vpnc Connects Linux and Cisco VPNs

The Cisco VPN client, vpnc, enables our Linux workstation to connect to a Cisco router VPN concentrator PIX firewall. Until vpnc existed, corporate employees were often relegated to connecting to their company's network via a Windows machine or with Cisco's problematic VPN client for Linux. but not without slight configuration effort. In this article we show you how to get it up and running.

Some important information we will need:

IPSEC gateway: the hostname or IP of the VPN server
IPSEC ID: the group name
IPSEC secret: the shared password for the group
your username
your password

The group name and shared password is the most important mostly use method for connecting to the Cisco IPSEC VPN. In lieu of certificates, this pre-shared key enables the forming of an IPSEC tunnel based on the shared secret.

Instalation option:
This is Depend upon our Linux distribution, we will need to install the vpnc program before we can begin. Fedora, by default, now installs vpnc, so Fedora users can skip to the next section. Ubuntu users can run apt-get install vpnc as root.
we will likely want to use Network Manager to enable quick VPN connections. Fedora's Network Manager is already installed, but in Ubuntu we will need to install the network-manager-vpnc package and configure it.



Configuring vpnc Manually:
This steps is optional depend upon we configer it or skip this option. NetworkManager section below.

Now that vpnc is installed, we will notice an /etc/vpnc/ directory. This is where we will be working for a bit. Creating a configuration file is optional, but without it, we will enter all the necessary information manually every time we connect to the VPN. If we wish to test our IP, group information, and user credentials. The configuration file for vpnc is quite simple. Create a file named after the network we wish to connect to, for example: /etc/vpnc/enp.conf


Connecting and Disconnecting:
Now that the configuration file exists, we can simply run sudo vpnc enp.conf . we will now be connected to the VPN. If everything working fine and then we will notice a new 'tun' interface in the 'ifconfig' output. now we disconnect the vpn.Do not that the default route gets replaced with the VPN router when we are connected. now we remember to disconnect from the VPN when we are done.

Source: http://www.enterprisenetworkingplanet.com/_featured/article.php/3823781/vpnc-Connects-Linux-and-Cisco-VPNs.htm