Restricted Shell for SSH Server

If you use SSH Logins you can lock down the Console to a restriced shell with less enabled commands!

Remark: rbash is not 100% secure, Server should be never reachable to Consoles from Internet!!

This does not work with installed tmux or screen, cause Users can break out of rbash!

• Login as root User on the Server
• install rbash with:

apt-get install rbash

• rename bash by:

mv /bin/bash /bin/oldbash

• Disable other Shells for User

chmod o= /bin/oldbash
chmod 700 /bin/sh
chmod 700 /bin/dash

• create a symlink for rbash to bash

$ln -s /bin/bash /bin/rbash

• enable rbash by system setting /etc/shells

$echo '/bin/rbash' >> /etc/shells

• set user shell to /bin/rbash

$chsh   #set user shell to /bin/rbash

• Disable "chsh" Change Shell Command for Users

$chmod o= /bin/chsh

• Login as user and test linux commands..

• Purge tmux and screen Multiplexer if installed!