Fast [SYN], [FIN, ACK] to port 80 with no data

[Marc Cozzi <cozzi () nd edu>]

I am observing IP hosts on a network here that are opening
connections [SYN], to port 80(http) on remote systems then
immediately closing [FIN,ACK] the connection or usually within
about 90ms. Then again within a min or so, repeat. It
also seems there is zero data exchanged between the connected
systems. I'm guessing it is a status polling application
that is determining if a remote system is up or down.
Probably not a necessary activity on the network and possibly
interpreted by remote network managers as scans/probes/mapping
attempts.

Question is:
Is there a way to detect, within snort, this rapid opening and
closing of remote port 80 and fire off an alert. Also, maybe
fire off a block of the remote system?

Thanks for any ideas.


  --marc



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