VPN connections are commonly used to connect to university or enterprise networks. This is often done with the help of the CISCO client, which is available for many operating systems, but which is not free software, of course.
In case you are using a GNU/Linux operating system (hopefully one of the free ones, like gNewSense), you might want to use the free VPNC instead of the ugly CISCO client.
The network administrator of the network you want to connect to will provide you with a configuration file filename.pcf. This file seems to be incompatible with the configuration files VPNC can read.
The Debian package (also gNewSense, Ubuntu, ...) comes with a translator called pcf2vpnc for configuration files. Unfortunately the program will be put in /usr/share/vpnc/, so you will have to give the full path probably.
$ /usr/share/vpnc/pcf2vpnc file.pcf file.conf
Put file.conf in /etc/vpnc/.
# vpnc file
(with or without the ".conf") and start your ssh session.