dhcpdump - DHCP packet dumper
dhcpdump [-h regular-expression] -i interface
This command parses the output of tcpdump to display the dhcp-packets
for easier checking and debugging.
dhcpdump -i /dev/fxp0
If you want to filter a specific Client Hardware Address (CHADDR), then
you can specifiy it as a regular expressions:
dhcpdump -i /dev/fxp0 -h ^00:c0:4f
This will display only the packets with Client Hardware Addresses which
start with 00:c0:4f.
IP: 0.0.0.0.68 (0:c0:4f:82:ac:7f) > 255.255.255.255.67 (ff:ff:ff:ff:ff:ff)
OP: 1 (BOOTPREQUEST)
HTYPE: 1 (Ethernet)
OPTION: 53 ( 1) DHCP message type 3 (DHCPREQUEST)
OPTION: 54 ( 4) Server identifier 18.104.22.168
OPTION: 50 ( 4) Request IP address 22.214.171.124
OPTION: 55 ( 7) Parameter Request List 1 (Subnet mask)
At the option field, the first field is the value of the option, the
second one (between brackets) is the length of the option-datafield,
the third field is the name of the option, the fourth field is the data
of the option.
Privileged access is often needed for accessing the interface.
Not all the parameter options are printed verbose, because of lack of
documentation. Not all the options are tested, because of lack of
clients/servers with these options. If you have a dump of one of them,
please send them to me and I’ll incorperate them.
Ralph Droms and Ted Lemons "The DHCP Handbook", ISBN 1-57870-137-6.
Peter Apian-Bennewitz <firstname.lastname@example.org> for his Client Hardware
Edwin Groothuis, email@example.com (http://www.mavetju.org)
dhcpd(8), tcpdump(1), RFC2132