Help with a little networking problem..

Wyldstar

A friend of mine called me today because one of the computers on his home network is having trouble connecting to the network. The network has a Linksys router acting as a DHCP server. The faulty computer can't obtain an IP address from the router or access any of the other computers using DHCP or APIPA. If an IP address is properly entered manually, however, the computer can communicate with the router and all the other networked computers. Pinging any address, even the loopback address, results in a 'Destination host unreachable' message. I'm guessing his TCP/IP stack has become corrupted somehow, but I find it interesting he can still access other computers.

All the other computers are working fine, and the computer in question is running Windows XP and TCP/IP is the only protocol installed.

My only suggestion was to unistall and re-install the TCP/IP protocol which I may do for him at some point today. Any other suggestions?

- WS

spacemancw

Well I was gonna suggest re-install TCP/IP. This question is not like one of those lovely little questions that come up on the the MS tests that always have a logical answer, like "enable bootp on the router" or "install a DHCP relay agent". This will take some trial and error.

I had a situation like this before with an OS X laptop that wouldn't get an IP, just a 164.254.x.x address. On OS X there is an option to configure using DHCP with manual IP address. I did this and it worked. I then changed back to full DHCP and all was fine. But you've already tried manual config and you can't ping ur loopback ... so I would start by re-installing and make sure it's binding to the nic. What do u get when you do an ipconfig /all?

Wyldstar

What you get doing a ipconfig /all kinda depends. If it's not configured manually, you get the typical APIPA settings (no DNS, no DHCP, no default gateway, 169.254.xxx.xxx IP address, etc). Obviously, when it's manually configured you get whatever settings you provided . Ipconfig /renew just hangs the computer, as does trying to repair the connection from network connections. At first I thought maybe it was accessing the other computers using NetBEUI or something, but he could access the router via it's IP address, and then later I discovered NetBEUI wasn't installed anyway. I didn't get him to test internet connectivity by IP address because it didn't occur to me when he called. Also didn't get him to manually add DNS servers to his TCP/IP settings, but I may do that before I re-install TCP/IP just to see what happens.

- WS

RussS

I am thinking that perhaps the Linksys router needs to be reconfigured. A client had a similar problem recently and it turned out that his router had been hacked and the configuration was changed.
The fix was to reset the settings to his original ones (good that he documented that stuff) and then change the admin password from the factory one to something secure (VERY bad that he used the factory set p/w). Also has to reinstall TCP/IP on the system he had been folling around with.