OpenConnect SSL VPN server compatible with Cisco's AnyConnect VPN protocolhttp://www.infradead.org/ocserv/
OpenConnect server (ocserv) is an SSL VPN server. Its purpose is to be a secure, small, fast and configurable VPN server. It implements the OpenConnect SSL VPN protocol, and has also (currently experimental) compatibility with clients using the AnyConnect SSL VPN protocol. The OpenConnect protocol provides a dual TCP/UDP VPN channel, and uses the standard IETF security protocols to secure it.
Ocserv's main features are security through privilege separation and sandboxing, accounting, and resilience due to a combined use of TCP and UDP. Authentication occurs in an isolated security module process, and each user is assigned an unprivileged worker process, and a networking (tun) device. That not only eases the control of the resources of each user or group of users, but also prevents data leak (e.g., heartbleed-style attacks), and privilege escalation due to any bug on the VPN handling (worker) process. A management interface allows for viewing and querying logged-in users.