Simon works on the systems staff of the School of Informatics, University of Edinburgh. He has contributed to many free software packages, mainly concentrating on authentication and authorisation improvements. He wrote the Kerberos support in OpenSSH, and has contributed enterprise authentication support to Thunderbird, Pidgin, Adium, Psi and Jabberd2. His work with OpenAFS includes maintenance of their Linux packaging, as well as development of disconnected access technologies.