Discard malformed fake TCP frames instead of panicking so OpenWrt
nodes can survive unexpected or truncated packets.
Also emit the correct IPv6 ethertype and cover the parser with
round-trip and truncation regression tests.
support faketcp to avoid tcp-over-tcp problem.
linux/macos/windows are supported.
better to be used in internet env, the maximum
performance is majorly limited by windivert/raw socket.
KKRainbow