This article by All American Computer Repair will show you how to install Snort on FreeBSD.
What is Snort?
It is an open source intrusion prevention system capable of real-time traffic analysis and packet logging.
1. Login to your computer as root or elevate to su
2. First we have to compile snort form the ports tree by running this command:
make -C /usr/ports/security/snort install all
You will be asked about which support you want to add to snort here you can pick MySQL if you are going to use the server as traffic monitor or instruction detection system. For me I took the defaults only because I capture the files and export them to log file using snort –dev –l . /log then I read them with tcpdump –r. But again it really depends on your needs.
Head on over to the following link for full instructions: http://www.allamericancomputerrepair.com/Blog/Post/29/Install-Snort-on-FreeBSD