strongSwan is an open source IPsec-based VPN solution.
Main features:
- Implements both the IKEv1 and IKEv2 (RFC 5996) key exchange protocols.
- Fully tested support of IPv6 IPsec tunnel and transport connections.
- Dynamical IP address and interface update with IKEv2 MOBIKE.
- Automatic insertion and deletion of IPsec-policy-based firewall rules.