[Snort-users] ack packets and data sequence

Matt Kettler mkettler at ...4108...
Tue Oct 26 10:46:02 EDT 2004

At 01:34 PM 10/26/2004, Jeffrey Starin wrote:
>A nice person responded to my previous query about how to track packets 
>after an alert has been triggered using the dynamic rules.  Okay, that is 
>fine, but it is also bringing in packets that just contain header 
>information and not the raw data.  I did notice that the data I am looking 
>for always has the ack bit set equal to the previous ack bit, whereas the 
>data I am not interested in always has a different ack bit sequence from 
>the previous.  So... I guess my next question would be if there is a way 
>to track only certain ack  bits and how would one actually get that bit 
>into a variable or whatever, to track?

I'd try to avoid looking at the ack sequence number (note that the ack bit 
is just that, one bit, not a number). That's too complicated at this level.

I'd try to use the dsize option instead. Bear in mind however that if your 
using stream reassembly, dsize might not work.

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