Helpful Links
List Maintainer of Security Tools
Online Anti-Virus and Malware Scanners
ESET Online Scanner
Trend Micro's Housecall
Malware - Antispyware Scanners
Malware Bytes
AVG Anti-Virus Free Edition
Lavasoft's Ad-Aware Free Edition
Auditing and Scanning Tools
Backtrack is the most top rated linux live distribution focused on penetration testing. With no installation whatsoever, the analysis platform is started directly from the CD-Rom and is fully accessible within minutes.
Nmap "Network Mapper") is a popular, free and open source (license) utility for network exploration or security auditing.
Nessus is a proprietary comprehensive vulnerability scanning software. It is free of charge for personal use in a non-enterprise environment. Its goal is to detect potential vulnerabilities on the tested systems.
The Metasploit Project is a computer security project which provides information about security vulnerabilities and aids in penetration testing and IDS signature development. Its most well-known sub-project is the Metasploit Framework, a tool for developing and executing exploit code against a remote target machine.
Virtual Private Network
Adito is an open-source fork of the SSL Explorer project. The company that created and maintained the open source project, 3SP, was acquired by Barracuda Networks.
Misc Tools