x86-64 AVX2 assemby implemenation of get_checksum1() (#174)

[rsync.git] / rsyncd.conf.5.md

# NAME

rsyncd.conf - configuration file for rsync in daemon mode

# SYNOPSIS

rsyncd.conf

# 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 available
modules.

# FILE FORMAT

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

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

Only the first equals sign in a parameter is significant. Whitespace before or
after the first equals sign is discarded. Leading, trailing and internal
whitespace in module and parameter names is irrelevant. Leading and trailing
whitespace in a parameter value is discarded. Internal whitespace within a
parameter value is retained verbatim.

Any line **beginning** with a hash (`#`) is ignored, as are lines containing
only whitespace. (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 connection.

# GLOBAL PARAMETERS

The first parameters in the file (before a [module] header) are the global
parameters.  Rsync also allows for the use of a "[global]" module name to
indicate the start of one or more global-parameter sections (the name must be
lower case).

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 %%.

[comment]: # (An OL starting at 0 is converted into a DL by the parser.)

0.  `motd file`

    This parameter allows you to specify a "message of the day" to display to
    clients on each connect. This usually contains site information and any
    legal notices. The default is no motd file.  This can be overridden by the
    `--dparam=motdfile=FILE` command-line option when starting the daemon.

0.  `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.

0.  `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.

0.  `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.

0.  `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 man page for the
    **setsockopt()** system call for details on some of the options you may be
    able to set. By default no special socket options are set.  These settings
    can also be specified via the `--sockopts` command-line option.

0.  `listen backlog`

    You can override the default backlog value when the daemon listens for
    connections.  It defaults to 5.

# 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 leading or trailing whitespace will be
discarded.  Also, the name cannot be "global" as that exact name indicates that
global parameters follow (see above).

As with GLOBAL PARAMETERS, you may use references to environment variables in
the values of parameters.  See the GLOBAL PARAMETERS section for more details.

0.  `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.

0.  `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`.

    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.

0.  `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).

    As an additional safety feature, you can specify a dot-dir in the module's
    "path" to indicate the point where the chroot should occur.  This allows
    rsync to run in a chroot with a non-"/" path for the top of the transfer
    hierarchy.  Doing this guards against unintended library loading (since
    those absolute paths will not be inside the transfer hierarchy unless you
    have used an unwise pathname), and lets you setup libraries for the chroot
    that are outside of the transfer.  For example, specifying
    "/var/rsync/./module1" will chroot to the "/var/rsync" directory and set
    the inside-chroot path to "/module1".  If you had omitted the dot-dir, the
    chroot would have used the whole path, and the inside-chroot path would
    have been "/".

    When both "use chroot" and "daemon chroot" are false, OR the inside-chroot
    path of "use chroot" is not "/", rsync will: (1) munge symlinks by default
    for security reasons (see "munge symlinks" for a way to turn this off, but
    only if you trust your users), (2) substitute leading slashes in absolute
    paths with the module's path (so that options such as `--backup-dir`,
    `--compare-dest`, etc. interpret an absolute path as rooted in the module's
    "path" dir), and (3) trim ".." path elements from args if rsync believes
    they would escape the module hierarchy.  The default for "use chroot" is
    true, and is the safer choice (especially if the module is not read-only).

    When this parameter is enabled *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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `munge symlinks`

    This parameter tells rsync to modify all symlinks in the same way as the
    (non-daemon-affecting) `--munge-links` command-line option (using a method
    described below).  This should help protect your files from user trickery
    when your daemon module is writable.  The default is disabled when
    "use chroot" is on with an inside-chroot path of "/", OR if "daemon chroot"
    is on, otherwise it is enabled.

    If you disable this parameter on a daemon that is not read-only, there are
    tricks that a user can play with uploaded symlinks to access
    daemon-excluded items (if your module has any), and, if "use chroot" is
    off, rsync can even be tricked into showing or changing data that is
    outside the module's path (as access-permissions allow).

    The way rsync disables the use of symlinks is to prefix each one with the
    string "/rsyncd-munged/".  This prevents the links from being used as long
    as that directory does not exist.  When this parameter is enabled, rsync
    will refuse to run if that path is a directory or a symlink to a directory.
    When using the "munge symlinks" parameter in a chroot area that has an
    inside-chroot path of "/", you should add "/rsyncd-munged/" to the exclude
    setting for the module so that a user can't try to create it.

    Note:  rsync makes no attempt to verify that any pre-existing symlinks in
    the module's hierarchy are as safe as you want them to be (unless, of
    course, it just copied in the whole hierarchy).  If you setup an rsync
    daemon on a new area or locally add symlinks, you can manually protect your
    symlinks from being abused by prefixing "/rsyncd-munged/" to the start of
    every symlink's value.  There is a perl script in the support directory of
    the source code named "munge-symlinks" that can be used to add or remove
    this prefix from your symlinks.

    When this parameter is disabled on a writable module and "use chroot" is
    off (or the inside-chroot path is not "/"), incoming symlinks will be
    modified to drop a leading slash and to remove ".." path elements that
    rsync believes will allow a symlink to escape the module's hierarchy.
    There are tricky ways to work around this, though, so you had better trust
    your users if you choose this combination of parameters.

0.  `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.

0.  `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.

0.  `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.

0.  `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).

0.  `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%

0.  `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.

0.  `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`.

0.  `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.

0.  `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.

0.  `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`.

0.  `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.

0.  `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 = *

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `secrets file`

    This parameter specifies the name of a file that contains the
    username:password and/or @groupname:password pairs used for authenticating
    this module. This file is only consulted if the "auth users" parameter is
    specified.  The file is line-based and contains one name:password pair per
    line.  Any line has a hash (#) as the very first character on the line is
    considered a comment and is skipped.  The passwords can contain any
    characters but be warned that many operating systems limit the length of
    passwords that can be typed at the client end, so you may find that
    passwords longer than 8 characters don't work.

    The use of group-specific lines are only relevant when the module is being
    authorized using a matching "@groupname" rule.  When that happens, the user
    can be authorized via either their "username:password" line or the
    "@groupname:password" line for the group that triggered the authentication.

    It is up to you what kind of password entries you want to include, either
    users, groups, or both.  The use of group rules in "auth users" does not
    require that you specify a group password if you do not want to use shared
    passwords.

    There is no default for the "secrets file" parameter, you must choose a
    name (such as `/etc/rsyncd.secrets`).  The file must normally not be
    readable by "other"; see "strict modes".  If the file is not found or is
    rejected, no logins for a "user auth" module will be possible.

0.  `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.

0.  `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:

    - a dotted decimal IPv4 address of the form a.b.c.d, or an IPv6 address of
      the form a:b:c::d:e:f. In this case the incoming machine's IP address
      must match exactly.
    - an address/mask in the form ipaddr/n where ipaddr is the IP address and n
      is the number of one bits in the netmask.  All IP addresses which match
      the masked IP address will be allowed in.
    - an address/mask in the form ipaddr/maskaddr where ipaddr is the IP
      address and maskaddr is the netmask in dotted decimal notation for IPv4,
      or similar for IPv6, e.g. ffff:ffff:ffff:ffff:: instead of /64. All IP
      addresses which match the masked IP address will be allowed in.
    - a hostname 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).
    - 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.
    - 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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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.

0.  `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:

    - %a the remote IP address (only available for a daemon)
    - %b the number of bytes actually transferred
    - %B the permission bits of the file (e.g. rwxrwxrwt)
    - %c the total size of the block checksums received for the basis file
      (only when sending)
    - %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.
    - %f the filename (long form on sender; no trailing "/")
    - %G the gid of the file (decimal) or "DEFAULT"
    - %h the remote host name (only available for a daemon)
    - %i an itemized list of what is being updated
    - %l the length of the file in bytes
    - %L the string "` -> SYMLINK`", "` => HARDLINK`", or "" (where `SYMLINK`
      or `HARDLINK` is a filename)
    - %m the module name
    - %M the last-modified time of the file
    - %n the filename (short form; trailing "/" on dir)
    - %o the operation, which is "send", "recv", or "del." (the latter includes
      the trailing period)
    - %p the process ID of this rsync session
    - %P the module path
    - %t the current date time
    - %u the authenticated username or an empty string
    - %U the uid of the file (decimal)

    For a list of what the characters mean that are output by "%i", see the
    `--itemize-changes` option in the rsync manpage.

    Note that some of the logged output changes when talking with older rsync
    versions.  For instance, deleted files were only output as verbose messages
    prior to rsync 2.6.4.

0.  `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).

0.  `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`, `--protect-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 is better to set the "dont compress"
    daemon parameter to "`*`" because that disables 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 probably want to match
    "`!compress*`" so that you also accept the `--compress-level` option.

    Note that the "write-devices" option is refused by default, but can be
    explicitly accepted with "`!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:

    - `--server`: Required for rsync to even work.
    - `--rsh`, `-e`: Required to convey compatibility flags to the server.
    - `--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`.
    - `--sender`: Use "write only" parameter instead of refusing this.
    - `--dry-run`, `-n`: Who would want to disable this?
    - `--protect-args`, `-s`: This actually makes transfers safer.
    - `--from0`, `-0`: Makes it easier to accept/refuse `--files-from` without
      affecting this helpful modifier.
    - `--iconv`: This is auto-disabled based on "charset" parameter.
    - `--no-iconv`: Most transfers use this option.
    - `--checksum-seed`: Is a fairly rare, safe option.
    - `--write-devices`: Is non-wild but also auto-disabled.

0.  `dont compress`

    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 (such as zlib/zlibx) then no
    compression occurs for those files.  Other algorithms have the level
    minimized to reduces 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 not compressed by default.  Specifying a
    value for the "dont compress" parameter changes the default when the daemon
    is the sender.

0.  `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-detatch` 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:

    - `RSYNC_MODULE_NAME`: The name of the module being accessed.
    - `RSYNC_MODULE_PATH`: The path configured for the module.
    - `RSYNC_HOST_ADDR`: The accessing host's IP address.
    - `RSYNC_HOST_NAME`: The accessing host's name.
    - `RSYNC_USER_NAME`: The accessing user's name (empty if no user).
    - `RSYNC_PID`: A unique number for this transfer.
    - `RSYNC_REQUEST`: (pre-xfer only) The module/path info specified by the
      user.  Note that the user can specify multiple source files, so the
      request can be something like "mod/path1 mod/path2", etc.
    - `RSYNC_ARG#`: (pre-xfer only) The pre-request arguments are set in these
      numbered values. RSYNC_ARG0 is always "rsyncd", 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.
    - `RSYNC_EXIT_STATUS`: (post-xfer only) the server side's exit value.  This
      will be 0 for a successful run, a positive value for an error that the
      server generated, or a -1 if rsync failed to exit properly.  Note that an
      error that occurs on the client side does not currently get sent to the
      server side, so this is not the final exit status for the whole transfer.
    - `RSYNC_RAW_STATUS`: (post-xfer only) the raw exit value from
      **waitpid()**.

    Even though the commands can be associated with a particular module, they
    are run using the permissions of the user that started the daemon (not the
    module's uid/gid setting) without any chroot restrictions.

    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 parsing as
globals/defaults, and leaving the defaults unchanged for the parsing of the
rest of the parent file.

The `&merge` directive, on the other hand, treats the file's contents as if it
were simply inserted in place of the directive, and thus it can set parameters
in a module started in another file, can affect the defaults for other files,
etc.

When an `&include` or `&merge` directive refers to a directory, it will read in
all the `*.conf` or `*.inc` files (respectively) that are contained inside that
directory (without any recursive scanning), with the files sorted into alpha
order.  So, if you have a directory named "rsyncd.d" with the files "foo.conf",
"bar.conf", and "baz.conf" inside it, this directive:

>     &include /path/rsyncd.d

would be the same as this set of directives:

>     &include /path/rsyncd.d/bar.conf
>     &include /path/rsyncd.d/baz.conf
>     &include /path/rsyncd.d/foo.conf

except that it adjusts as files are added and removed from the directory.

The advantage of the `&include` directive is that you can define one or more
modules in a separate file without worrying about unintended side-effects
between the self-contained module files.

The advantage of the `&merge` directive is that you can load config snippets
that can be included into multiple module definitions, and you can also set
global values that will affect connections (such as `motd file`), or globals
that will affect other include files.

For example, this is a useful /etc/rsyncd.conf file:

>     port = 873
>     log file = /var/log/rsync.log
>     pid file = /var/lock/rsync.lock
>
>     &merge /etc/rsyncd.d
>     &include /etc/rsyncd.d

This would merge any `/etc/rsyncd.d/*.inc` files (for global values that should
stay in effect), and then include any `/etc/rsyncd.d/*.conf` files (defining
modules without any global-value cross-talk).

# AUTHENTICATION STRENGTH

The authentication protocol used in rsync is a 128 bit MD4 based challenge
response system. This is fairly weak protection, though (with at least one
brute-force hash-finding algorithm publicly available), so if you want really
top-quality security, then I recommend that you run rsync over ssh.  (Yes, a
future version of rsync will switch over to a stronger hashing method.)

Also note that the rsync daemon protocol does not currently provide any
encryption of the data that is transferred over the connection. Only
authentication is provided. Use ssh as the transport if you want encryption.

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

# SSL/TLS Daemon Setup

When setting up an rsync daemon for access via SSL/TLS, you will need to
configure a proxy (such as haproxy or nginx) as the front-end that handles the
encryption.

- 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.
- You should consider turning on the `proxy protocol` 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 "proxy protocol = true"
>        proxy_timeout 1m;
>        proxy_connect_timeout 5s;
>    }
> }
> ```

# 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

# SEE ALSO

**rsync**(1), **rsync-ssl**(1)

# BUGS

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

# VERSION

This man page is current for version @VERSION@ of rsync.

# CREDITS

rsync is distributed under the GNU General Public License.  See the file
COPYING for details.

The primary ftp site for rsync is <ftp://rsync.samba.org/pub/rsync>

A web site is available at <https://rsync.samba.org/>.

We would be delighted to hear from you if you like this program.

This program uses the zlib compression library written by Jean-loup Gailly and
Mark Adler.

# THANKS

Thanks to Warren Stanley for his original idea and patch for the rsync daemon.
Thanks to Karsten Thygesen for his many suggestions and documentation!

# AUTHOR

rsync was written by Andrew Tridgell and Paul Mackerras.  Many people have
later contributed to it.

Mailing lists for support and development are available at
<https://lists.samba.org/>.