For a mind boggling good time (If you can have that in C) take a look aftr.c. This is Comcast's open source ipv4 -> ipv6 routing code. I'm not saying it's prett

For a mind boggling good time (If you can have that in C) take a look aftr.c. This is Comcast's open source ipv4 -> ipv6 routing code. I'm not saying it's pretty... but if your interest lay in C and systems level bit twiddling it's 13000 lines of good times.