Harald Welte is a data communications freelancer, enthusiast and hacker
who is working with Free Software (and particularly GNU/Linux)
since 1995  His major code contribution to the Linux kernel was as a
core developer of the netfilter/iptables packet filter.

He has co-started a number of other Free Software and Open Hardware
projects, from RFID to telephony - including the worlds first 100% Open
Free Software based mobile phone OpenMoko.

Aside from his technical contributions, Harald has been pioneering the legal
enforcement of the GNU GPL license as part of his gpl-violations.org project.
More than 150 inappropriate use of GPL licensed code by commercial companies
have been resolved as part of this effort, both in court and out of court. He
has received the 2007 "FSF Award for the Advancement of Free Software" and the
"2008 Google/O'Reilly Open Source award: Defender of Rights".

In 2008, Harald started to work on Free Software on the GSM protocol side, both
for passive sniffing and protocol analysis, as well as an actual network-side
GSM stack implementation called OpenBSC, which later developed towards
GPRS, EDGE and UMTS.  In 2010, he expanded those efforts by creating
OsmocomBB, a GSM telephony-side baseband processor firmware and
protocol stack.  Other projects include OsmocomTETRA, a receive-only
implementation of the ETSI TETRA radio interface.