TUND allows to organize IP over IP tunnel (IP packets are incapsulated
into UDP one). It works together with FreeBSD ipfw(8). Can be used
for tunneling private networks behinf NATD. Supports encryption with various
ciphers, RSA authentication, multiple and parallel tunnels (up to 65534
tunnels) with single UDP port.

Sergey Kosyakov
ks@itp.ac.ru