An implementation of auth is identd. https://en.wikipedia.org/wiki/Ident_protocol https://en.wikipedia.org/wiki/Ident_protocol It is a way for the server to v

An implementation of auth is identd. https://en.wikipedia.org/wiki/Ident_protocol https://en.wikipedia.org/wiki/Ident_protocol It is a way for the server to verify which username initiated a connection from the client by connecting back to the client on a privileged port and ask, referencing the local and remote port of the target connection.