[Snort-users] Syn Scan

James Riden j.riden at ...11179...
Thu Mar 3 14:09:48 EST 2005


"Dominic" <dominic at ...13064...> writes:

>    Hi,
>
>
>    Does snort alert on SYN scans - I have tried all others and I see the
>    alerts but nothing for a SYN scan?

Depending on your preprocessor options, a SYN (or half-open) scan will
look like this in /var/log/snort/portscan.log:

Mar  4 08:35:49 x.y.z.230:4508 -> x.y.a.169:139 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4510 -> x.y.a.170:139 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4509 -> x.y.a.170:445 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4512 -> x.y.a.171:139 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4511 -> x.y.a.171:445 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4514 -> x.y.a.172:139 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4513 -> x.y.a.172:445 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4516 -> x.y.a.173:139 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4515 -> x.y.a.173:445 SYN ******S*
Mar  4 08:35:49 x.y.z.230:4518 -> x.y.a.174:139 SYN ******S*
<snip>

Of course, this is scanning the same port across different hosts - you
may also see different ports scanned against the same host - typical
of a 'nmap -sS targethost'

That's with the following in snort.conf:

preprocessor portscan: any 30 5 portscan.log

cheers,
 Jamie
-- 
James Riden / j.riden at ...11179... / Systems Security Engineer
Information Technology Services, Massey University, NZ.
GPG public key available at: http://www.massey.ac.nz/~jriden/






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