From the developer: "GFI LANguard Network Security Scanner (LNSS) is a freeware tool to audit network security and proactively secure it. LNSS scans entire networks from a 'hacker's' perspective, and analyses machines for open ports, shares, security alerts/vulnerabilities, service pack level, installed hotfixes and other NETBIOS information such as hostname, logged on user name, users etc. It does OS detection, password strength testing and detects registry issues.
"Scan reports are customizable, outputted in HTML, and can be compared to previous scans, allowing you to easily see changes in your network. LNSS also features a script engine to automate security scanning, as well as a security hotfix installer. This allows you to keep your entire windows network up to date on Microsoft security hotfixes."