Harald Welte
Board Member at hmw-consulting.de
Berlin, Germany
Summary
👤
Senior🎓
Top SchoolHarald Welte is a seasoned telecommunications and Linux networking expert with 26 years of hands-on experience building and securing protocol stacks from 2G to 5G. As co-founder and managing director of sysmocom and founder of the Osmocom project, he has driven open-source cellular implementations (OpenBSC, OsmocomBB) and commercial small-form-factor BTS products while consulting globally on FOSS licensing and cellular security. His deep kernel and protocol work — including netfilter/iptables leadership and contributions to projects like srsRAN, Open5GS and Wireshark dissectors — combines low-level systems craftsmanship with practical interoperability fixes against 3GPP standards. He also founded gpl-violations.org, enforcing GPL compliance in industry, reflecting a rare mix of technical authority and legal/ethical stewardship. Based in Berlin, Harald is an autodidact whose career blends embedded Linux, SDR, and telecom core network development with long-term community building.
26 years of coding experience
3 years of employment as a software developer
computer science, electrical engineering, communications, computer science, electrical engineering, communications at Autodidact.
English, German, Portuguese
Github Skills (22)
c-language10
5g10
sdl10
lte10
gps10
4g10
l2tp10
c1110
networking10
c1710
network-protocol10
epc10
network10
3g10
protocols10
Programming languages (29)
Github contributions (5)
wireshark/wireshark
Jul 2016 - Dec 2022
Read-only mirror of Wireshark's Git repository at https://gitlab.com/wireshark/wireshark. ⚠️ GitHub won't let us disable pull requests. ⚠️ THEY WILL BE IGNORED HERE ⚠️ Upload them at GitLab instead.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:98 commits in 6 years 5 months
Contributions summary:Harald's contributions focused on enhancing the Wireshark network traffic analyzer's dissectors, specifically for the Ericsson-specific extensions in L2TP, various A-bis protocols like P-GSL and TFP, and the OsmoTRX protocol. The user added support for new information elements, message types, and protocols, improving the tool's ability to decode and display data from these GSM network components. They also improved existing dissectors such as BSSMAP and gsm_abis_om2000 to include better decoding.
tsharkgit-repositorywiresharkpacket-capturegitlab
open5gs/open5gs
Oct 2017 - Jul 2020
Open5GS is a C-language Open Source implementation for 5G Core and EPC, i.e. the core network of LTE/NR network (Release-17)
Role in this project:Backend Developer
Backend DeveloperContributions:1 review, 21 commits, 16 PRs in 2 years 9 months
Contributions summary:Harald primarily contributed to the backend functionality of the Open5GS project, focusing on core network (5G Core and EPC) implementation. Their contributions included fixing compilation issues related to SCTP and freeDiameter, improving code maintainability through argument type refinements, and addressing functional correctness by applying default values and correcting AVP handling in DIAMETER messages. The user also made improvements in the MME and HSS components, addressing RAU/TAU timer configurations and ensuring proper behavior.
open5gslteepccpp5g-core
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