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Re: how to debug dhcp?



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)


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