using root with ssh 'command=' and authorized_keys

hank43 · 09-09-2006, 03:05 AM

i am trying to come up with a backup/restore plan. backupmachine will pull data from workmachine. thinking of using rsnapshot to do it.

what's the danger of configuring ssh on workmachine to allow root access without a passphrase and limiting the command using 'command=' in authorized_keys? if someone roots backupmachine, they are limited to workmachine by what i specified in 'command='

this is similar to what i am planning, but he prefers a backupuser on workmachine.
http://troy.jdmz.net/rsnapshot/

for my command in 'command=', i was going to use a script like the one below and list the commands i want allowed.

Code:

#!/bin/sh
  case "$SSH_ORIGINAL_COMMAND" in

    1)
        /bin/date
        ;;
    2)
       /usr/bin/who
        ;;
    3)
        /usr/bin/w
        ;;
  esac
exit 0

file permissions would be set to only allow root access to the script.

Lotharster · 09-11-2006, 06:51 AM

Yous hould be very careful which commands you allow in your script. If any of them can be subverted to get a shell (e. g. in vi, the :! command gives the user access to a shell), your attacker has unlimited root access to your machine. You should also very carefully analyse your script. Any bugs could be used to gain root access.

Therefore I'd rather set up a backup user.