Linvpn is a secure socket layer for pppd. It
allows creation of virtual private networks by
using an IP routing system between PPP network
interfaces. Cryptography is done by libgcrypt's
3DES or blowfish, and Initialization Vector (IV)
is changed in each packet transmission. As linvpn
works as client and server, and communication is a
single TCP connection, it allows creation of
secure tunnels even in complex network layouts,
when one or both endpoints are behind a firewall
or NAT, with or without dynamic IP addresses.