UUCP remote.unknown File

The other file that affects the use of communication facilities is the remote.unknown file. This file is a binary program that executes when a machine not found in any of the Systems files starts a conversation. It logs the conversation attempt and drops the connection.

If you change the permissions of the remote.unknown file so it cannot execute, your system accepts connections from any system.

This program executes when a machine that is not in any of the Systems starts a conversation. It logs the conversation attempt but fails to make a connection. If you change the permissions of this file so it cannot execute (chmod 000 remote.unknown), your system accepts any conversation requests. This is not a trivial change, and you should have good reasons for doing it.