Harald Welte is communications security consultalt for more than a decade. He was co-author of tne netfilter/iptables packet filter in the Linux kernel and has since then been involved in a variety of Free Software based implementations of protocol stacks for RFID, GSM, GPRS, and TETRA. His main interest is to look at security of communication systems beyond the IP-centric mainstream. Besides his consulting work, he is the general manager of Sysmocom GmbH, providing custom tailored communications solutions to customers world-wide.