Re: newbie - client not replying to DHCPOFFER

From: P Gentry (rdgentry1_at_cablelynx.com)
Date: 08/06/04 

Date: 6 Aug 2004 14:59:02 -0700

mellingm@supanet.com (michael melling) wrote in message news:<653057a0.0408060649.79298550@posting.google.com>...
> hi there,
>
> I did write earlier about my dhcp woes. I guess my message was far too
> long-winded. So i will cut straight to the heart of the problem.
>
> My windows98 client will not respond to the DHCPOFFER from my linux
> server. The log just says nothing after the DHCPDISCOVER and
> DHCPOFFER message and my windows winipcfg states that a DHCP server
> cannot be found.
>
> I have tested the connection successfully with a static IP address on
> the windows client and the firewall is disabled when i try with dhcpd.
>
> I am totally at a lost
>
> Any ideas?
>
> kind regards,
>
> Mike

Did see your earlier post -- it was not too long winded, rather not
winded enough.

Log files/messages are OK as a first go, but you'll almost always need
to give info from _both_ the server and the client such as nic config
params, IPs and subnets, indications that you have tried to confirm
basic network settings / performance / hardware.

You did a pretty good job -- so don't despair. It's always handy to
have a sniffer handy to watch what is "really" on the wire -- this is
where logs are insufficient. I use Ethereal since it's free and runs
well on both Linux and Windows. This way you can actually watch what
is being sent out on the network as requests and responses.

In your case, I had to double check my notes (not available) then the
Networking HOWTO. (BTW every one with Linux should have a full set of
the HOWTOs for reference.) From this:
http://www.tldp.org/HOWTO/Net-HOWTO/x1444.html
I found this (which had eluded my memory):
[quote]
Edit your /etc/rc.d/rc.local to reflect an addition of a route for
255.255.255.255.

Quoted from DHCPd README:
In order for dhcpd to work correctly with picky DHCP clients (e.g.,
Windows 95), it must be able to send packets with an IP destination
address of 255.255.255.255. Unfortunately, Linux insists on changing
255.255.255.255 into the local subnet broadcast address (in this case,
the address would be 192.5.5.223). This results in a DHCP protocol
violation. While many DHCP clients don't notice the problem, some
(e.g., all Microsoft DHCP clients) will recognize the violation.
___Clients that have this problem will appear not to see DHCPOFFER
messages from the server.___ (emphasis added)
[end quote]

There are several more lines for how you might fix this. Check it
out. Off hand I believe this is still a problem with RH9. The
sniffer (on the client) will tell you explicitly what the win client
is requesting, what the RH9 dhcpd to returning, and what (if anything)
the win client is sending back (eg., huhh? what's that?).

It's been a while since I've futzed around with this stuff, so I'll
have to reacquaint myself to be of much help. Anyway, you can find
Ethereal here:
http://www.ethereal.com/distribution/win32/
and note that you will need winpcap also.

Ethereal may seem daunting at first, but all you will need to do is to
have it record everthing to a capture file. To get Windows to send a
request to observe, with winipcfg, check your basic network settings,
release all then renew (I believe -- I'm in Linux now, so can't
readily check the exact buttons). You can easily have ethereal
display this in real time if you want to watch.

This should get you started. If you need more help, be prepared to
post your dhcpd.conf in toto, output of ifconfig and confirmatory
output of ping and traceroute when the win client is assigned a static
IP. Hopefully, the HOWTO suggestion works and that's all that's
needed.

hth,
prg
email above disabled

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