RESTRICTED-SSH-COMMANDS

NAME

restricted−ssh−commands − Restrict SSH users to a predefined set of commands

SYNOPSIS

/usr/lib/restricted−ssh−commands [config]

DESCRIPTION

restricted-ssh-commands is intended to be called by SSH to restrict a user to only run specific commands. A list of allowed regular expressions can be configured in /etc/restricted−ssh−commands/. The requested command has to match at least one regular expression. Otherwise it will be rejected.

restricted-ssh-commands is useful to grant restricted access via SSH to do only certain task. For example, it could allow a user to upload a Debian packages via scp and run reprepro processincoming.

The optional config parameter is the name of the configuration inside /etc/restricted−ssh−commands/ that should be used. If config is omitted, the user name will be used.

USAGE

Create a configuration file in /etc/restricted−ssh−commands/$config and add following line to ~/.ssh/authorized_keys to use it

    command="/usr/lib/restricted−ssh−commands",no−port−forwarding,\
    no−X11−forwarding,no−agent−forwarding,no−pty ssh−rsa [...]

EXIT STATUS

restricted-ssh-commands will exit with the exit status from the called command if the command is allowed and therefore executed. If the command is rejected, restricted-ssh-commands will exit with one of the following exit codes.

EXAMPLES

Imagine you have a Debian package repository on a host using reprepro and you want to allow package upload to it. Assuming the user is reprepro and the package configuration is stored in /srv/reprepro, you would create the configuration file /etc/restricted−ssh−commands/reprepro containing these three regular expressions:

    ^scp −p( −d)? −t( −−)? /srv/reprepro/incoming(/[^ /]*)?$
    ^chmod 0644 /srv/reprepro/incoming/[^ /]*$
    ^reprepro ( −V)? −b /srv/reprepro processincoming foobar$

FILES

The configuration files are placed in /etc/restricted−ssh−commands/. Each line in the configuration file represents one POSIX extended regular expression ( ERE ). Lines starting with # are considered as comments and are ignored. Empty lines (containing only whitespaces) are ignored, too.

SEE ALSO

Regular expressions on http://tldp.org/LDP/Bash−Beginners−Guide/html/sect_04_01.html

Section 9.4 Extended Regular Expressions ( ERE ) on http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html

AUTHOR

restricted-ssh-commands and this manpage have been written by Benjamin Drung <benjamin DOT drung AT profitbricks DOT com>.