"Arguing for an increase in your IT security budget is often an arduous task, so many administrators turn to free open source tools to help get the job done. But how can they rely on tools with no commercial support and that never get past the beta version? Well, if you think like that, you need to think again. Many open source tools now compare favorably with commercial alternatives in terms of features, reliability and help forums. One in particular, Nmap, has become the tool of choice for many network and security administrators who want to map their networks and test them for vulnerabilities.
"Nmap (Network Mapper) Security Scanner, written by Fyodor and now up to version 4, provides a wide range of port-scanning techniques designed to rapidly scan networks, large and small, for network exploration and security auditing..."
