Prevent Screen from creating sub shells

Question

I'm running a Linux system that starts a custom text mode application from the .bashrc. The users are getting disconnected due to network dropouts.

I had the idea that I'd use screen to allow them to get back to the prior session, but I like to make sure that they can't open a subshell that allows access to the UNIX command line (or for that matter, another login).

I've modified .screenrc with the following: bind c bind ^c

To prevent the Control-A Control-C command from working. Are are any other security issues that I need to be a where of here?

Answer 1

You'll have to prevent users from doing C-a : shell as well, and probably many other commands. Look into screen acl commands. Start with aclchg $USER -x ? and enable the commands you see fit.

Answer 2

I can't help with the screen part but wanted to ask if you have made sure users are not able to suspend your application (for example by pressing Control-Z) and getting shell access this way?

just my 2¢ Marcel