These are numbered for reference and not for priority. These are the sorts of tools (with one or two exceptions) that will help you detect and respond to intruders. Many of these require some commitment of brainpower and willingness to learn, but I am nevertheless very pleased to see this much innovation on the defensive side. Check these out if you have some time to check out the cool work happening (mainly) in the open source tool community. The tools do not “solve” any problems (nor should they) but can help address one or more problems you may encounter.”]
Source: https://taosecurity.blogspot.com/2011/01/seven-cool-open-source-projects-for.html