How to create a user that can login via SSH, but can't use shell commands?

Question

How to create a new user that can login via SSH, but can't use shell commands? I've tried to set /bin/false as the default shell to the user, but then I no longer can login via SSH.

Answer 1

You can create a new, small, "shell" (I used quotes because is not a real shell) as follow:

1. As root, create a new file in /bin directory, let say fakesh.

2. Add the following code inside /bin/fakesh file:

   #!/bin/bash
   echo -n "$ "
   while read cmd ; do 
       if [ "$cmd" = "exit" ]; then break; fi
       if [ "$cmd" != "" ]; then echo "The only one available command is: exit"; fi
       echo -n "$ "
   done
   

3. Save the file and make it executable for everyone:

   chmod +x /bin/fakesh
   

After these, just set /bin/fakesh as the default shell for your user. The user will be available to login his account via ssh, but he will not be able to execute any command except for exit.