VPNC - Client for Cisco 3000 VPN Concentrator

A VPN client compatible with Cisco's EasyVPN equipment.
Supports IPSec (ESP) with Mode Configuration and Xauth. Supports only
shared-secret IPSec authentication, 3DES, MD5, and IP tunneling.
It runs entirely in userspace.

WWW: http://www.unix-ag.uni-kl.de/~massar/vpnc/