Re: Question about searching in packet headers

[Fedor Niskov via Snort-sigs <snort-sigs () lists snort org>]

Thank you for your advice; it seems to be a good idea, but unfortunately, when I try to do it, it doesn't work - 'content' 
in an IP rule doesn't see bytes in TCP header. What version of Snort do you use (mine is 2.9.7.0)? Maybe some additional rule options 
are required?

18.10.2020 18:56, Santosh Subramanya пишет:
> Hi Fedor,
>
> To search in TCP header, you can use alert ip $EXTERNAL_NET instead of alert tcp EXTERNAL_NET.
>
> By using ip instead of tcp, snort starts searching patterns mention in signature from ip header.
>
> I hope this helps.
>
> Regards,
> Santosh
>
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> *From:* Snort-sigs <snort-sigs-bounces () lists snort org> on behalf of Fedor Niskov via Snort-sigs <snort-sigs () lists 
> snort org>
> *Sent:* Sunday, October 18, 2020 12:16:24 AM
> *To:* snort-sigs () lists snort org <snort-sigs () lists snort org>
> *Subject:* [Snort-sigs] Question about searching in packet headers
> Hello, excuse me, I have a question about Snort rules: can I do search in packet headers? I know about the 'content' option, 
> but it performs searching only in payload; however, I'd like to check presence of some byte sequences in headers.
>
> It would be useful to search in headers; for instance, I need to check some TCP options, but Snort non-payload rule options 
> don't support it; if I could search for specific bytes in TCP header, I would be able to perform these checks.
>
> (Fedor Niskov)
>
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