Add an access control mechanism.

[GrahamDumpleton]

Add some sort of password mechanism.

This will be tricky as in application part can't turn off echo of a password unless it talks telnet protocol if being communicated to via telnet over INET.

Instead the client side perhaps could have a command which can be run from shell to set the password to be used when connecting to a server and send it transparently as first command. The client can then perhaps turn off echo in raw input mode.

Another option for INET socket is to implement some sort of allowed client host access list.