Allow guest SSH login and redirect to a program

Question

Sometimes I get really silly ideas.

This time, the idea is to deliver an easter egg for anyone who decides to try and connect to my server via SSH. Doing so will run a program, such as easteregg.sh, which can provide something like a "hacking" minigame.

However, I have absolutely no idea how to do this! Obviously, such a thing would need to be unobtrusive to actual server admins trying to log in, so there'd need to be some way to distinguish that. Then there's the matter of actually triggering a program to run. Not to mention security: certainly don't want guest users to potentially access server files!

With all that in mind, is such a thing even remotely possible, or is it really just a stupid idea?

Answer 1

Have you tried changing the user's default shell to the program you're wanting to run upon login? Ultimately, that's all a default shell is: The thing that gets ran after the user successfully authenticates.

Answer 2

Have a look at /etc/passwd
The last column specifies to which shell the connection will be pointed. This does not have to be bash, but instead could be your customized shell.

Answer 3

Kippo is a SSH honeypot which provides an interactive fake shell, which logs all activity user has on the server.

However, it might not be completely suited for your use, since Kippo is an actual daemon that needs to bind to a port. So, if you have SSH installed in the standard port, you need to install Kippo on some other port, and it might not be that useful.