Comment by alexflint

Yep. This is the first time I've mentioned this but there are actually two implementations of this in the codebase -- one uses gVisor and one is an incredibly bare-bones TCP implementation that I wrote myself in 550 lines of Go code (tcp.go). The home-grown one isn't used by default and it doesn't support much of TCP proper, but it actually works pretty well. You can use it with `--stack=homegrown`.