cryptcat

Cryptcat is the standard netcat enhanced with twofish encryption.

Twofish is courtesy of counterpane, and cryptix. We started with the
Java version of twofish from cryptix, converted it to C++ (don't ask why),
and enhanced it by adding CBC mode and the ciphertext stealing technique
from Applied Cryptography (pg. 196)

How do you use it?

Machine A: cryptcat -l -p 1234 < testfile
Machine B: cryptcat <machine A IP> 1234

This is identical to the normal netcat options for doing exactly the
same thing. However, in this case the data transferred is encrypted.

For more information about netcat see net/netcat port.