A lightweight version netcat extended with twofish encryption
Cryptcat is a simple Unix utility which reads and writes data across
network connections, using TCP or UDP protocol while encrypting the
data being transmitted.
It is designed to be a reliable "back-end" tool that can be used directly
or easily driven by other programs and scripts. At the same time, it is a
feature-rich network debugging and exploration tool, since it can create
almost any kind of connection you would need and has several interesting
built-in capabilities.