Re: Bizarre arp problem with Linux Fedora 'Yarrow'

From: Robert Mitchell (robert.mitchell4_at_sympatico.ca)
Date: 03/09/04 

Date: Mon, 08 Mar 2004 20:40:10 -0500

Cameron Kerr wrote:

>Robert Mitchell <robert.mitchell4@sympatico.ca> wrote:
>
>
>
>>Running ethereal showed that all the other RH and Win boxes (and my
>>Linksys wireless gateway) BROADCAST their arp requests as expected, but
>>the new box sent them directly (frame id = 04) to ethernet physical
>>address 00:00:00:00:00:00. The response ( from the local LAN adapter I
>>believe) was ICMP destination unreachable.
>>
>>
>
>I'm currently reading the ZeroConf specs, and it seems that such a
>packet would be an ARP Probe.
>
> ``In this document, the term "ARP Probe" is used to refer to an ARP
> Request packet, broadcast on the local link, with an all-zero
> 'sender IP address'. The 'sender hardware address' MUST contain the
> hardware address of the interface sending the packet. The 'target
> hardware address' field is ignored and SHOULD be set to all zeroes.
> The 'target IP address' field MUST be set to the address being
> probed.''
>
> -- Section 1.2 "Terminology"
> http://files.zeroconf.org/draft-ietf-zeroconf-ipv4-linklocal.txt
>
>
>
Thanks Cameron. I have been able to solve my problem, but I'm not 100%
sure what was going on in the first place.

An ARP Probe is what I expected, that is a BROADCAST frame, with all 0's
in the destination, and the target IP address set. In my case, my
Fedora box was sending a frame point to point (ie. NOT Broadcast) which
is a protocol violation I believe. How it got into this state, I do not
know.

I solved the problem in 2 ways. First, I re-installed. After
re-installation Fedora started arping properly, using BROADCAST frames.
Then I discovered that my Linksys router was not passing on the arp
packets from the wired LAN devices to the wireless LAN devices, and was
not responding to ARP itself. I fixed that setting, and then ARP worked
as expected. Needless to say, a late night, but thank-you ethereal!

Rob

Relevant Pages

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