I am faced with two different user groups that need to offer VPN access to remote facilities' internal networks. In both cases, the remote networks contain devices (think lab equipment with network ports, but not "proper" servers) with rather non-standard access methods, requiring Layer 2 traffic to be routed through the VPN without interfering with it.
We have VPN solutions in place, but they require very specialized client setups. I am now looking for a recommendation for a VPN system that
- is available without license costs and ideally open source
- can handle Layer 2 traffic
- offers robust but not necessarily Snowden-grade security
- is (ideally) handled by default VPN clients in Windows, MacOS and Android and has good client support for Linux
We can handle the creation and management of X.509 certificates for users. Also, the work involved in setting up servers and clients is not a limiting factor (although we'd prefer not to have to dive into too obscure build routines).