Grab UDP

tcpdump -n udp dst portrange 1-9999 -v -w capture.cap

Show icmp live

tcpdump -v icmp

Viewing dumps

tcpdump -qns 0 -A -r capture.cap

tcpdump -ttttnnr capture.cap

tcpdump -vvv -r capture.cap

tcpick -C -yP -r capture.cap

http://rationallyparanoid.com/articles/tcpdump.html