Among other companies bought and sold by McAfee (formerly known as Network Associates) is Trusted Information Systems, which developed the Firewall Toolkit, which was the free software foundation for the commercial Gauntlet Firewall, which was later sold by McAfee to Secure Computing Corporation. Network Associates, as a result of brief ownership of TIS Labs/NAI Labs/Network Associates Laboratories/McAfee Research, was highly influential in the world of Open Source software, as that organization produced portions of the Linux, FreeBSD, and Darwin operating systems, and developed portions of the BIND name server software and SNMP version 3.

Leading up to the TIS Labs acquisition, McAfee had acquired Calgary, Alberta Canada-based FSA Corporation, which helped the company diversify its security offerings away from just client-based antivirus software by bringing on board its own network and desktop encryption technologies. The FSA team also oversaw the creation of a number of other technologies that were leading edge at the time, including firewall, file encryption, and public key infrastructure product lines. While those product lines had their own individual successes including PowerBroker (written by Dean Huxley and Dan Freedman and now sold by BeyondTrust), the growth of antivirus ware always outpaced the growth of the other security product lines. It is fair to say that the company remains best known for its antivirus and antispam product lines.

On June 9, 1998 Network Associates agreed to acquire Dr Solomon's Group P.L.C, the leading European manufacturer of antivirus software, for $642 million in stock.