I noticed that my 10.6.6 box has some process sending out ICMP messages to "random" hosts, which concerns me a lot.

when doing a tcpdump icmp I see a lot of the following

15:41:14.738328 IP macpro > bzq-109-66-184-49.red.bezeqint.net: ICMP macpro udp port websm unreachable, length 36
15:41:15.110381 IP macpro > 99-110-211-191.lightspeed.sntcca.sbcglobal.net: ICMP macpro udp port 54045 unreachable, length 36
15:41:23.458831 IP macpro > 188.122.242.115: ICMP macpro udp port websm unreachable, length 36
15:41:23.638731 IP macpro > 61.85-200-21.bkkb.no: ICMP macpro udp port websm unreachable, length 36
15:41:27.329981 IP macpro > c-98-234-88-192.hsd1.ca.comcast.net: ICMP macpro udp port 54045 unreachable, length 36
15:41:29.349586 IP macpro > c-98-234-88-192.hsd1.ca.comcast.net: ICMP macpro udp port 54045 unreachable, length 36

I got suspicious when my router notified me about a lot of ICMP messages that don't get a response

[INFO] Mon Jan 10 16:31:47 2011 Blocked outgoing ICMP packet (ICMP type 3) from 192.168.1.189 to 212.25.57.90

Does anyone know how to trace which process (or worse kernel module) might be responsible for this?

I rebooted and logged in with a virgin user account and tcpdump showed the same results.

Any dtrace magic welcome.