how to debug dhcp?

[dragoran]

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)