Ndiff is a tool that utilizes nmap output to identify the differences, or changes that have occurred in your environment. Ndiff can be downloaded from http://www.vinecorp.com/ndiff/. The application requires that perl is installed in addition to nmap. The fundamental use of ndiff entails combining ndiff with a baseline file. This is achieved by using the “-b” option to select the file that is the baseline with the file to be tested using the “-o” option. The “-fmt” option selects the reporting format.