usually runs as user root, and when this
is left unset the user is left unchanged. See also the
"uid" parameter.
daemon gid
This parameter specifies a gid under which the daemon will
run. The daemon usually runs as group root, and when this
is left unset, the group is left unchanged. See also the
"gid" parameter.
fake super
Setting "fake super = yes" for a module causes the daemon
side to behave as if the --fake-super command-line option
had been specified. This allows the full attributes of a
file to be stored without having to have the daemon
actually running as root.
filter The daemon has its own filter chain that determines what
files it will let the client access. This chain is not
sent to the client and is independent of any filters the
client may have specified. Files excluded by the daemon
filter chain (daemon-excluded files) are treated as non-
existent if the client tries to pull them, are skipped
with an error message if the client tries to push them
(triggering exit code 23), and are never deleted from the
module. You can use daemon filters to prevent clients
from downloading or tampering with private administrative
files, such as files you may add to support uid/gid name
translations.
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.
exclude
This parameter takes a space-separated list of daemon
exclude patterns. As with the client --exclude option,
patterns can be qualified with "- " or "+ " to explicitly
indicate exclude/include. Only one "exclude" parameter
can apply to a given module. See the "filter" parameter
for a description of how excluded files affect the daemon.
include
Use an "include" to override the effects of the "exclude"
parameter. Only one "include" parameter can apply to a
given module. See the "filter" parameter for a
description of how excluded files affect the daemon.
exclude from
This parameter specifies the name of a file on the daemon
that contains daemon exclude patterns, one per line. Only
one "exclude from" parameter can apply to a given module;
if you have multiple exclude-from files, you can specify
them as a merge file in the "filter" parameter. See the
"filter" parameter for a description of how excluded files
affect the daemon.
include from
Analogue of "exclude from" for a file of daemon include
patterns. Only one "include from" parameter can apply to
a given module. See the "filter" parameter for a
description of how excluded files affect the daemon.
incoming chmod
This parameter allows you to specify a set of comma-
separated chmod strings that will affect the permissions
of all incoming files (files that are being received by
the daemon). These changes happen after all other
permission calculations, and this will even override
destination-default and/or existing permissions when the
client does not specify --perms. See the description of
the --chmod rsync option and the chmod(1) manpage for
information on the format of this string.
outgoing chmod
This parameter allows you to specify a set of comma-
separated chmod strings that will affect the permissions
of all outgoing files (files that are being sent out from
the daemon). These changes happen first, making the sent
permissions appear to be different than those stored in
the filesystem itself. For instance, you could disable
group write permissions on the server while having it
appear to be on to the clients. See the description of
the --chmod rsync option and the chmod(1) manpage for
information on the format of this string.
auth users
This parameter specifies a comma and/or space-separated
list of authorization rules. In its simplest form, you
list the usernames that will be allowed to connect to this
module. The usernames do not need to exist on the local
system. The rules may contain shell wildcard characters
that will be matched against the username provided by the
client for authentication. 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" parameter. The default is
for all users to be able to connect without a password
(this is called "anonymous rsync").
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.
secrets file
This parameter specifies the name of a file that contains
the username:password and/or @groupname:password pairs
used for authenticating this module. This file is only
consulted if the "auth users" parameter is specified. The
file is line-based and contains one name:password pair per
line. Any line has a hash (#) as the very first character
on the line 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.
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 an "auth users" module will be possible.
strict modes
This parameter 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 parameter was
added to accommodate rsync running on the Windows
operating system.
hosts allow
This parameter allows you to specify a list of comma-
and/or whitespace-separated patterns that are matched
against a connecting client's hostname and IP address. If
none of the patterns match, then the connection is
rejected.
Each pattern can be in one of six 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 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).
o 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.
o an '@' followed by a netgroup name, which will
match if the reverse DNS of the connecting IP is in
the specified netgroup.
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 "hosts deny" as a
way to add exceptions to your deny list. When both
parameters are specified, the "hosts allow" parameter is
checked first and a match results in the client being able
to connect. A non-allowed host is then matched against
the "hosts deny" list to see if it should be rejected. A
host that does not match either list is allowed to
connect.
The default is no "hosts allow" parameter, which means all
hosts can connect.
hosts deny
This parameter allows you to specify a list of comma-
and/or whitespace-separated 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" parameter for more information.
The default is no "hosts deny" parameter, which means all
hosts can connect.
reverse lookup
Controls whether the daemon performs a reverse lookup on
the client's IP address to determine its hostname, which
is used for "hosts allow" & "hosts deny" checks and the
"%h" log escape. This is enabled by default, but you may
wish to disable it to save time if you know the lookup
will not return a useful result, in which case the daemon
will use the name "UNDETERMINED" instead.
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.
forward lookup
Controls whether the daemon performs a forward lookup on
any hostname specified in an hosts allow/deny setting. By
default this is enabled, allowing the use of an explicit
hostname that would not be returned by reverse DNS of the
connecting IP.
ignore errors
This parameter 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 parameter to turn off this
behavior.
ignore nonreadable
This tells the rsync daemon to completely ignore files
that are not readable by the user. This is useful for
public archives that may have some non-readable files
among the directories, and the sysadmin doesn't want those
files to be seen at all.
transfer logging
This parameter 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" parameter.
log format
This parameter 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"). In addition, one or more apostrophes
may be specified prior to a numerical escape to indicate
that the numerical value should be made more human-
readable. The 3 supported levels are the same as for the
--human-readable command-line option, though the default
is for human-readability to be off. Each added apostrophe
increases the level (e.g. "%''l %'b %f").
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:
o %a the remote IP address (only available for a
daemon)
o %b the number of bytes actually transferred
o %B the permission bits of the file (e.g. rwxrwxrwt)
o %c the total size of the block checksums received
for the basis file (only when sending)
o %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.
o %f the filename (long form on sender; no trailing
"/")
o %G the gid of the file (decimal) or "DEFAULT"
o %h the remote host name (only available for a
daemon)
o %i an itemized list of what is being updated
o %l the length of the file in bytes
o %L the string " -> SYMLINK", " => HARDLINK", or ""
(where SYMLINK or HARDLINK is a filename)
o %m the module name
o %M the last-modified time of the file
o %n the filename (short form; trailing "/" on dir)
o %o the operation, which is "send", "recv", or
"del." (the latter includes the trailing period)
o %p the process ID of this rsync session
o %P the module path
o %t the current date time
o %u the authenticated username or an empty string
o %U the uid of the file (decimal)
For a list of what the characters mean that are output by
"%i", see the --itemize-changes option in the rsync
manpage.
Note that some of the logged output changes when talking
with older rsync versions. For instance, deleted files
were only output as verbose messages prior to rsync 2.6.4.
timeout
This parameter allows you to override the clients choice
for I/O timeout for this module. Using this parameter you
can ensure that rsync won't wait on a dead client forever.
The timeout is specified in seconds. A value of zero means
no timeout and is the default. A good choice for anonymous
rsync daemons may be 600 (giving a 10 minute timeout).
refuse options
This parameter 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. Beginning in 3.2.0, you can also
negate a match term by starting it with a "!".
When an option is refused, the daemon prints an error
message and exits.
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.
The use of a negated match allows you to fine-tune your
refusals after a wild-card, such as this:
refuse options = delete-* !delete-during
Negated matching can also turn your list of refused
options into a list of accepted options. To do this, begin
the list with a "*" (to refuse all options) and then
specify one or more negated matches to accept. For
example:
refuse options = * !a !v !compress*
Don't worry that the "*" will refuse certain vital options
such as --dry-run, --server, --no-iconv, --seclude-args,
etc. These important options are not matched by wild-card,
so they must be overridden by their exact name. For
instance, if you're forcing iconv transfers you could use
something like this:
refuse options = * no-iconv !a !v
As an additional aid (beginning in 3.2.0), refusing (or
"!refusing") the "a" or "archive" option also affects all
the options that the --archive option implies (-rdlptgoD),
but only if the option is matched explicitly (not using a
wildcard). If you want to do something tricky, you can use
"archive*" to avoid this side-effect, but keep in mind
that no normal rsync client ever sends the actual archive
option to the server.
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-*" as that refuses all the delete modes
without affecting --remove-source-files. (Keep in mind
that the client's --delete option typically results in
--delete-during.)
When un-refusing delete options, you should either specify
"!delete*" (to accept all delete options) or specify a
limited set that includes "delete", such as:
refuse options = * !a !delete !delete-during
... whereas this accepts any delete option except
--delete-after:
refuse options = * !a !delete* delete-after
A note on refusing "compress": it may be better to set the
"dont compress" daemon parameter to "*" and ensure that
RSYNC_COMPRESS_LIST=zlib is set in the environment of the
daemon in order to disable compression silently instead of
returning an error that forces the client to remove the -z
option.
If you are un-refusing the compress option, you may want
to match "!compress*" if you also want to allow the
--compress-level option.
Note that the "copy-devices" & "write-devices" options are
refused by default, but they can be explicitly accepted
with "!copy-devices" and/or "!write-devices". The options
"log-file" and "log-file-format" are forcibly refused and
cannot be accepted.
Here are all the options that are not matched by wild-
cards:
o --server: Required for rsync to even work.
o --rsh, -e: Required to convey compatibility flags
to the server.
o --out-format: This is required to convey output
behavior to a remote receiver. While rsync passes
the older alias --log-format for compatibility
reasons, this options should not be confused with
--log-file-format.
o --sender: Use "write only" parameter instead of
refusing this.
o --dry-run, -n: Who would want to disable this?
o --seclude-args, -s: Is the oldest arg-protection
method.
o --from0, -0: Makes it easier to accept/refuse
--files-from without affecting this helpful
modifier.
o --iconv: This is auto-disabled based on "charset"
parameter.
o --no-iconv: Most transfers use this option.
o --checksum-seed: Is a fairly rare, safe option.
o --write-devices: Is non-wild but also auto-
disabled.
dont compress
NOTE: This parameter currently has no effect except in one
instance: if it is set to "*" then it minimizes or
disables compression for all files (for those that don't
want to refuse the --compress option completely).
This parameter allows you to select filenames based on
wildcard patterns that should not be compressed when
pulling files from the daemon (no analogous parameter
exists to govern the pushing of files to a daemon).
Compression can be 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" parameter takes a space-separated list
of case-insensitive wildcard patterns. Any source filename
matching one of the patterns will be compressed as little
as possible during the transfer. If the compression
algorithm has an "off" level, then no compression occurs
for those files. If an algorithms has the ability to
change the level in mid-stream, it will be minimized to
reduce the CPU usage as much as possible.
See the --skip-compress parameter in the rsync(1) manpage
for the list of file suffixes that are skipped by default
if this parameter is not set.
early exec, pre-xfer exec, post-xfer exec
You may specify a command to be run in the early stages of
the connection, or right before and/or after the transfer.
If the early exec or pre-xfer exec command returns an
error code, the transfer is aborted before it begins. Any
output from the pre-xfer exec command on stdout (up to
several KB) will be displayed to the user when aborting,
but is not displayed if the script returns success. The
other programs cannot send any text to the user. All
output except for the pre-xfer exec stdout goes to the
corresponding daemon's stdout/stderr, which is typically
discarded. See the --no-detach option for a way to see
the daemon's output, which can assist with debugging.
Note that the early exec command runs before any part of
the transfer request is known except for the module name.
This helper script can be used to setup a disk mount or
decrypt some data into a module dir, but you may need to
use lock file and max connections to avoid concurrency
issues. If the client rsync specified the --early-
input=FILE option, it can send up to about 5K of data to
the stdin of the early script. The stdin will otherwise
be empty.
Note that the post-xfer exec command is still run even if
one of the other scripts returns an error code. The pre-
xfer exec command will not be run, however, if the
early exec command fails.
The following environment variables will be set, though
some are specific to the pre-xfer or the post-xfer
environment:
o RSYNC_MODULE_NAME: The name of the module being
accessed.
o RSYNC_MODULE_PATH: The path configured for the
module.
o RSYNC_HOST_ADDR: The accessing host's IP address.
o RSYNC_HOST_NAME: The accessing host's name.
o RSYNC_USER_NAME: The accessing user's name (empty
if no user).
o RSYNC_PID: A unique number for this transfer.
o RSYNC_REQUEST: (pre-xfer only) The module/path info
specified by the user. Note that the user can
specify multiple source files, so the request can
be something like "mod/path1 mod/path2", etc.
o RSYNC_ARG#: (pre-xfer only) The pre-request
arguments are set in these numbered values.
RSYNC_ARG0 is always "rsyncd", 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.
o RSYNC_EXIT_STATUS: (post-xfer only) the server
side's exit value. This will be 0 for a successful
run, a positive value for an error that the server
generated, or a -1 if rsync failed to exit
properly. Note that an error that occurs on the
client side does not currently get sent to the
server side, so this is not the final exit status
for the whole transfer.
o RSYNC_RAW_STATUS: (post-xfer only) the raw exit
value from waitpid().
Even though the commands can be associated with a
particular module, they are run using the permissions of
the user that started the daemon (not the module's uid/gid
setting) without any chroot restrictions.
These settings honor 2 environment variables: use
RSYNC_SHELL to set a shell to use when running the command
(which otherwise uses your system() call's default shell),
and use RSYNC_NO_XFER_EXEC to disable both options
completely.
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.
You can also make use of SSL/TLS encryption if you put rsync
behind an SSL proxy.
When setting up an rsync daemon for access via SSL/TLS, you will
need to configure a TCP proxy (such as haproxy or nginx) as the
front-end that handles the encryption.
o You should limit the access to the backend-rsyncd port to
only allow the proxy to connect. If it is on the same
host as the proxy, then configuring it to only listen on
localhost is a good idea.
o You should consider turning on the proxy protocol rsync-
daemon parameter if your proxy supports sending that
information. The examples below assume that this is
enabled.
An example haproxy setup is as follows:
frontend fe_rsync-ssl
bind :::874 ssl crt /etc/letsencrypt/example.com/combined.pem
mode tcp
use_backend be_rsync
backend be_rsync
mode tcp
server local-rsync 127.0.0.1:873 check send-proxy
An example nginx proxy setup is as follows:
stream {
server {
listen 874 ssl;
listen [::]:874 ssl;
ssl_certificate /etc/letsencrypt/example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/example.com/privkey.pem;
proxy_pass localhost:873;
proxy_protocol on; # Requires rsyncd.conf "proxy protocol = true"
proxy_timeout 1m;
proxy_connect_timeout 5s;
}
}
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), rsync-ssl(1)
Please report bugs! The rsync bug tracking system is online at
⟨https://rsync.samba.org/⟩.
This manpage is current for version 3.3.0 of rsync.
Rsync is distributed under the GNU General Public License. See
the file COPYING for details.
An rsync web site is available at ⟨https://rsync.samba.org/⟩ and
its github project is ⟨https://github.com/WayneD/rsync⟩.
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 originally written by Andrew Tridgell and Paul
Mackerras. Many people have later contributed to it. It is
currently maintained by Wayne Davison.
Mailing lists for support and development are available at
⟨https://lists.samba.org/⟩.
This page is part of the rsync (a fast, versatile, remote (and
local) file-copying tool) project. Information about the project
can be found at ⟨https://rsync.samba.org/⟩. If you have a bug
report for this manual page, see
⟨https://rsync.samba.org/bugzilla.html⟩. This page was obtained
from the tarball fetched from
⟨https://download.samba.org/pub/rsync/⟩ on 2024-06-14. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
rsyncd.conf from rsync 3.3.0 6 Apr 2024 rsyncd.conf(5)
Pages that refer to this page: rrsync(1), rsync(1), rsync-ssl(1)
|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|