l0pht Heavy Industries
 - This page I have run into several times.  There security section is great! They posted the getopt() buffer overflow exploit for solaris originally 
Atlantic Systems Group
 - ASG specialises in UNIX system and network security.  We provide both our TurnStyle family of security products and security consulting services. 
DewPoint Distributed Solutions, Inc.
 - DewPoint is a world-wide distributor of WordPerfect for UNIX, InterScan VirusWall, and Other Internet security Products. 
Federated Software Group Inc.
Firewalls R Us Inc.
FSA Corporation, PowerBroker, and PowerLogin
 - FSA Corporation develops and sells UNIX system software, including two security products. 
Great Circle Associates
 - Specializes in Internet Firewall Security 
Haystack Labs' Inc.
 -  the preeminent supplier of tools for user accountability on Unix systems and networks. Active Security for Open Systems. 
Hervé Schauer Consultants
 - consulting company specialized in Internet, UNIX and TCP/IP security, and its firewall software: HSC-GK. 
Integrated Designs
 - Exclusive dealer for Digital Secured Networks, an intranet security device...The hackers worst nightmare!! 
Internet Security Systems
 - Internet Scanner lets you find your network security holes before the hackers do. 
Network-1 Software and Technology, Inc.
 - FireWall/Plus a complete DOS-based firewall that bucks the UNIX trend. 
PDC Services
 - Network Security Solutions for Inter/intranet firewall security.  Installation, integration, consulting and training. 
Raptor Systems
 - Designs, manufactures and markets the Eagle family of real-time network security products. Based on an application-level firewall architecture  
Secure Computing Corporation
 - Worry free information sharing in a changing world. 
Technologic, Inc.
 - the leader in Internet security and manufacturer of the Interceptor firewall. 
Trusted Information Systems, Inc.
 - Dedicated to accelerating the international availability of information systems security solutions through research, consulting, and product development.