how to debug dhcp?

[dragoran]

dragoran wrote:
> David Timms wrote:
>> dragoran wrote:
>>> dragoran wrote:
>>>> John Reiser wrote:
>>>>>> when I try to use dhcp for my network device (eth0 - forcedeth) 
>>>>>> it does
>>>>>> not get an IP with the result: failed
>>>>>>     
>>>>>
>>>>>  
>>>>>> 2) how can I debug it to find out what is causing it?
>>>>>>     
>>>>>
>>>>> Boot single-user, invoke the dhcp program from a console in 
>>>>> "non-daemon"
>>>>> mode, and watch.
>>>> how do I do this (found nothing in the man page)
>>>>>   For dhcpd, consider flags -d -tf and perhaps -play.
>>>>> Also, consider running under strace.
>>>> I am talking about dhclient not dhcpd
>>>>>   For lowest-level packet trouble,
>>>>> use a program such as tcpdump or ethereal to check what goes over 
>>>>> the wire.
>>>>>
>>>>>   
>>>> used ethreal an have not found anything that looks like an error...
>>>>
>>>
>>> this is what I get in /var/log/messages:
>>> Jul 19 09:08:39 chello062178124144 dhclient: DHCPDISCOVER on eth0 to 
>>> 255.255.255.255 port 67 interval 6
>>> Jul 19 09:08:45 chello062178124144 dhclient: DHCPDISCOVER on eth0 to 
>>> 255.255.255.255 port 67 interval 9
>>> Jul 19 09:08:54 chello062178124144 dhclient: DHCPDISCOVER on eth0 to 
>>> 255.255.255.255 port 67 interval 10
>>> Jul 19 09:09:04 chello062178124144 dhclient: DHCPDISCOVER on eth0 to 
>>> 255.255.255.255 port 67 interval 12
>>> Jul 19 09:09:16 chello062178124144 dhclient: DHCPDISCOVER on eth0 to 
>>> 255.255.255.255 port 67 interval 19
>>> Jul 19 09:09:35 chello062178124144 dhclient: DHCPDISCOVER on eth0 to 
>>> 255.255.255.255 port 67 interval 5
>>> Jul 19 09:09:40 chello062178124144 dhclient: No DHCPOFFERS received.
>>>
>>> wtf?
>>> who is broken here? should I fill a bug?
>> Can you run ethereal on the dhcp server {or a third machine} to 
>> ensure the packets get to the server ?  firewall stopping udp port 67 
>> or 68 at either end ? Slow negotiating switch or mismatched port 
>> speeds ?
>> Is the DHCP server set to be authoritative; ? Without this I believe 
>> win {for eg} tries hard to use any previous dhcp it last received, 
>> not sure about fc-whatever.
>> At the server should see:
>> DHCP Discover -> server
>> client        <- DHCP Offer
>> DHCP Request  -> server
>> client        <= DHCP ACK
>>
>> DaveT.
>>
> the problem is that I havn't any access to the server (its the ISPs 
> dhcp server)
>
any idea how to get this working? it works well on windows (same nic, 
same network)