This sounds very similar to my slirpnetstack, which is using gvisor netstack to do, which I call translating L3 (packets) into L7 (userspace syscalls like conne

This sounds very similar to my slirpnetstack, which is using gvisor netstack to do, which I call translating L3 (packets) into L7 (userspace syscalls like connect()): https://github.com/majek/slirpnetstack/ https://github.com/majek/slirpnetstack/ (btw, gvisor netstack, while not without problems, is likely to be faster than libslirp, see benchmarks https://github.com/rootless-containers/rootlesskit/pull/101#issuecomment-577453708 https://github.com/rootless-containers/rootlesskit/pull/101#... )