Snort mailing list archives
Re: Variable to specify 2 networks and exclude 1 host - How?
From: Matt Kettler <mkettler () evi-inc com>
Date: Thu, 14 Jul 2005 14:04:20 -0400
Simon Yip wrote:
Thanks PaulM. That could be a solution while I hope to have something like ![IP=155.200.2.10,!$HOME_NET] I have tried my above expression in a rule but it just give me a fatal error. where HOME_NET= [155.200.2.0/24,155.200.3.0/24] My purpose is to filter out a particular type of false positives alerts created by a host (its cron job generated the alert) but I do not want to ignore all this type of alert.
Usually you wind up having to create a pass rule to ignore traffic to the single host. AFAIK there is no way to create a "range with an arbitrary hole in it" as a single specifier in snort, but your idea is a good one. You could try to rephrase the above declaration as this: ![155.200.2.10/32,!$HOME_NET] Note the removal of the "IP=" syntax and instead I'm using /32 to limit it to one IP. Snort's parser might be happier with that. For those who wonder how this could work, In theory this parses as: NOT ( 155.200.2.10/32 OR NOT HOME_NET) Which if you do a DeMorgan's theorem conversion on it you get: (NOT 155.200.2.10/32) AND (HOME_NET) However, You might wind up having snort's parser barf with that, it might not want to do anything that complex, I've never tried... Try it and see. ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- Re: Snort-users digest, Vol 1 #5192 - 5 msgs Simon Yip (Jul 13)
- Re: Re: Snort-users digest, Vol 1 #5192 - 5 msgs Paul Schmehl (Jul 13)
- RE: Re: Snort-users digest, Vol 1 #5192 - 5 msgs Paul Melson (Jul 14)
- Re: Re: Snort-users digest, Vol 1 #5192 - 5 msgs Jason Brvenik (Jul 14)
- RE: Re: Snort-users digest, Vol 1 #5192 - 5 msgs Paul Melson (Jul 14)
- Variable to specify 2 networks and exclude 1 host - How? Simon Yip (Jul 14)
- Re: Variable to specify 2 networks and exclude 1 host - How? Matt Kettler (Jul 14)
- Re: Re: Snort-users digest, Vol 1 #5192 - 5 msgs Paul Schmehl (Jul 13)