[Snort-users] Rule for initial TCP SYN packet

Markus Lude markus.lude at ...348...
Thu Jan 9 13:56:11 EST 2014

On Thu, Jan 09, 2014 at 10:51:15AM -0500, Thomas Hyslip wrote:
> Hi,

> I'm trying to write a rule to catch the first TCP packet for new sessions
> that have the SYN flag set.  But, I'm not seeing anything.  If I remove the
> flag:S option i see everything, any suggestions? here is the rule I have
> set now.  If I craft a packet with hping3, Snort alerts, but I thought this
> would catch all new TCP connections to webpages.
> alert tcp $HOME_NET any -> any 80 (msg:"egress filter tcp traffic to port
> 80 with syn flag set"; flow: stateless; flags:S; classtype:test;
> sid:1000001; rev:1;)

does it work with  flags:S,12;  ?


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