tcpdump

tcpdump filter to match DHCP packets including a specific Client MAC Address:

tcpdump -i eth3 -vvv -s 1500 '((port 67 or port 68) and (udp[38:4] = 0x00cacf12))'

tcpdump filter to capture packets sent by the client (DISCOVER, REQUEST, INFORM):

tcpdump -i eth3 -vvv -s 1500 '((port 67 or port 68) and (udp[8:1] = 0x1))'

tcpdump filter DISCOVER with ASCII-Output

tcpdump -i eth3 -vXX -s 1500 '((port 67 or port 68) and (udp[247:4] = 0x63350101))'

pipe dhcp to dhcpdump (does this work????)

tcpdump -lenx -s 1500 port bootps or port bootpc | dhcpdump

tcpdump -i eth0 -nn -s0 -v -w test.pcap port 80