source port 0, destination 0.0.0.0

WILLIAM STEGMAN · ‎08-27-2008

I have an ASA, and an IPS, and am monitoring the segments that terminate on the inside and outside interfaces of the ASA with the IPS. I keep seeing udp and tcp sweeps coming from the outside interface of the firewall and a couple hosts on the inside. The outside IP address sweeps are probably hosts on the inside since PAT is configured, althought the timestamps don't match any alerts for the inside hosts doing the sweeps. Has anyone seen this behavior in their environment? I don't think it's a worm, but I can't find any references indicating examples of legitimate traffic matching this sort of pattern.

thank you,

Bill

Farrukh Haroon · ‎08-27-2008

This is one of the chatty signatures in the Cisco IPS. It is usually recommended to disable it for internal IPs. Or you can tune it to increase the TCP SYN threshold.

For more details have a look at this post:

http://forums.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Security&topic=Intrusion%20Prevention%20Systems/IDS&topicID=.ee6e1fc&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.2cbe4c4e/5#selected_message

Regards

Farrukh

WILLIAM STEGMAN · ‎08-28-2008

thank you