trixd00r is an advanced and invisible userland backdoor based on TCP/IP for UNIX systems. It consists of a server and a client. The server sits and waits for magic packets using a sniffer. If a magic packet arrives, it will bind a shell over TCP or UDP on the given port or connecting back to the client again over TCP or UDP. The client is used to send magic packets to trigger the server and get a shell.
http://www.nullsecurity.net
