#
# $Id: dhcpdump.pod,v 1.3 2003/11/20 11:52:59 mavetju Exp $
#

=head1 NAME

B<dhcpdump> - DHCP packet dumper

=head1 SYNOPSIS

B<dhcpdump> [B<-h> I<regular-expression>] B<-i> I<interface>

=head1 DESCRIPTION

This command parses the output of tcpdump to display the dhcp-packets for
easier checking and debugging.

=head1 USAGE

S<dhcpdump -i /dev/fxp0>

If you want to filter a specific Client Hardware Address (CHADDR), then
you can specifiy it as a regular expressions:

S<dhcpdump -i /dev/fxp0 -h ^00:c0:4f>

This will display only the packets with Client Hardware Addresses
which start with 00:c0:4f.

=head1 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.

=head1 RETURN VALUES

Always 0.

=head1 NOTES

Privileged access is often needed for accessing the interface.

=head1 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 incorperate them.

=head1 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

=head1 AUTHOR

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

=head1 SEE ALSO

dhcpd(8), tcpdump(1), RFC2132
