http://www.enterprisenetworkingplanet.com/_featured/article.php/3823781/
    *   IPSEC gateway: the hostname or IP of the VPN server 
    * IPSEC ID: the groupname 
    * IPSEC secret: the shared password for the group 
    * your username 
    * your password

The configuration file for vpnc is quite simple. Create a file named after the network you wish to connect to, for example: /etc/vpnc/enp.conf

sudo vpnc enp.conf
sudo vpnc-disconnect