dhcpdump

DHCPDUMP(8) User Contributed Software DHCPDUMP(8)

NAME

   dhcpdump - DHCP packet dumper

SYNOPSIS

   dhcpdump [-h regular-expression] -i interface

DESCRIPTION

   This command listens on a network interface to display the dhcp-packets for easier checking and debugging.

USAGE

   dhcpdump -i /dev/fxp0

   If you want to filter a specific Client Hardware Address (CHADDR), then you can specify 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.

OUTPUT

     TIME: 15:45:02.084272
       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)
     HLEN: 6
     HOPS: 0
      XID: 28f61b03
     SECS: 0
    FLAGS: 0
   CIADDR: 0.0.0.0
   YIADDR: 0.0.0.0
   SIADDR: 0.0.0.0
   GIADDR: 0.0.0.0
   CHADDR: 00:c0:4f:82:ac:7f:00:00:00:00:00:00:00:00:00:00
    SNAME: .
    FNAME: .
   OPTION:  53 (  1) DHCP message type         3 (DHCPREQUEST)
   OPTION:  54 (  4) Server identifier         130.139.64.101
   OPTION:  50 (  4) Request IP address        130.139.64.143
   OPTION:  55 (  7) Parameter Request List      1 (Subnet mask)
                                                 3 (Routers)
                                                58 (T1)
                                                59 (T2)

   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.

RETURN VALUES

   Always 0.

NOTES

   Privileged access is often needed for accessing the interface.

BUGS

   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 incorporate them.

THANKS TO

   Ralph Droms and Ted Lemons "The DHCP Handbook", ISBN 1-57870-137-6.

   Peter Apian-Bennewitz <apian@ise.fhg.de> for his Client Hardware Address filtering

AUTHOR

   Edwin Groothuis, edwin@mavetju.org (http://www.mavetju.org)