SARA, spawn of SATAN
If you are an old school Linux or Unix user, you probably remember the System Administrator's Tool for Scanning Networks (SATAN). In 1995, SATAN brought browser-based network auditing to the world. Despite its initial splash, SATAN fell to the wayside due to lack of updates. Thanks to the kind folks at the Advanced Research Corp., SATAN is back, in the form of the Security Auditor's Research Assistant (SARA), a kinder, gentler, easier to use, and more updated auditing tool.
Installing SARA is simple. As long as you've got Perl and a Web browser, you're good to go. In fact, SARA even runs on Windows 2000/XP via a customized coLinux installation. Let's play it safe, though, and stick with the *nix version. Just download, extract the tarball, and perform the customary ./configure; make; make install as root. Launch SARA as root with the command /usr/local/sara/sara. Those who fear the command line can relax; the rest is done through your Web browser.
SARA can take advantage of other open source software. If it detects nmap, you can choose to use it as the engine for port scanning instead of SARA's built-in engine. This allows SARA to utilize nmap's operating system detection feature in its reports. Start SARA with the -n option to enable nmap.