Snort mailing list archives

Re: byte_test?


From: Matt Olney <molney () sourcefire com>
Date: Sun, 2 Aug 2009 08:26:04 -0700

Reads 1 byte and does a bit-wise AND of that byte against 40. The byte read is the second byte in the packet. If the result of this operation is non-zero, then the byte_test is succesful and evaluation continues.

What this ends up meaning is that is either the fourth or sixth bit is set in the second byte if the packet, this rule option will be evaluated successfully.

Matt

Sent from my iPhone

On Jul 31, 2009, at 11:05 AM, DJ Adie <djadie80 () gmail com> wrote:

Hello,

I am having trouble figuring out what "byte_test" is looking for within a packet. Can someone explain it to me? For example:

byte_test:1,&,40,2


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