[NBLUG/talk] Strange ethernet issue

akleider at sonic.net akleider at sonic.net
Thu Apr 12 13:04:12 PDT 2012


On the contrary: they 'conflict' with each other.

> 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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>>
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