rsyncd.conf(5) - Man pages

rsyncd.conf(5) User Commands rsyncd.conf(5)

NAME
rsyncd.conf - configuration file for rsync in daemon mode

SYNOPSIS
rsyncd.conf

The online version of this manpage (that includes cross-linking of top-
ics) is available at ]8;;https://download.samba.org/pub/rsync/rsyncd.conf.5\https://download.samba.org/pub/rsync/rsyncd.conf.5]8;;\.

DESCRIPTION
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 avail-
able modules.

FILE FORMAT
The file consists of modules and parameters. A module begins with the
name of the module in square brackets and continues until the next mod-
ule begins. Modules contain parameters of the form name = value.

The file is line-based -- that is, each newline-terminated line repre-
sents either a comment, a module name or a parameter.

Only the first equals sign in a parameter is significant. Whitespace be-
fore 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.

LAUNCHING THE RSYNC DAEMON
The rsync daemon is launched by specifying the --daemon option to rsync.

The daemon must run with root privileges if you wish to use chroot, to
bind to a port numbered under 1024 (as is the default 873), or to set
file ownership. Otherwise, it must just have permission to read and
write the appropriate data, log, and lock files.

You can launch it either via inetd, as a stand-alone daemon, or from an
rsync client via a remote shell. If run as a stand-alone daemon then
just run the command "rsync --daemon" from a suitable startup script.

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 con-
nection.

GLOBAL PARAMETERS
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 con-
tains 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 com-
mand-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 op-
tion.

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 lis-
tens 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 parame-
ters. 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 ex-
ist 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 %%.

MODULE PARAMETERS
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 lead-
ing 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 val-
ues for multiple modules.

As with GLOBAL PARAMETERS, you may use references to environment vari-
ables 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 parame-
ter for each module in rsyncd.conf.

If the value contains a "/./" element then the path will be di-
vided 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 in-
side-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 implemen-
tation 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 ch-
root 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 "un-
set" 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. Ex-
plicitly 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 use-
ful 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 in-
terpret 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 en-
abled (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 nu-
meric 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 "ex-
clude" (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 ch-
root"), 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 in-
formation about the module and/or the copy request.

There is a sample python script in the support dir named "name-
convert" 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-ch-
root modules. Also keep in mind that uid/gid preservation re-
quires 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-per-
missions 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 set-
ting 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 sym-
links, 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 re-
move this prefix from your symlinks.

When this parameter is disabled on a writable module and "use ch-
root" 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 mod-
ule's filenames are stored. If the client uses an --iconv op-
tion, 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 mod-
ule 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 simul-
taneous 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 nega-
tive value disables the module. See also the "lock file" parame-
ter.

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 autho-
rization 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 fa-
tal 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 set-
tings. The latter sets the daemon's log file and the default for
all the modules, which still allows modules to override the de-
fault 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 dae-
mon. This setting has no effect if the "log file" setting is a
non-empty string (either set in the per-modules settings, or in-
herited 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 inher-
ited 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 ver-
bose 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 con-
nections" 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 down-
load 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 trans-
ferred. 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 ac-
cess 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 po-
tentially client-controlled DNS server may still reveal to the
client that it hit an existing module. The default is for mod-
ules 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 de-
fault 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 con-
tain a space. In either case any leading and/or trailing white-
space 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 un-
set, 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 speci-
fied. 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/in-
clude. 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" parame-
ter. 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 "ex-
clude 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 de-
scription 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 permis-
sions when the client does not specify --perms. See the descrip-
tion of the --chmod rsync option and the chmod(1) manpage for in-
formation 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 in-
stance, you could disable group write permissions on the server
while having it appear to be on to the clients. See the descrip-
tion of the --chmod rsync option and the chmod(1) manpage for in-
formation 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 user-
names that will be allowed to connect to this module. The user-
names 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 re-
sponse authentication protocol is used for this exchange. The
plain text usernames and passwords are stored in the file speci-
fied 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, speci-
fying "@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 ad-
min 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-match-
ing 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 au-
thenticated.

See also the section entitled "USING RSYNC-DAEMON FEATURES VIA A
REMOTE SHELL CONNECTION" in rsync(1) for information on how han-
dle 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 au-
thenticating 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 com-
ment 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 "user-
name: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 in-
clude, 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 nor-
mally 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 connect-
ing 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 re-
verse DNS of the connecting IP (if "reverse lookup" is en-
abled), 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 spec-
ified, 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 connect-
ing 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" in-
stead.

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 oc-
curred 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" pa-
rameter.

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 apos-
trophes 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 com-
mand-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" parame-
ter. (A perl script that will summarize this default log format
is included in the rsync source code distribution in the "sup-
port" 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 out-
put 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 speci-
fied in seconds. A value of zero means no timeout and is the de-
fault. A good choice for anonymous rsync daemons may be 600 (giv-
ing 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 ab-
breviation, 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 vari-
ous delete options:

refuse options = c delete

The reason the above refuses all delete options is that the op-
tions 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 "!refus-
ing") 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 re-
fuses 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_COM-
PRESS_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 op-
tion.

Note that the "copy-devices" & "write-devices" options are re-
fused 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 ac-
cepted.

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" parame-
ter.

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 in-
stance: if it is set to "*" then it minimizes or disables com-
pression 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 dur-
ing the transfer. If the compression algorithm has an "off"
level, then no compression occurs for those files. If an algo-
rithms 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 parame-
ter 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 re-
turns 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 dis-
carded. 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 oth-
erwise 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 com-
mand 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 speci-
fied 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 "." in-
dicating 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 mod-
ule, 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.

CONFIG DIRECTIVES
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 pars-
ing 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 de-
faults 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 in-
side 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 direc-
tory.

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 snip-
pets 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).

AUTHENTICATION STRENGTH
The authentication protocol used in rsync is a 128 bit MD4 based chal-
lenge 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 au-
thentication is provided. Use ssh as the transport if you want encryp-
tion.

You can also make use of SSL/TLS encryption if you put rsync behind an
SSL proxy.

SSL/TLS Daemon Setup
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.

DAEMON CONFIG EXAMPLES
A simple rsyncd.conf file that allow anonymous rsync to a ftp area at
/home/ftp would be:

[ftp]
path = /home/ftp
comment = ftp export area

A more sophisticated example would be:

uid = nobody
gid = nobody
use chroot = 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

FILES
/etc/rsyncd.conf or rsyncd.conf