how API features original (if any) lwip (2001) C src- embedded custom v4,v6,ipfwd,tcp scratch Seastar (2014) C++17 static lib custom v4,tcp,dpdk scratch OSv (2013) C++/C static lib POSIX v4,tcp (freebsd) gVisor (2018) golang go pkg custom v4,v6,tcp scratch (netstack mTCP (2014) C static lib custom v4,tcp,dpdk scratch rump (2007) C,asm static/sh lib POSIX v4,v6,ipfwd,tcp NetBSD Linux (1991) C,asm (kernel) POSIX v4,v6,ipfwd,tcp,xdp? Linux LKL (2007?) C,asm static/sh lib POSIX v4,v6,ipfwd,tcp,dpdk Linux 21