An Unexpected IP

This call happened to be for an old SCO Unix system, but really it could have been for anything: Windows, Linux, Mac OS X, it would have all been the same. An old server had an OS transplant and needed to be connected to the network.

The consultant at the other end of the phone had already run through "netconfig" (SCO's network configuration tool) without luck. I asked what kind of card it was and was told that it was an Intel Pro 1000 and that he had downloaded drivers from Intel.

I felt we ought to try the drivers from SCO's ftp site instead. I don't know that there's anything wrong with the drivers at Intel - they might be the exact same drivers for all I know - but he wasn't having any luck so far, so why not? We did, and after installing them and all that, the network still didn't work. An "ifconfig net0" showed that everything was fine, but he couldn't ping anything.

I had to ask if he was sure that everything was OK physically. No chance of a bad wire, dead switch port? No possibility of a link speed speed mismatch? No, he said, he had booted from a CD and had network connectivity. As we'll see in a moment, that couldn't have been precisely true, but when troubleshooting remotely we have to go with what we're told until we learn differently, so...

"Though that was DHCP", he said.

Hmmm. Well, OK. Maybe he's confused about the IP he's using - it could already be in use. So sure, let's try DHCP. Why not?

After that reconfiguration and reboot, I asked for an "ifconfig -a" before we tried anything and got a surprise: the ip was 172.16.12.12. Why was that a surprise? Because earlier he had been trying to assign a 172.16.2 address - dot 2, not dot 12.

That wasn't a mistype - he wanted to be on the 172.16.2 network. Obviously he was not. Apparently he was plugged into the wrong switch port. Although he was unaware of it at this time, the network was segmented using a smart switch and whatever port he was using was on the 172.16.12 section.

As he was previously unaware of that network, I now suggested that he needed to sit down with the client's IT people and find out where he really needed to plug in. He said that would probably be the server room, which makes sense: the poor machine was out of its native element. Take it home where it belongs and everything would probably be fine.

So there we left it. I showed him how to configure a default gateway and pointed him at articles for setting resolv.conf and populating /etc/hosts. That should do it.

Take Control of Upgrading to Snow Leopard

Take Control of Exploring & Customizing Snow Leopard

Jump to Comments

Many of the products and books I review are things I purchased for my own use. Some were given to me specifically for the purpose of reviewing them. I resell or can earn commissions from the sale of some of these items. Links within these pages may be affiliate links that pay me for referring you to them. That's mostly insignificant amounts of money; whenever it is not I have made my relationship plain. I also may own stock in companies mentioned here. If you have any question, please do feel free to contact me.

Specific links that take you to pages that allow you to purchase the item I reviewed are very likely to pay me a commission. Many of the books I review were given to me by the publishers specifically for the purpose of writing a review. These gifts and referral fees do not affect my opinions; I often give bad reviews anyway.

We use Google third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.