Since the last edition of Snort Report, Snort IDS has been updated from version 2.6.1 to 2.6.1.2. So I'll begin this edition by addressing the issue of upgrading from one version to the next. Then I'll move on to discuss the contents of the snort.conf configuration file.
In my last Snort Report, I recommended creating a directory specifically for Snort 2.6.1, namely /usr/local/snort-2.6.1. That directory contained the Snort binary, in the bin/ directory. To "upgrade," create a new directory for Snort 2.6.1.2, e.g.:
freebsd61-generic:/root# mkdir /usr/local/snort-2.6.1.2
Now proceed with the steps to retrieve, extract and compile Snort described in the previous article. Be sure to replace instances of "snort-2.6.1" with "snort-2.6.1.2". To run the new version instead of the old, invoke it from the /usr/local/snort-2.6.1.2/bin/ directory.
I recommend creating new directories for extraction and installation every time you encounter a new version of Snort. At the very least, you will have a chance to keep the old version running while creating a new version for testing. Of course, you should deploy a separate testing infrastructure independent of production systems. Keeping several versions of Snort handy on production systems, however, is a good way to roll back to an older version should a newer version seem to encounter difficulties in the field.
Snort: Understanding the configuration file
Introduction: Upgrade to Snort 2.6.1.2
The snort.conf file
Defining IP ranges of interest
Defining ports of interest
Core preprocessors
Non-dynamic preprocessors
Conclusion
About the author
Richard Bejtlich is founder of TaoSecurity, author of several books on network security monitoring, including Extrusion Detection: Security Monitoring for Internal Intrusions, and operator of the TaoSecurity blog.
