In order to be interoperable with other data centers via IPsec, VNS3 supports a wide range of systems and standards.
Preferred: Most models from Cisco Systems*, Juniper, Watchguard, Dell SONICWALL, Netgear, Fortinet, Barracuda Networks, Check Point*, Zyxel USA, McAfee Retail, Citrix Systems, Hewlett Packard, D-Link, WatchGuard, Palo Alto Networks, OpenSwan, pfSense, MikroTik, and Vyatta.
Best Effort: Any IPsec device that supports: IKE1 or IKE2, AES256 or AES128 or 3DES, SHA1 or MD5, and most importantly NAT-Traversal standards.
Known Exclusions: Checkpoint R65-R80 require native IPSec connections as Checkpoint does not conform to NAT-Traversal Standards in these versions. In Checkpoint R80+, GuiDBedit must be used to force either native IPsec or NAT-T in order to maintain a reliable connection. (See https://support.cohesive.net/support/solutions/articles/31000156433-nat-t-compatibility-with-check-point-devices)
Cisco ASA 8.4(2)-8.4(any) bugs prevent a stable connection from being maintained.