Snort Whitelist question



  • I have a question about snort site whitelisting. I'd want an alias composed of a few sites that snort will whitelist but can't get it to work. I have successfully whitelisted aliases that use IP addresses only. The problem is that most of the sites have multiple IP's and their IP's change often. When this happens and I resolve the IP that gets blocked in the blocked/alert tab, most of the time it comes back as AWS. Anyone run into this before? Is there a simple way to allow *.example.com from within an alias in snort?



  • Sorry, but Snort does not resolve IP addresses "real time".  It only works with static IPs.  Doing lookups would be terribly expensive.  Also, the internal workings of the Snort binary require restarting the process when changes are made to preprocessors or output plugins (and the alerting/blocking module is an output plugin).

    The next upgrade of Snort to the 2.9.7.0 tree will include the new OpenAppID preprocessor engine.  This can detect applications.  Something like that may help you when it's released.

    If you are instead wanting to "not block" some addresses, I would spend my time trying to figure out why they are getting blocked.  Perhaps it's a false positive.  If so, disabling those particular rules or adding Suppress List entries would take care of it.

    Bill



  • Thanks Bill, I'll see if I can edit any additional rules or just wait for the newer version.


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