Even after installing network-manager, network-manager-gnome, network-manager-vpnc, and adding a VPN, actually launching it failed -- no authentication dialog would show.
It was definitely a GUI issue as running vpnc from commandline succeeded.
As a test, run
sudo vpnc --gateway <gateway-IP> --id <cisco-group-id> --username <username>
To disconnect use:
If you can connect, you know your vpn subsystem is operational.
So first install the necessary components:
sudo aptitude install vpnc vpnc-scripts network-manager network-manager-gnome network-manager-vpnc network-manager-vpnc-gnome
To permanently add the nm-applet to your panel, in XFCE, go to Applications(Menu)>Settings>Session and Startup>Application Autostart tab and enable "Network". This will add the applet upon next session start. You MUST have the "Notification Area" applet added to the panel.
To temporarily show the applet without logout or restarting, run
nm-applet & ; exit
Now initially, Network-Manager will not be managing your connection, so edit the config to enable management of your existing wired connection. For me this was named "ifupdown (eth0)": (reference)
sudo nano /etc/NetworkManager/NetworkManager.confand set in the config file
Then restart the network-manager:
sudo /etc/init.d/network-manager restart
Now add your VPN settings and everything should work as expected.