[Snort-users] "portscans" that only hit one host, one time?

Vinay A. Mahadik VAMahadik at ...6245...
Fri Aug 9 10:57:06 EDT 2002

Yes, that's a sNOACK scan (it hasn't got a ACK flag set, and is not a
series of other normal/scan types). Check the function 'CheckTCPFlags()'
towards its end in spp_portscan.c. The flag combination is definitely
weird and qualifies as a 'stealth' scan (stealth scans are not rate
based, but per packet).


"McCammon, Keith" wrote:
> [WARNING: Slightly off-topic]
> > Aug  9 11:48:39 -> xxx.yyy.zzz.66:443
> > NOACK *2U*PRS*
> I don't know much about spp_portscan internals, so I'm not sure why this was logged.  However, I'd sure as hell qualify this as a portscan.  This packet is definitely crafted to bypass a filter or elicit a response for fingerprinting or the like.
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Vinay A. Mahadik
Summer Intern
Computer Protection Program
Lawrence Berkeley National Laboratory
(510) 495 2618

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