In 1993, Assange gave technical advice to the Victoria Police Child Exploitation Unit and assisted with prosecutions.  In the same year, he was involved in starting one of the first public Internet service providers in Australia, Suburbia Public Access Network.  He began programming in 1994, authoring or co-authoring the TCP port scanner Strobe (1995), patches to the open-source database PostgreSQL (1996), the Usenet caching software NNTPCache (1996), the Rubberhose deniable encryption system (1997) (which reflected his growing interest in cryptography), and Surfraw, a command-line interface for web-based search engines (2000).  During this period, he also moderated the AUCRYPTO forum, ran Best of Security, a website "giving advice on computer security" that had 5,000 subscribers in 1996, and contributed research to Suelette Dreyfus's Underground (1997), a book about Australian hackers, including the International Subversives.  In 1998, he co-founded the company Earthmen Technology.