Limiting closed port RST response

[Arthur Chance]

Every once in a while the nightly periodic security checks tell me I've 
got a kernel message

Limiting closed port RST response from N to 200 packets/sec

where N > 200. The problem is that it doesn't say which port was 
involved. Is there any way to find that out so I can try tracking down 
the problem? AFAICT tcpdump doesn't have a way saying "closed ports on 
this machine" as a filter.