First be sure to have the Network Manager plugin for Cisco VPN: network-manager-vpnc-gnome.
To do it, open Ubuntu Software Center and search network-manager.
So click on More info button.
In Add-on section be sure you have selected the network-manager-vpnc-gnome plugin. If not, select it and click on Apply Changes button.
click on Add button
select the type of connection: Cisco compatible VPN (vpnc)
give a name to your connection, then, in the VPN tab, input the credentials to connect to the VPN
and save all.
Now you can connect to VPN selecting it from Network Manager.
Usually, when you are connected to a VPN, all traffic goes through it and is possible that you are not able to browse internet, send or receive e-mails, use skype and other services due to the firewall of the network that blocking you.
To solve this problem, you have to specify to use the VPN tunnel only for the resources on its network.
To do it Edit your VPN configuration and click on Routes button in the IPv4 Setting Tab
Add the information about the network of the VPN and select Use this connection only for resources on its network.
Before to end this post I’d like to write about an interesting particular: when you install the network-manager plugin for Cisco VPN, the vpnc package is installed, too.
It provides some interesting commands including pcf2vpnc.
This command permit to decode the Group password (IPSec secret) from a PCF file usually used from Cisco VPN client for Windows.
## generated by pcf2vpnc IPSec ID (group-name) IPSec gateway (IP-Host) IPSec secret (password) Xauth username (user) IKE Authmode psk IPSec secret is the password coded in PCF file at the following parameter: enc_GroupPwd=5296B6F8C0B02555A3AFFD7F78524FA29...