google:
Install the command-line client.
sudo apt-get install vpnc
Convert the PCF file to a native configuration file.
pcf2vpnc NETWORK.pcf NETWORK.conf
Secure the credentials from prying eyes.
chmod 600 NETWORK_NAME.conf
Edit the NETWORK_NAME.conf file to add your username and password.
Start it with:
sudo vpnc /path/to/vpn/configs/NETWORK/NETWORK.conf
If it doesn't work, add the "--enable-1des" option, but make sure to tell the system administrator(s) that they need to upgrade their configuration as it's not as secure as it could be.
sudo vpnc --enable-1des /path/to/vpn/configs/NETWORK/NETWORK.conf
Terminate your connection as needed.
sudo vpnc-disconnect
source:
http://colans.net/blog/installing-vpn-pcf-files-ubuntu-1304