RE: frag3 alerts

["Drew Burchett" <DrewB () united-systems com>]

> From examining the packet capture, I've determined that the "offending"
traffic is an NXDomain response from a valid root server.  It's being
caused by doing reverse lookups on spam email.

 

However, the question remains, is there any way I can fine tune the
frag3 preprocessor to avoid these false positives?

 

Drew Burchett

United Systems & Software

http://www.united-systems.com

Phone:  (270)527-3293

Fax:     (270)527-3132

 

  _____  

From: snort-users-admin () lists sourceforge net
[mailto:snort-users-admin () lists sourceforge net] On Behalf Of Drew
Burchett
Sent: Monday, May 22, 2006 11:18 AM
To: snort-users () lists sourceforge net
Subject: [Snort-users] frag3 alerts

 

I am seeing a lot of frag3 Fragmentation overlap alerts with my DNS
server as the destination and a source address that reverses to a root
server.  When examining the packets, the traffic seems to be valid DNS
traffic, although it has nothing to do with any domains that I host.  Is
this some sort of attack, or is it valid traffic that is throwing false
positives?  If it is a false positive, is there any way I can fine-tune
the frag3 preprocessor to avoid these?

 

Drew Burchett

United Systems & Software

http://www.united-systems.com

Phone:  (270)527-3293

Fax:     (270)527-3132

 


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