[NBLUG/talk] Strange ethernet issue

[Steve Johnson]

Have you verified that that is not a dependency of the other?  I'm not
on a debian box (RHEL), or I would check for you.. It's possible by
installing one the other gets installed too.

-Steve


On Thu, Apr 12, 2012 at 1:47 AM,  <akleider at sonic.net> wrote:
>
> There seem to be two possible Debian packages to get the arping utility:
> arping  and
> iputils-arping
>
> Is there any reason to get the one over the other?
>
> alex
>
>> FWIW, the arp query is effectively what the system does when you run
>> ifup -- before it brings up the interface, it ARPs, and if it gets
>> responses, it doesn't bring up the iface to avoid collisions.  So
>> doing the arp might give you some idea of what the server is seeing
>> that prevents it from bringing the interface up.
>>
>> David
>>
>>
>> On Tue, Apr 10, 2012 at 3:20 PM, Steve Johnson <fratm at adnd.com> wrote:
>>> I just don't see the point in the arp query when I am sitting in the
>>> same room as all the gear and I can see what is plugged into the
>>> switch.  Is there a point that I am missing?
>>>
>>> -Steve
>>>
>>>
>>> On Tue, Apr 10, 2012 at 3:17 PM, Kyle Rankin <kyle at nblug.org> wrote:
>>>> On Tue, Apr 10, 2012 at 09:59:46AM -0700, Steve Johnson wrote:
>>>>> Yes, I physically checked the switch (Cisco switch.. not sure on
>>>>> model).. Also just to be sure I ran mmap on the IP of one the boxes
>>>>> when it was down and nothing came back.  I know pings are unreliable,
>>>>> but nmap isn't supposed to use just IMCP, so it should have detected
>>>>> something if someone got on my network.
>>>>>
>>>>> I will try the arp queries after tonights reboot.. These machines are
>>>>> production machines, so can't be down long in the middle of the day..
>>>>> :)
>>>>>
>>>>> -Steve
>>>>
>>>> Even if the machine is up, you might get interesting information from
>>>> an
>>>> arp query from a different host on the same subnet. Perform the arp
>>>> query
>>>> from a different host and confirm that you get back the MAC address you
>>>> expect.
>>>>
>>>> -Kyle
>>>>
>>>>>
>>>>>
>>>>> On Tue, Apr 10, 2012 at 9:54 AM, Kyle Rankin <kyle at nblug.org> wrote:
>>>>> > On Tue, Apr 10, 2012 at 09:40:31AM -0700, Steve Johnson wrote:
>>>>> >> Hi Guys,
>>>>> >>
>>>>> >> I am running 3 linux boxes all on the same network, running static
>>>>> 10
>>>>> >> net addresses, each on their own IP address..  A strange thing has
>>>>> >> started happening about a month ago, if I reboot the box when the
>>>>> >> system comes up at the point when it tries to bring up the eth0
>>>>> >> interface I get an error "IP Address in use by another host" and
>>>>> then
>>>>> >> the interface does not come up.  Loggin in from the console as root
>>>>> >> and running ifup eth0 gives me the same error.  The only way I can
>>>>> get
>>>>> >> the interface to come up is to physically unplug the ethernet, then
>>>>> >> run ifup eth0, that brings up the eth0 correctly, and then plug the
>>>>> >> ethernet cable back in.. Then it runs fine until another reboot (Or
>>>>> if
>>>>> >> I ifdown eth0 I will have the same problem)..
>>>>> >>
>>>>> > <snip>
>>>>> >>
>>>>> >> Ay ideas, or clues would be greatly appreciated.. I've been trying
>>>>> to
>>>>> >> trouble shoot this for over a month now with now luck.
>>>>> >>
>>>>> >> -Steve
>>>>> >>
>>>>> >
>>>>> > Are you absolutely sure that only one host truly has those IP
>>>>> addresses on
>>>>> > that subnet? When the host comes up and tries to assign the IP
>>>>> addresses to
>>>>> > itself, it will first perform an ARP and see if another MAC address
>>>>> on the
>>>>> > network claims to have that IP. What I would do is take down one of
>>>>> the
>>>>> > hosts, then from a different machine run ARP queries for those 10
>>>>> IPs
>>>>> > belonging to the first host and see if the MAC address you get back
>>>>> is the
>>>>> > correct one. If your networking guys are trying to do anything fancy
>>>>> with
>>>>> > NAT and misconfigured something, it could be that your switch is
>>>>> claiming
>>>>> > to have those IPs (it's easy to check, an arp query against one of
>>>>> the IPs
>>>>> > will return back a MAC belonging to a Cisco, HP, or whatever switch
>>>>> you
>>>>> > have).
>>>>> >
>>>>> > --
>>>>> > Kyle Rankin
>>>>> > NBLUG President
>>>>> > The North Bay Linux Users' Group
>>>>> > http://nblug.org
>>>>> > IRC: greenfly at irc.freenode.net #nblug
>>>>> > kyle at nblug.org
>>>>> >
>>>>
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>>
>> --
>> David Tomaschik
>> OpenPGP: 0x5DEA789B
>> http://systemoverlord.com
>> david at systemoverlord.com
>>
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