support VPN over tcp
Right now we hardcode the use of udp in the VPN. There is a protocols
section in the eip-services.json
that tells the client which protocols the provider supports.
Ideally we'll try first udp if the provider supports it, and falls back to tcp if udp didn't work or is not supported.
I'm noticing that some providers doesn't claim to support udp in their eip-services.json but bitmask works fine with them. Maybe we'll need to report a bug to platform.