In message <OF459F2104.B0AF328C-ON8525701B.00558EF8-8525701B.00561C82@mail.kals ec.com>, trainier@kalsec.com writes:
As it was already noted, you need to be very careful about how you set your IDS up, specifically if you choose snort. Snort is a very powerful tool, when used correctly. Unfortunately, when used incorrectly, it can hose your network over completely.
My suggestion, in the case that you'll use snort, is to do some extensive testing on a non-production network. Take the time to learn and understand its functionality and intended purpose.
Also figure out what you're going to do with the output. Do you have the resources to investigate apparent misbehavior? Remember that any IDS will have a certain false positive rate. Even for true positives, do you have the customer care resources to notify your users and (if appropriate) hold their hands while they disinfect their machines. --Steven M. Bellovin, http://www.cs.columbia.edu/~smb