Re: stream4 question

[Erek Adams <erek () snort org>]

On Thu, 7 Aug 2003, Merrill, Bill (CHS) wrote:

> I have racked my brain, and cannot think of a way to filter the following
> out. I am not a programmer, and editing the header file scared me a bit.
>
> Besides fixing the problem with the terminal itself, an old Unisys LT300,
> can I actually filter the following with a rule somehow?

Yep.

[...snip...]

> [**] [111:1:1] (spp_stream4) STEALTH ACTIVITY (unknown) detection [**]
> 08/07-08:48:46.256474 x.x.x.x:2667 -> x.x.x.x:23 TCP TTL:254 TOS:0x0 ID:24
> IpLen:20 DgmLen:44
> ****P*S* Seq: 0x63  Ack: 0x0  Win: 0x572  TcpLen: 24
> TCP Options (1) => MSS: 1394

[...snip...]

There are two basic ways to ignore traffic.  Pass rules and BPF filters.
Since this is from the stream4 preprocessor, a pass rule won't help you.
You'll need to use a BPF filter.

At the most basic level, it tells Snort what traffic to or not to look at.

        snort <your options here> "not (src 10.10.10.10 and dst
10.10.10.11 and port 23)

For a more detailed breakdown, check out the tpcdump manpage [0].

Cheers!

-----
Erek Adams

   "When things get weird, the weird turn pro."   H.S. Thompson


[0]     http://www.tcpdump.org/tcpdump_man.html


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