Snort mailing list archives

Re: snort 1.8 rules


From: Phil Wood <cpw () lanl gov>
Date: Thu, 24 May 2001 15:40:36 -0600


Opps, I just got my own message.  I meant to say that
the rule should be looking for source ports 1024 and greater.

Otherwise it becomes a giant falsepositive generator when a source port
is 80 or something like that.

I guess the source port could be changed to:

   !:1023

or

   1024:

Is that right?

On Thu, May 24, 2001 at 02:33:06PM -0600, Phil Wood wrote:

Folks,

It appears that a rule like:

alert TCP $INTERNAL :1024 -> $EXTERNAL any (msg: "ddos-shaft-synflood-outgoing"; seq: 674711609; flags: S; reference: 
arachnids,253;)

or

alert tcp $EXTERNAL :1024 -> $INTERNAL any (msg: "DDOS shaft synflood incoming"; flags: S; seq: 674711609; reference: 
arachnids,252; classtype: attempted-dos;)

will cat packets like:

       10.0.0.0:1024 -> 1.2.3.4:37123

I think the intent of the rules was to look for source ports LESS than 1024.

Thanks,

Phil

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-- 
Phil Wood, cpw () lanl gov


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