Failure to acquire IP over DHCP

[jdow]

On 2012/08/30 13:19, Dale Dellutri wrote:
> On Thu, Aug 30, 2012 at 2:50 PM, Suvayu Ali <fatkasuvayu+linux at gmail.com> wrote:
>> On Thu, Aug 30, 2012 at 09:11:01PM +0200, Suvayu Ali wrote:
>>> On Thu, Aug 30, 2012 at 11:25:47AM -0500, Dale Dellutri wrote:
>>>> Could you post the output of two commands:
>>>>    # ip addr show
>>>>    # ip route show
>>>>
>>>> Do it for each of the two cases:
>>>>    1. When you cannot access the internet (and you get the internal IP
>>>> 192.168.0.114)
>>>>    2. When you can access the internet (you say that everything works
>>>> when you use
>>>> any other wall outlet).
>>>>
>>>
>>> At the moment I can't provide that for both; for case (2), when
>>> everything works on another outlet I get the following:
>>>
>>> <http://pastebin.com/fF5eSp7n>
>>>
>>
>> This is the output for case (1), when it doesn't work:
>>
>> <http://pastebin.com/DVZNuNkB>
>
> These two pastebins show that the "wall outlet" that doesn't work (case 1)
> is specialized to only allow access the 192.168.0.0/24 lan.  It's probably
> connected to a different switch (or different VLAN) than the ones that do
> work (case 2).
>
> There's no mystery unless you think that the network administrators
> have made some kind of mistake.  It looks like a policy decision.

It could even be a misconfigured managed switch directing his connection
to a wrong place.

I did notice his machine is asking for a 192.168.0.x address, perhaps
renewing his home address. Other laptops might not do that so they work.
(They might be asking for an address in the 128.141.x.x range, get denied
and get an address in the 137.138.x.x range from the second dhcp server.)

He may have unconvered two bugs at once. One is an unauthorized wireless
network somebody has connected in his office. The second is a switch that
is routing his office to the 137.138 net rather than the 128.141 net. Or
they may use a dhcp server that happens to be on the 137.138 net to serve
both the 137.138 net and the 128.141 net. They DO both route the same
here all the way through the same address:  e513-e-rbrxl-2-ne0.cern.ch
That would mean the 137.141 offer might be an artifact rather than
meaningful data. That still leaves the likely unauthorized server on the
192.168.0 net.

I'd provide the fellow who is helping you with those chunks of data and
see if they are enough clues for him.

{^_^}