Are root logins only allowed from that particular LAN? Because ssh localhost is a thing. I would say that the inability to obtain a session with elevated privi

Are root logins only allowed from that particular LAN? Because ssh localhost is a thing. I would say that the inability to obtain a session with elevated privileges from a normal session is key. The problem with sudo is that it gives the same shell some superpowers, so it's exploitable. Even ssh might be impenetrable, if not for the /dev/<pid>/fd of the ssh invocation, and even that can only read.