I am looking for a way to secure my servers with the following setup: I have a server where I can log in via SSH. The main account there (named "foo") is secured by a keybased login with password. I have another user account (named "bar") that I use to log in via cronjobs running on other servers - this one also has keybased login, but without password.
Now I want to limit access to this machine for the "bar" account. The account should only be accessible via known IPs. However, the "foo" account should not be affected by this, this one should basically be accessible from any IP.
How can I manage this? Or is there a simpler solution to everything?