Synaptic Package Manager –> search “vpn”

Using kvpnc.

kvpnc 0.9.6-1

Dependents:
vpnc 0.5.3r449-2
network-manager-vpnc 0.8-0ubuntu3
network-manager-vpnc-kde 0.9~svc1112085-0ubuntu4
network-manager-pptp 0.8-0ubuntu3
network-manager-pptp-gnome 0.8-0ubuntu3
pptp-linux 1.7.2-4

Looks like the 3 pptp-related packages are version-sensitive for kvpnc to launch.

C======

Update #1 Aug. 15, 2011

The method below is also worth trying since it has been more and more difficult to download old version of components mentioned above. The idea is also to use Ubuntu’s native VPN connection kit but add a Cisco IPsec plugin.

Note: One needs the authentication details at hand. All the information is stored in the *.pcf profile by the institute/company. The IP address, user ID, group ID are not encoded. However, the group password is. One should be able to convert that 40-letter password into a much shorter plain-text password composed of, for example, 7 letters, through a web-based program.

http://www.unfoldingcode.com/2011/08/how-to-install-cisco-vpn-client-on.html

Update #2 Aug. 16,2011

It indeed works in Ubuntu 11.04. But there seems to be a bug.

If you are quite confident about the accuracy of the VPN profile that is setup, you can try it.

Messages like “The VPN Connection *** failed” or “The VPN connections failed to start. Connection was not provided by any settings service” may pop up even if all the settings are correct.

Through trial and error, it is recommended to uncheck the “Connect automatically” in the settings.
If one unfortunately select the option, and later uncheck it, it is found that this does *NOT* take effect, regardless how much times one may try. The workaround is to create another VPN(does not have to be valid or to work), and toggle it. Then go back to try the first VPN. And voila! it just works….

The Settings under “Optional” can mostly be kept default except the User name:

“Domain” — blank;
“Encryption Method” — Secure;
“NAT traversal”— NAT-T when available;
“IKE DH Group” — DH Group 2.

It at least works with Rice VPN (Cisco).