Cannot see the 'Offer' and 'Ack' packet with ethereal.

Glenn Satchell Glenn.Satchell at uniq.com.au
Thu Nov 16 14:42:29 UTC 2006


>Date: Thu, 16 Nov 2006 13:48:04 +0100 (CET)
>Subject: Re: Cannot see the 'Offer' and 'Ack' packet with ethereal.
>From: twanny at line.sytes.net
>To: dhcp-users at isc.org
>
>> But be aware that this isn't a fix for your problem, and it may cause
>> other problems.
>>
>> What you SHOULD be doing is one of the following :
>>
>> 1) Sniff packets on either the client or server
>>
>> 2) Use a managed switch that can mirror traffic on a port
>>
>> 3) Use a non-switched network segment (ie a hub, not a switch) that
>> the traffic has to go through.
>
>Simon,
>
>My prime objective is to flash a phone adapter. I am, first, trying to
>boot a pxeclient with grub, another machine not in the drawing. Then,
>hopefully, use what I'll learn on the phone adaptor.
>
>Do you know what's the equivalent of bootp's gerneric tags in dhcpd, I
>need this for grub?

They're called dhcp options, so man dhcp-options

Also search the dhcp archives for PXECLIENT, this has been mentioned a
few times and you should be able to find an example config.

>For you information, my setup is like this:
>
>-+------------------+------------------+----------------+-----
> |                  |                  |                |
> dns                |                  |                |
> tftp               |                  |                |
> dhcp               phone adapter      monitoring       gateway
> 192.168.123.107    192.168.123.100    192.168.123.102  192.168.123.254
> 10.0.0.7                                               10.0.0.1

If you're using a switch then you'll never see the unicast packets,
only broadcast. You need to do the packet sniffing on the dhcp server.

regards,
-glenn


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