Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

[Snort-users] Rule for initial TCP SYN packet

138 views
Skip to first unread message

Thomas Hyslip

unread,
Jan 9, 2014, 10:51:15 AM1/9/14
to
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;)

BTW, this is not for production, just doing some research on a topic.

Thanks
tom

Markus Lude

unread,
Jan 9, 2014, 1:56:11 PM1/9/14
to
On Thu, Jan 09, 2014 at 10:51:15AM -0500, Thomas Hyslip wrote:
> Hi,

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; ?

Regards,
Markus


------------------------------------------------------------------------------
CenturyLink Cloud: The Leader in Enterprise Cloud Services.
Learn Why More Businesses Are Choosing CenturyLink Cloud For
Critical Workloads, Development Environments & Everything In Between.
Get a Quote or Start a Free Trial Today.
http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk
_______________________________________________
Snort-users mailing list
Snort...@lists.sourceforge.net
Go to this URL to change user options or unsubscribe:
https://lists.sourceforge.net/lists/listinfo/snort-users
Snort-users list archive:
http://sourceforge.net/mailarchive/forum.php?forum_name=snort-users

Please visit http://blog.snort.org to stay current on all the latest Snort news!

Thomas Hyslip

unread,
Jan 9, 2014, 3:09:22 PM1/9/14
to
HI Markus, 

Thanks for the suggestion, but still doesn't work. I also tired, flags:S,CE;

Tom
  

0 new messages