[OT] Interesting Windows IP issue

[David Kramer]

On 01/22/2011 03:32 PM, Jerry Feldman wrote:
> On 01/22/2011 03:21 PM, Mark Komarinski wrote:
>> On 1/22/2011 10:30 AM, Jerry Feldman wrote:
>>> Yesterday at work, one of my coworkers wanted to make a presentation
>>> from his company laptop (Windows XP). For some reason his IP address was
>>> showing 192.168.x.x, not the internal company 10. address. I used my
>>> Ubuntu netbook to make sure the CAT5E cable was ok, and I certainly got
>>> a valid 10. address. We moved to another office because the lighting was
>>> better, and the same thing. We even rebooted his computer. Somehow it
>>> wanted to remain at 192.168. Our cables are plugged directly into a
>>> switch that plugs into our firewall. After a while we finally got the
>>> thing up and running on the corporate network. Note that I had even done
>>> a IPCONFIG /release and IPCONFIG /renew. I've seen this before on his
>>> previous laptop. Apparently he does something at home, but when I look
>>> at properties it shows DHCP.
>>>
>> Use ipconfig /all to verify that a lease is actually getting assigned.  
>> If it is, you may have a rogue DHCP server on your hands.
> This has happened before on his previous laptop. I think it has to do
> with the way he configured it. No one else has the same problem.

OK, here's a crazy theory.  Windows sometimes tries to "bridge" ethernet
devices so they look as one device, whether you're using wireless or
wired.  Maybe it does this via its own nat?