OpenConnect is a client for Cisco's AnyConnect SSL VPN, which is supported by the ASA5500 Series, by IOS 12.4(9)T or later on Cisco SR500, 870, 880, 1800, 2800, 3800, 7200 Series and Cisco 7301 Routers, and probably others.

OpenConnect is released under the GNU Lesser Public License, version 2.1.

Like vpnc, OpenConnect is not officially supported by, or associated in any way with, Cisco Systems. It just happens to interoperate with their equipment.

Development of OpenConnect was started after a trial of their "official" client under Linux found it to have many deficiencies:

Naturally, OpenConnect addresses all of the above issues, and more.