So, I’m visiting my parents for Thanksgiving. I brought my laptop with me, because I need to get some work done while I’m here. But I need to download some files off the Internet. I figured: No problem, my parents have high-speed cable internet. They even use the same provider (Comcast Cable) that I have at home. So I thought I could just unplug the ethernet cable from the back of their computer and plug it into my laptop. No dice. It has some sort of problem assigning me an IP address.
What’s the deal? Why can’t I connect, and is there any way I can fix this? (Changing some settings on my computer, for instance?)
Their ISP probably keeps a table that correlates MAC addresses with each cable modem. I had the exact same problem once. My ISP only allowed two IP addresses per installation, and when I tried to hook up a different, third computer, it wasn’t assigned an IP address.
One possible solution is to use a program like this (disclaimer, I’ve never used this program myself, so use it with caution) to spoof your MAC address to match the one from your parents’ computer. To get their MAC address, open a command prompt (on Windows XP, cmd from the run dialog under the Start Menu), and type ipconfig /all. The field called “physical address” is the MAC address.
This may not be useful to the OP, but would a router solve this problem? I’m not sure how it all works, but if you hook the cable modem into a router, and then the other computers into the router, would the cable modem only see one connection or each individual computer?
You only get 1 IP address at a time, and yes it’s corrolated to your MAC>
Unplug your cable modem for 30 seconds, then plug it back in, then re-request an IP address (called “Repair” in XP).
As a recovering Comcast support rep, I’m 99% positive this’ll solve your problem. If not, call Comcast and keep people like my former self employed.
Most likely. Every router I have used has an option to clone any arbitrary MAC address. Just set the router to have the same MAC as the parent’s computer[sup]*[/sup], and you can have as many different computers behind the router as you want.
However, it’s probably much easier to follow Nanoda’s suggestion of either unplugging the modem or calling the ISP. In fact, before I got a router, I had to use the latter method to get connected with the third computer I mentioned in my previous post.
[sup]*[/sup]The cloned MAC address will only apply to the WAN side of the network, so you won’t run into any problems that would be caused by having two identical MAC addresses on the same network should the parents wish to hook up their computer to the router.
Yep, this fixed it. I should have guessed this would be a “turn it off and turn it back on” kind of problem.
Thanks to Nanoda and all the others who replied.
Actually, I’m pretty sure the amount of time it took me to post here and get an answer was less than what it would have taken to (1) Find the customer service number, (2) navigate some unnecessarily elaborate menu system, (3) wait on hold for a million years, and (4) actually get an answer to my question.
Of course, I’m just guessing about (2) and (3), but that’s been my experience with most customer service hotlines in the past. Of course if I hadn’t gotten a quick answer here, that’s what I would have tried next.
