On 20 December 2010 23:28, Kenneth R Westerback <kwesterback@rogers.com>
wrote:
quoted text > On Mon, Dec 20, 2010 at 09:23:34PM +1030, Damon McMahon wrote:
>> On 19 December 2010 23:28, Kenneth R Westerback <kwesterback@rogers.com>
wrote:
quoted text >> > On Sun, Dec 19, 2010 at 10:29:56PM +1030, Damon McMahon wrote:
>> >> Greetings,
>> >>
>> >> I have a troublesome DHCP client -- a Brother MFC-9420CN multifunction
>> >> centre -- I'd like to troubleshoot. It's being assigned a lease
>> >> including IP address and gateway address by dhcpd(8), but not a subnet
>> >> mask.
>> >
>> > How do you know it is not getting a subnet mask? What does the printer
>> > say its subnet mask is?
>>
>> The printer shows a netmask of 000.000.000.000 i.e. no netmask, and I
>> can't ping or otherwise establish connectivity with the printer. Once
>> I manually specify the netmask 255.255.255.0 everything's hunky dory,
>> so it would appear the netmask isn't being acquired properly.
>>
>> >
>> > As someone else has said, capturing the conversation via tcpdump would
>> > show what the printer is asking for and what is being sent. If you have
>>
>> Yes if in doubt packet-capture is a good idea, I guess -- didn't
>> realise that tcpdump(8) can interpret DHCP which helps :-) From what I
>> can tell below, the subnet mask (SM) is being offered.
>>
>> # tcpdump -envvX -s 1500 -i xl0
>> tcpdump: listening on xl0, link-type EN10MB
>> 20:54:45.656327 00:80:77:88:8b:59 ff:ff:ff:ff:ff:ff 0030 62: snap
>> 0:0:0:81:37 sap aa ui/C len=37
>> 0000: aaaa 0300 0000 8137 ffff 0028 0001 0000 ??.....7??.(....
>> 0010: 0000 ffff ffff ffff 0453 0000 0000 0080 ..??????.S......
>> 0020: 7788 8b59 6000 0001 ffff ffff 0000 0000 w..Y`...????....
>>
>> 20:54:50.289087 00:80:77:88:8b:59 ff:ff:ff:ff:ff:ff 0800 590:
>> 0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] xid:0x56f6 flags:0x8000
>> vend-rfc1048 DHCP:DISCOVER MSZ:548 PR:SM+DG+NS+HN+DN+BR+NTP+YD+WNS+WNT
>> HN:"brothermfc" (ttl 60, id 0, len 576)
>> 0000: 4500 0240 0000 0000 3c11 7cae 0000 0000 E..@....<.|?....
>> 0010: ffff ffff 0044 0043 022c 52d2 0101 0600 ????.D.C.,R?....
>> 0020: 0000 56f6 0000 8000 0000 0000 0000 0000 ..V?............
>> 0030: 0000 0000 0000 0000 0080 7788 8b59 0000 ..........w..Y..
>> 0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0100: 0000 0000 0000 0000 6382 5363 3501 0139 ........c.Sc5..9
>> 0110: 0202 2437 0a01 0306 0c0f 1c2a 282c 2e0c .........*(,..
>> 0120: 0a62 726f 7468 6572 6d66 63ff 0000 0000 .brothermfc?....
>> 0130: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0140: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0150: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0160: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0170: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0180: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0190: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0200: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0210: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0220: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0230: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>>
>> 20:54:50.290420 00:60:08:34:91:f9 00:80:77:88:8b:59 0800 366:
>> 192.168.0.1.67 > 255.255.255.255.68: [udp sum ok] xid:0x56f6
>> flags:0x8000 Y:192.168.0.2 S:192.168.0.1 vend-rfc1048 DHCP:OFFER
>> SID:192.168.0.1 LT:86400 SM:255.255.255.0 DG:192.168.0.1
>> NS:192.168.1.1 HN:"brothermfc" DN:"office" BR:192.168.0.255
>> NTP:192.168.0.1 RN:43200 RB:75600 SMTP:192.168.0.1 [tos 0x10] (ttl 16,
>> id 0, len 352)
>> 0000: 4510 0160 0000 0000 1011 e8d4 c0a8 0001 E..`......????..
>> 0010: ffff ffff 0043 0044 014c d110 0201 0600 ????.C.D.L?.....
>> 0020: 0000 56f6 0000 8000 0000 0000 c0a8 0002 ..V?........??..
>> 0030: c0a8 0001 0000 0000 0080 7788 8b59 0000 ??........w..Y..
>> 0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0100: 0000 0000 0000 0000 6382 5363 3501 0236 ........c.Sc5..6
>> 0110: 04c0 a800 0133 0400 0151 8001 04ff ffff .??..3...Q...???
>> 0120: 0003 04c0 a800 0106 04c0 a801 010c 0a62 ...??....??....b
>> 0130: 726f 7468 6572 6d66 630f 066f 6666 6963 rothermfc..offic
>> 0140: 651c 04c0 a800 ff2a 04c0 a800 013a 0400 e..??.?*.??..:..
>> 0150: 00a8 c03b 0400 0127 5045 04c0 a800 01ff .??;...'PE.??..?
>>
>> 20:54:50.293431 00:80:77:88:8b:59 ff:ff:ff:ff:ff:ff 0800 590:
>> 0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] xid:0x56f6 flags:0x8000
>> vend-rfc1048 DHCP:REQUEST RQ:192.168.0.2 MSZ:548 SID:192.168.0.1
>> LT:86400 PR:SM+DG+NS+HN+DN+BR+NTP+YD+WNS+WNT HN:"brothermfc" (ttl 60,
>> id 1, len 576)
>> 0000: 4500 0240 0001 0000 3c11 7cad 0000 0000 E..@....<.|?....
>> 0010: ffff ffff 0044 0043 022c 6e64 0101 0600 ????.D.C.,nd....
>> 0020: 0000 56f6 0000 8000 0000 0000 0000 0000 ..V?............
>> 0030: 0000 0000 0000 0000 0080 7788 8b59 0000 ..........w..Y..
>> 0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0100: 0000 0000 0000 0000 6382 5363 3501 0332 ........c.Sc5..2
>> 0110: 04c0 a800 0239 0202 2436 04c0 a800 0133 .??..9...??..3
>> 0120: 0400 0151 8037 0a01 0306 0c0f 1c2a 282c ...Q.7.......*(,
>> 0130: 2e0c 0a62 726f 7468 6572 6d66 63ff 0000 ...brothermfc?..
>> 0140: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0150: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0160: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0170: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0180: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0190: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 01f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0200: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0210: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0220: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0230: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>>
>> 20:54:50.294450 00:60:08:34:91:f9 00:80:77:88:8b:59 0800 366:
>> 192.168.0.1.67 > 255.255.255.255.68: [udp sum ok] xid:0x56f6
>> flags:0x8000 Y:192.168.0.2 S:192.168.0.1 vend-rfc1048 DHCP:ACK
>> SID:192.168.0.1 LT:86400 SM:255.255.255.0 DG:192.168.0.1
>> NS:192.168.1.1 HN:"brothermfc" DN:"office" BR:192.168.0.255
>> NTP:192.168.0.1 RN:43200 RB:75600 SMTP:192.168.0.1 [tos 0x10] (ttl 16,
>> id 0, len 352)
>> 0000: 4510 0160 0000 0000 1011 e8d4 c0a8 0001 E..`......????..
>> 0010: ffff ffff 0043 0044 014c ce10 0201 0600 ????.C.D.L?.....
>> 0020: 0000 56f6 0000 8000 0000 0000 c0a8 0002 ..V?........??..
>> 0030: c0a8 0001 0000 0000 0080 7788 8b59 0000 ??........w..Y..
>> 0040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
>> 0100: 0000 0000 0000 0000 6382 5363 3501 0536 ........c.Sc5..6
>> 0110: 04c0 a800 0133 0400 0151 8001 04ff ffff .??..3...Q...???
>> 0120: 0003 04c0 a800 0106 04c0 a801 010c 0a62 ...??....??....b
>> 0130: 726f 7468 6572 6d66 630f 066f 6666 6963 rothermfc..offic
>> 0140: 651c 04c0 a800 ff2a 04c0 a800 013a 0400 e..??.?*.??..:..
>> 0150: 00a8 c03b 0400 0127 5045 04c0 a800 01ff .??;...'PE.??..?
>>
>> > a hub (i.e. not a switch) you can use you could also capture what is
>> > being received at the printer end.
>> >
>> > You could also simply give a machine the same MAC address as the printer
>> > (with the printer disconnected of course) and capture what it gets. If
>> > it gets a subnet then the problem would seem to be in the printer.
>>
>> Nice idea, did this and the host masquerading with the Brother's MAC
>> address acquired the subnet mask just fine. From the above can I
>> assume the problem is with the DHCP client on the Brother?
>
> It certainly looks that way to me. The SM is offered, then the
> printer does the requesite REQ, and this is ACK'd. I can't think
> of anything outside of the printer that is problematic in getting
> the SM set.
>
> The odd thing I do see is that REQ from the printer does not appear
> to include the SM. This would be the string "0104ffffff00". Other
> options also seem to be missing. It is also odd that the REQ comes
> as a broadcast. This may or may not be correct, but I would have
> expected the REQ to be point to point using the new address and
> include all the offered options. It's been a while since I looked
> at that code though. It would be interesting to capture other
> transactions and see what the REQ looks like.
>
> It would also be interesting to try to get a lease from a completely
> different source if you have one. e.g. a cable modem, home router,
> etc.
The plot thickens! I plug the Brother into a Billion ADSL router and
it acquires its subnet mask just fine :-O
So, short of inserting a transparent bridge between the Brother and
the Billion and logging the ethernet frames passing through the
bridge, is there any other way of seeing what's going on here? If not
then I've an OpenBSD bridge to install...
Looking forward to your response, I was convinced it was just a buggy
DHCP client on the Brother but now I'm not so sure...
