dhcpdump(8)

1DHCPDUMP(8)                User Contributed Software               DHCPDUMP(8)
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NAME

6       dhcpdump - DHCP packet dumper
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SYNOPSIS

9       dhcpdump [-h regular-expression] [-H] -i interface
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11       dhcpdump [-h regular-expression] [-H] -r pcapfile
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DESCRIPTION

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

18       dhcpdump -i /dev/fxp0
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20       If you want to filter a specific Client Hardware Address (CHADDR), then
21       you can specify it as a regular expression:
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23       dhcpdump -i /dev/fxp0 -h ^00:c0:4f
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25       This will display only the packets with Client Hardware Addresses which
26       start with 00:c0:4f.
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28       Option -H will additionally show full packet hex dump.
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30       Instead of getting live data from an interface, a pcap dump file can be
31       used:
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33       dhcpdump -r pcapfile
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OUTPUT

36         TIME: 15:45:02.084272
37           IP: 0.0.0.0.68 (0:c0:4f:82:ac:7f) > 255.255.255.255.67 (ff:ff:ff:ff:ff:ff)
38           OP: 1 (BOOTPREQUEST)
39        HTYPE: 1 (Ethernet)
40         HLEN: 6
41         HOPS: 0
42          XID: 28f61b03
43         SECS: 0
44        FLAGS: 0
45       CIADDR: 0.0.0.0
46       YIADDR: 0.0.0.0
47       SIADDR: 0.0.0.0
48       GIADDR: 0.0.0.0
49       CHADDR: 00:c0:4f:82:ac:7f:00:00:00:00:00:00:00:00:00:00
50        SNAME: .
51        FNAME: .
52       OPTION:  53 (  1) DHCP message type         3 (DHCPREQUEST)
53       OPTION:  54 (  4) Server identifier         130.139.64.101
54       OPTION:  50 (  4) Request IP address        130.139.64.143
55       OPTION:  55 (  7) Parameter Request List      1 (Subnet mask)
56                                                     3 (Routers)
57                                                    58 (T1)
58                                                    59 (T2)
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60       At the option field, the first field is the value of the option, the
61       second one (between brackets) is the length of the option-datafield,
62       the third field is the name of the option, the fourth field is the data
63       of the option.
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RETURN VALUES

66       Always 0.
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NOTES

69       Privileged access is often needed for accessing the interface.
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BUGS

72       Not all the parameter options are printed verbose, because of lack of
73       documentation. Not all the options are tested, because of lack of
74       clients/servers with these options. If you have a dump of one of them,
75       please send them to me and I'll incorporate them.
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THANKS TO

78       Ralph Droms and Ted Lemons "The DHCP Handbook", ISBN 1-57870-137-6.
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80       Peter Apian-Bennewitz <apian@ise.fhg.de> for his Client Hardware
81       Address filtering
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AUTHOR

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