The options to the tcpdump command ensure that it provides enough information about the DHCP packets (which use the bootpc protocol) to enable dhcpdump to interpret the information, as you can see in Listing 20-3. This pipes output from tcpdump (which is capable of examining raw network packets) through dhcpdump, which analyzes and formats those packets to show their meaning. Tcpdump -lenx -s 1500 port bootpc |dhcpdump The dhcpdump command, also provided in the dhcp-tools package, filters DHCP-related information from packet capture information retrieved by the tcpdump command using a command such as the following: You can use the dhcpdump command to obtain more detailed information about DHCP traffic on your network. For more details of how to use this tool, see the man page. Roughly this means: "Is the server (-s) 192.168.1.254 willing to provide the address 192.168.1.66 to the client (-c) with hardware address (-h) 00:15:C5:0C:2F:5A?" In this case, the reply was affirmative. If clients cannot contact the DHCP server, the dhcping utility that is part of the dhcp-tools package may be useful.
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