Poul-Henning Kamp

Poul-Henning Kamp (born 1966) is a Danish computer software developer known for work on various projects. He currently resides in Slagelse, Denmark.

Poul-Henning Kamp
Poul-Henning Kamp with Tux
Born (1966-01-20) 20 January 1966
ResidenceSlagelse, Denmark
Other namesphk

Involvement in the FreeBSD project

Poul-Henning Kamp has been committing[1] to the FreeBSD project for most of its duration. He is responsible for the widely used MD5crypt implementation of the MD5 password hash algorithm,[2][3] a vast quantity of systems code including the FreeBSD GEOM storage layer, GBDE cryptographic storage transform, part of the UFS2 file system implementation, FreeBSD Jails, malloc library, and the NTP timecounters code.

Most notable projects

He is the lead architect and developer for the open source Varnish cache project, an HTTP accelerator.

In 2006, Kamp had a dispute with electronics manufacturer D-Link in which he claimed they were committing NTP vandalism by embedding the IP address of his NTP servers in their routers.[4][5] The dispute was resolved on 27 April 2006.[6]

Anti-Semitism Allegations

Poul-Henning Kamp has made various anti-semitic comments, blaming the world's Jews as collectively responsible for the actions of Israel. On May 8, 2019, he tweeted "I thought anti-semitism was *unfounded* hatred of Jews ? If you hate them because they did something awful, like implement apartheid, it is not anti-semitism, but perfectly justified critique of people who in particular should know better than that."[7] Clarifying on a blog post later, he wrote that "I will readily admit that it was probably not my most skilled use of Twitter, but I stand by my point." Kamp went on to say that he "detests their cowardice" for not being "appaled [sic] and up in arms over the atrocities against UNs Human Rights being done in the name of their religion."[8]


A post by Poul-Henning on the FreeBSD mailing lists[9] is responsible for the popularization of the term bike shed discussion, and the derived term bikeshedding, to describe Parkinson's law of triviality in open source projects - when the amount of discussion that a subject receives is inversely proportional to its importance.

Poul-Henning Kamp is known for his preference of a Beerware license to the GNU General Public License (GPL).[10]


Poul-Henning Kamp has published a substantial number of articles over the years in publications like Communications of the ACM and ACM Queue mostly on the topics of computing and time keeping. A selection of publications:


  1. "List of FreeBSD committers on Freebsd.org".
  2. "PHKs Bikeshed, MD5crypt Is No longer safe". Retrieved 13 March 2013.
  3. Norris, Jeff (2004). "Mission-Critical Development with Open Source Software: Lessons Learned". IEEE Software. IEEE Computer Society. 21 (1): 42–49. doi:10.1109/MS.2004.1259211.
  4. "D-Link Firmware Abuses Open NTP Servers".
  5. Kamp, Poul-Henning. "Open Letter to D-Link about their NTP vandalism". Archived from the original on 2006-04-08.CS1 maint: BOT: original-url status unknown (link)
  6. Kamp, Poul-Henning (2006-04-27). "2006-04-27 Update – Open Letter to D-Link about their NTP vandalism". people.freebsd.org. Retrieved 2017-03-01.
  7. https://twitter.com/bsdphk/status/1126199508449341440
  8. http://phk.freebsd.dk/sagas/israel/
  9. "A bike shed (any colour will do) on greener grass...", freebsd-hackers mailing list, 1999
  10. "Poul-Henning Kamp". Retrieved 10 January 2013.
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