rsyncd.conf - configuration file for rsync in daemon mode
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.
Systems using systemd can use the example unit files in the source
tree's packaging/systemd directory. The rsync.service file
runs a stand-alone daemon using
rsync --daemon --no-detach, while rsync.socket
and rsync@.service show a socket-activated setup for incoming
connections. These files may need local adjustment to match your installed
rsync path, packaging layout, and module policy.
When run via inetd you should add a line like this to
/etc/services:
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.
- 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 can disable the symlink munging via the "munge
symlinks" parameter; incoming symlink values are then sanitized
instead (see that parameter).
- When rsync is sanitizing paths, it resolves away the ".." path
elements that would take an arg above the module hierarchy. For an
operator-supplied option path such as --backup-dir &
--compare-dest, a leading slash is also substituted with the
module's path (so an absolute path is interpreted as rooted in the
module's "path" dir); for the transfer's own source args a
leading slash is simply dropped.
- 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.
- proxy protocol hosts
- This global parameter lists the socket peer IP addresses that are allowed
to supply a proxy protocol header. The syntax is the same
token format used by hosts allow. When
proxy protocol = true, this list must match
the direct peer before rsync trusts the forwarded client address.
- 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 incoming symlinks the same way as
the (non-daemon-affecting) --munge-links command-line option: it
prefixes each stored symlink's value with the string
"/rsyncd-munged/". Because that directory does not normally
exist, a munged symlink cannot be followed, so an uploaded symlink cannot
be used to read or write a file through it. On the way back out the prefix
is stripped, so clients see the original symlink values. When this
parameter is enabled, rsync refuses to run a module if
"/rsyncd-munged/" already exists in it as a directory or a
symlink to a directory. The default depends on chroot. For a plain
chrooted module -- "use chroot" on and "path"
with no "/./" split, so the daemon chroots straight into the
module and serves it as the chroot root -- munging is disabled by
default, since the chroot itself already stops a symlink from escaping. In
every other case it is enabled: any non-chroot module, or a chroot module
whose "path" uses a "/./" split to serve an inner
subdir below the chroot root.
- When this parameter is disabled on a writable module whose access is
limited to a subdir (i.e. "use chroot" is off, or the
inside-chroot path is not "/"), an incoming symlink is not
prefixed but is still sanitized as it is stored: a leading slash is
dropped and any leading ".." components that would take the
value above the module are removed, so a stored symlink's value cannot
name a path outside the module (it can still point to another name inside
the module).
- Munging changes only the symlink VALUES that are stored. Whether the
daemon follows a pre-existing in-module symlink when it resolves a
transfer path is a separate matter, governed by the secure path resolver
that is on by default; see the "insecure links" parameter for
the exact rule and how to opt out of it.
- 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.
- To add or remove the "/rsyncd-munged/" prefix on symlinks
yourself (for instance on links you create locally inside a module), there
is a python script in the support directory of the source code named
"munge-symlinks".
- insecure links
- This parameter (defaulting to "false") controls whether the
daemon resolves its symlink-bearing paths with the normal symlink-race
defences or with the legacy follow-any-symlink behaviour.
- When false (the default), the daemon refuses to follow a symlink it did
not create -- the directory enumeration and file-content opens of
the served module, and the operator-supplied paths (--backup-dir,
--temp-dir, --partial-dir, the alt-dest basis dirs, and so
on) are all resolved with a walk that follows a symlink component only
when it is owned by uid 0 or by the uid the module runs as,
refusing one planted by any other user. A client can never relax this: a
client that sends --insecure-links to the daemon has its request
refused.
- Setting this parameter to "true" restores the pre-hardening
behaviour for this module only: the daemon follows any
symlink in those paths.
- WARNING: enabling "insecure links" re-opens the
symlink-escape / TOCTOU vulnerabilities that the default closes (including
CVE-2026-53797 and CVE-2026-53801): an attacker who can create a symlink
inside the module -- or who shares the host with the served
tree -- can redirect the daemon's reads and writes to files
outside the module. Enable it only on a single-tenant,
fully-isolated, or otherwise trusted host where no untrusted local user
can plant a symlink in the served tree. It is the daemon analogue of the
client's --insecure-links and exists for the same narrow "I
accept the risk in my isolated environment" case.
- 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 chain matches the logical name of each item relative to
the module root, not the physical file it resolves to. It is a visibility
and tamper filter, not a security boundary against symlinks: a
symlink inside the module whose own name is not excluded can still be
followed to an excluded target (the name the filter sees -- e.g.
"link" -- is not the excluded name -- e.g.
"secret"). What protects a writable module from symlink
trickery is the "munge symlinks" parameter (enabled by default
for a writable, non-chrooted module), not this filter; do not rely
on exclude/filter to confine a peer who can introduce or
traverse a symlink.
- 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). Unless "strict
modes" is disabled, the file must not be readable or writable by
"other", and (when the daemon runs as root) must be owned by
root; see "strict modes" for the exact check. If the file is not
found or is rejected, no logins for an "auth users" module will
be possible.
- auth digest
- This parameter sets the minimum message digest that the daemon will
accept for the challenge-response authentication of an "auth
users" module. The available digests, strongest first, are
sha512, sha256, sha1, md5, md4. The
daemon selects its own most-preferred digest that also appears in the
connecting client's advertised list (and falls back to md5, or
md4 below protocol 30, for a client that advertises none), so a
client that advertises only weak digests can still force a weak negotiated
digest. If it is weaker than the configured name, the connection is
refused before the challenge is sent. The value is a single digest name,
for example:
- which requires sha256 or sha512 and refuses an md5 or
md4 exchange.
- This guards against an auth-digest downgrade. A peer that sends no
digest list (any rsync before 3.2.0, including the openrsync that ships
with macOS) makes the daemon fall back to md5 (or md4 below
protocol 30), and an on-path attacker can rewrite the unauthenticated
negotiation to force the same weak choice. A captured challenge-response
is far cheaper to brute-force offline against a weak digest, so a site
whose clients are all modern can require a strong one. See the rsync
SECURITY.md document for the full threat model.
- There is no default -- the floor is off and the daemon
accepts whatever digest is negotiated, preserving compatibility with older
clients. Enabling a floor refuses every client that cannot offer at least
that digest, notably any rsync older than 3.2.0 (when the SHA digests were
added) and the macOS-bundled openrsync, which authenticate only with
md4/md5. The SHA digests require an rsync built with openssl
at both ends; naming a digest this build does not provide refuses all
logins to the module (fail-closed).
- Like the other auth parameters, this may be set per module or, for a
default that applies to every module, in the global part of the config
file.
- strict modes
- This parameter determines whether or not the permissions on the secrets
file will be checked. If "strict modes" is true (the default),
the secrets file is rejected if it is readable or writable by
"other" (i.e. if any of the other-read or other-write permission
bits is set), and, when the daemon is running as root, if the file is not
owned by root. Group permissions and the other-execute bit are not
consulted, so modes such as 600 or 640 are accepted while 644 (or any
other-readable/-writable mode) is rejected. If "strict modes" is
false, no permission check is performed. 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().
- A %VAR% reference expanded into one of these commands is escaped
for the quoting context it appears in, which is correct for the single
shell that runs the command. It is not correct for a command that starts a
SECOND shell, such as
sh -c '... %RSYNC_USER_NAME% ...': the
outer shell consumes the escaping, and the inner one sees the value bare.
A value of touc? would then be glob-expanded against
/usr/bin/, so the substitution is not data any more -- it
chooses the command.
- Because rsync cannot escape for an unknown number of shell passes, a value
carrying any character that a shell could act on is refused outright, and
the transfer is aborted with
-
refusing to run shell hook: %VAR% holds a shell metacharacter
- The refused characters are whitespace, the quoting and expansion
characters ' " ` $ \, the
separators ; & |, redirections <
>, parentheses, the pattern characters * ?
[ ], #, !, ~, { }, and
any control character. Some of those are harmless on their own and are
refused for what a second shell would do with them --
! negates in command position, so a hook written as an access check
can be turned from a denial into an approval, and ~ is
tilde-expanded.
- This applies to EVERY %RSYNC_*% value, including ones you supplied
yourself. In particular a module whose path contains any of them
cannot be interpolated into one of these commands:
path = /srv/My Backups with a command
mentioning %RSYNC_MODULE_PATH% will refuse every transfer of that
module, not just a hostile one. The restriction is deliberate --
rsync cannot tell your space from an attacker's once both are inside the
same string, and path itself may be built from a peer value such as
path = /home/%RSYNC_USER_NAME%.
- If you need such a value in a hook, pass it through the environment
instead of interpolating it: the same names are exported to the command,
so "$RSYNC_MODULE_PATH" inside your script is
unrestricted by this check. Quote it there as shown -- rsync no
longer has any say in how your script splits the value.
- 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.
- temp dir
- Specifies a directory that rsync should use for temporary files created
during the transfer of updated files. If that directory is on a different
partition, after transfer file is being copied instead of unlinked.
- This parameter equals with --temp-dir option, so please consult
rsync manpage for further information.
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:
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).
An rsync daemon exposes part of your filesystem to network
clients, and its master process usually runs as root, so it should be
configured defensively. The following is a practical checklist; the
project's SECURITY.md describes the underlying threat model and the
per-platform residuals.
- Confine each module
to its path.
- Leave "use chroot" enabled (the default attempts a chroot) so
the per-connection worker is jailed inside the module's "path".
Where chroot is unavailable rsync still resolves every transfer path so it
cannot escape the module through a symlinked parent, but a chroot is the
stronger boundary -- keep it on unless you have a specific reason
not to. A path = /outer/./inner chroots to
/outer while serving /inner as the module root."
- Drop
privileges.
- Give each module a low-privilege "uid" and "gid" so a
worker never serves files as root; only the master process needs root (to
chroot and bind the port). Keep modules "read only" unless they
must accept uploads, and prefer "numeric ids" (or a "name
converter") so a malicious file list cannot map files to an
unexpected local owner."
- Restrict who can
connect.
- Limit reachability with "hosts allow" / "hosts deny",
bind the daemon to a specific "address", and use a host
firewall. A module without "auth users" is reachable by anyone
who can reach the port."
- Authenticate
with a strong secret and digest.
- Require login with "auth users" plus a "secrets file"
that is readable only by the daemon user (rsync refuses a too-open file
unless "strict modes" is disabled), and use a long, high-entropy
secret. To refuse the weak MD4/MD5 challenge digests that old clients can
negotiate, set a floor with "auth digest" (for example
auth digest = sha512); see the AUTHENTICATION
STRENGTH section below."
- Encrypt the
connection.
- The daemon protocol authenticates but does not encrypt the data
stream. Do not expose a cleartext daemon to an untrusted network: front it
with a TLS proxy (see the SSL/TLS Daemon Setup section below) or run it
over ssh."
- Keep symlink handling
safe.
- Leave "munge symlinks" enabled on any writable module (it is the
default) so an uploaded symlink cannot redirect a later operation outside
the module. Do not set "insecure links = yes" on a host
shared with untrusted local users: it disables the daemon's symlink-escape
protections (re-opening the symlink TOCTOU/escape vulnerabilities,
including CVE-2026-53797 and CVE-2026-53801) and is appropriate only on a
single-tenant, fully isolated host."
- Refuse options you do
not want.
- Use "refuse options" to reject client options a module should
not allow."
Daemon authentication is a challenge-response system in which the
client returns a digest of the shared secret and a server-chosen challenge.
Modern rsync (3.2.7 and later, built with openssl) negotiates the strongest
digest both sides support -- sha512 by default -- but
for backward compatibility it falls back to md5 (or md4 below
protocol 30) for a client that advertises no digest list, and the digest
negotiation is itself unauthenticated. A daemon that wants to require a
strong digest can set "auth digest". For the best protection, run
rsync over ssh or a verified TLS transport (rsync-ssl), which
protects the exchange at the transport layer, and use a high-entropy shared
secret (which is infeasible to brute-force regardless of the digest).
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;
}
}
If rsyncd should be accessible encrypted and unencrypted at the
same time make the proxy listen on port 873 as well and let it handle both
streams.
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
This manpage is current for version 3.5.0 of 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 from around the world have helped to maintain and
improve it.
Special thanks go to Wayne Davison, who maintained rsync from 2004
to 2024.
Mailing lists for support and development are available at
https://lists.samba.org/.