Nmap Your Network

Port scanning offers security professionals and systems administrators a fast and effective way to identify which services or applications their servers have open to the Internet or another network. Complex OSs, such as Windows 2000, support applications that can use hundreds of ports to communicate with other clients or servers. Long gone are the days of classifying a Web server as simply port 80. In a standard installation, running Microsoft Internet Information Services (IIS) 5.0 on Win2K leaves many ports open.

You can find many port scanners for Win2K, and several scanners offer a GUI that makes conducting a rudimentary network scan easy. My favorite Win2K port scanner is Insecure .Org's Nmap (which Fyodor wrote and eEye Digital Security ported to Win32) —because of its flexible command-line-driven scanning options and robust output formats. Nmap's port-scanning and fingerprinting capabilities make it a favorite in many UNIX systems administrators' toolkits. The current version of Nmap for Windows, Nmap 2.54, is still in beta but available for use. (For a basic review of port scanning, see the sidebar "A Port-Scanning Primer," page 11.) . . .