Marcus J. Ranum is a computer and network security researcher and industry leader. He is credited with a number of innovations in firewalls, including building the first Internet email server for the whitehouse.gov domain, and intrusion detection systems. He has held leadership positions with a number of computer security companies, and is a Faculty member of the Institute for Applied Network Security. Ranum designed and implemented Digital Equipment Corporation’s Secure External Access Link (SEAL) (later AltaVista firewall), regarded as the first commercial bastion host firewall, in 1990. He left DEC to work for Trusted Information Systems (TIS) as chief scientist and development manager for Internet security products. It was at TIS that Ranum became responsible for the whitehouse.gov Internet email site. Once charged with that responsibility, Ranum advocated that the whitehouse.com domain be registered as well. Despite his advice, it was not registered by the government, but was later registered for an adult entertainment provider. At TIS, he developed the TIS Internet Firewall Toolkit (fwtk) under a grant from DARPA. After TIS, he worked for V-One as chief scientist, and was extensively involved in that company’s IPO. Three months after that IPO, Ranum formed his own company, Network Flight Recorder (NFR), and served as CEO for three years before stepping into a CTO role. Ranum later left NFR to consult for TruSecure, before joining Tenable Network Security as CSO.