Poul-Henning Kamp

In 1994 he wrote md5crypt, the password hash with the $1$ prefix, because FreeBSD couldn't legally export the DES-based crypt from the US. It spread to Linux and Cisco gear and was the default for a decade. In 2012 Kamp publicly declared it unsafe himself — too fast for modern GPUs. Few authors write the obituary for their own code.

Jails, which shipped in FreeBSD 4.0 in 2000, confined processes to their own root filesystem and network address long before "container" was a buzzword. A 1999 post to freebsd-hackers, about how everyone has an opinion on the colour of the bike shed and nobody on the nuclear plant, gave us bikeshedding. He also wrote Varnish in 2006 and authored the Beerware licence.