last update:
If you need to install support for this VPN, do this:
root@nargothrond:~# apt-get install network-manager-vpnc-gnome
Find your Network Settings/Network Connections dashboard; it's usually accessible via an icon in your (Gnome) panel at top right. Choose Network Connections.
We're going in essence to add a new connection, so click the + sign.
Scroll down to the list of available VPN connections and choose the Cisco-compatible connection.
Next, click Create.
Now fill in the configuration.
If you need advanced configuration...
The result is...
I kept losing settings (entries) I'd made to /etc/hosts overnight or after reboot. It was mysterious because I thought I owned this file. Not so. And it's not really after reboot. It's because VPNC makes a copy of this file, in case it decides to change it (I guess, though I've never seen it add anything).
The solution is simple. If you add something to /etc/hosts, do it when VPNC is not running. Superstitiously, I don't add anything no matter what VPN is running—I have to run up to two of them in my work.