# rrsync

## NAME



           rrsync - a script to setup restricted rsync users via ssh logins
    


## SYNOPSIS



           rrsync [-ro|-wo] [-munge] [-no-del] [-no-lock] [-no-overwrite]  DIR
    
           The single non-option argument specifies the restricted _DIR_ to
           use. It can be relative to the user's home directory or an
           absolute path.
    
           The online version of this manpage (that includes cross-linking of
           topics) is available at 
           ⟨https://download.samba.org/pub/rsync/rrsync.1⟩.
    


## DESCRIPTION



           A user's ssh login can be restricted to only allow the running of
           an rsync transfer in one of two easy ways:
    
           o      forcing the running of the rrsync script
    
           o      forcing the running of an rsync daemon-over-ssh command.
    
           Both of these setups use a feature of ssh that allows a command to
           be forced to run instead of an interactive shell.  However, if the
           user's home shell is bash, please see BASH SECURITY ISSUE for a
           potential issue.
    
           To use the rrsync script, edit the user's **~/.ssh/authorized_keys**
           file and add a prefix like one of the following (followed by a
           space) in front of each ssh-key line that should be restricted:
    
               command="rrsync DIR"
               command="rrsync -ro DIR"
               command="rrsync -munge -no-del DIR"
    
           Then, ensure that the rrsync script has your desired option
           restrictions. You may want to copy the script to a local bin dir
           with a unique name if you want to have multiple configurations.
           One or more rrsync options can be specified prior to the _DIR_ if
           you want to further restrict the transfer.
    
           To use an rsync daemon setup, edit the user's
           **~/.ssh/authorized_keys** file and add a prefix like one of the
           following (followed by a space) in front of each ssh-key line that
           should be restricted:
    
               command="rsync --server --daemon ."
               command="rsync --server --daemon --config=/PATH/TO/rsyncd.conf ."
    
           Then, ensure that the rsyncd.conf file is created with one or more
           module names with the appropriate path and option restrictions.
           If rsync's **--config** option is omitted, it defaults to
           **~/rsyncd.conf**.  See the rsyncd.conf(5) manpage for details of how
           to configure an rsync daemon.
    
           When using rrsync, there can be just one restricted dir per
           authorized key.  A daemon setup, on the other hand, allows
           multiple module names inside the config file, each one with its
           own path setting.
    
           The remainder of this manpage is dedicated to using the rrsync
           script.
    


## OPTIONS



           **-ro** Allow only reading from the DIR. Implies **-no-del** and **-no-**
                  **lock**.
    
           **-wo** Allow only writing to the DIR.
    
           **-munge** Enable rsync's **--munge-links** on the server side.
    
           **-no-del**
                  Disable rsync's **--delete*** and **--remove*** options.
    
           **-no-lock**
                  Avoid the single-run (per-user) lock check.  Useful with
                  **-munge**.
    
           **-no-overwrite**
                  Enforce **--ignore-existing** on the server. Prevents
                  overwriting existing files when the server is the receiver.
    
           **-help** , **-h**
                  Output this help message and exit.
    


## SECURITY RESTRICTIONS



           The rrsync script validates the path arguments it is sent to try
           to restrict them to staying within the specified DIR.
    
           The rrsync script rejects rsync's **--copy-links** option (by default)
           so that a copy cannot dereference a symlink within the DIR to get
           to a file outside the DIR.
    
           The rrsync script rejects rsync's **--protect-args**(**-s**) option
           because it would allow options to be sent to the server-side that
           the script cannot check.  If you want to support **--protect-args** ,
           use a daemon-over-ssh setup.
    
           The rrsync script accepts just a subset of rsync's options that
           the real rsync uses when running the server command.  A few extra
           convenience options are also included to help it to interact with
           BackupPC and accept some convenient user overrides.
    
           The script (or a copy of it) can be manually edited if you want it
           to customize the option handling.
    


## BASH SECURITY ISSUE



           If your users have bash set as their home shell, bash may try to
           be overly helpful and ensure that the user's login bashrc files
           are run prior to executing the forced command.  This can be a
           problem if the user can somehow update their home bashrc files,
           perhaps via the restricted copy, a shared home directory, or
           something similar.
    
           One simple way to avoid the issue is to switch the user to a
           simpler shell, such as dash.  When choosing the new home shell,
           make sure that you're not choosing bash in disguise, as it is
           unclear if it avoids the security issue.
    
           Another potential fix is to ensure that the user's home directory
           is not a shared mount and that they have no means of copying files
           outside of their restricted directories.  This may require you to
           force the enabling of symlink munging on the server side.
    
           A future version of openssh may have a change to the handling of
           forced commands that allows it to avoid using the user's home
           shell.
    


## EXAMPLES



           The **~/.ssh/authorized_keys** file might have lines in it like this:
    
               command="rrsync client/logs" ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAzG...
               command="rrsync -ro results" ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAmk...
    


## FILES



           ~/.ssh/authorized_keys
    


## VERSION



           This manpage is current for version 3.4.1 of rsync.
    


## CREDITS



           rsync is distributed under the GNU General Public License.  See
           the file COPYING for details.
    
           An rsync web site is available at ⟨https://rsync.samba.org/⟩ and
           its github project is ⟨https://github.com/RsyncProject/rsync⟩.
    


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