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(DHCP) I don't receive REQUEST packet

Hello everyone,
I'm writing a simple DHCP server for a ARM microprocessor.
I directly connected it with a Win PC by an Ethernet cable: the PC acts as a DHCP client.
After some seconds I receive (4!) DISCOVER packet(s).
I reply with OFFER packet where I send an IP.
The server has IP = 192.168.5.201.
It is offering the IP = 192.168.5.202.

This is the Wireshark dump:

Image @ Dump

Why the client is not requesting the REQUEST packet?

Thanks

SteMMo's avatar
3
SteMMo
asked 2018-07-26 14:03:26 +0000, updated 2018-07-26 14:07:34 +0000
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Troubleshooting via screen shot is usually an exercise in frustration because the item we want to see isn't shown. Can you upload the capture file to a public share, e.g. Cloudshark, Google Drive, DropBox etc. and amend your question with a link to the capture file?

grahamb's avatar grahamb (2018-07-26 14:19:54 +0000) edit
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Let's try with this: https://www.dropbox.com/s/hul5w0h5mnd...

SteMMo's avatar SteMMo (2018-07-26 14:28:40 +0000) edit
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Maybe it is cause the OFFER has destination = broadcast instead of the new IP? Is it yet active?

SteMMo's avatar SteMMo (2018-07-26 14:36:27 +0000) edit
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Better .. it is missing the destination MAC address (broadcast now..), is it?

SteMMo's avatar SteMMo (2018-07-26 16:01:26 +0000) edit
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This capture is not from a DHCP server on an ARM processor, unless Dell is making those. Also the client MAC address in the OFFER is wrong, and there are funny trailing bytes.

Jaap's avatar Jaap (2018-07-26 16:07:54 +0000) edit
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1 Answer

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The OFFER contains a field called Client MAC address. This is for the client to match DISCOVERS with OFFERS (among other things). In the OFFER this field is filled with the MAC address of the Server, while it has to be the MAC address of the Client the OFFER is intended for.

Jaap's avatar
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Jaap
answered 2018-07-27 04:47:14 +0000
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I confirm that the network broadcast is not a problem. Once corrected the Client MAC address field, the process is OK. Thanks

SteMMo's avatar SteMMo (2018-07-27 09:17:39 +0000) edit
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