[Snort-users] Check for NO TCP Flags set?

MH procana at ...4296...
Fri May 9 12:34:08 EDT 2003

Hi Paul,

What you are looking for is: flags:0
Snort already has a rule in scan.rules
It is listed as a SCAN NULL (sid:623)
Also, the stream4 preprocessor will detect this if it is enabled (it is 
enabled by default).
You can verify this in your snort.conf file.
Look for a line that in has:   preprocessor stream4: detect_scans

Hope this helps,

At 02:39 PM 5/9/2003 -0400, Sheahan, Paul wrote:

>I know I can check for flags set using Flags:S for example. Though I was
>curious if there is a way to check for NO flags being set?. I read that this
>may be seen in illicit servers.
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