IP Address Conflict with another system...

Over the last few days, I’ve suddenly started getting the message:

“There is an IP Address conflict with another system on the network.”

I’m using a simple home network with a Linksys wireless router. There are two laptops in the house (both Dells). I have verified that my laptop and my wife’s are on different IP Addresses (her’s .100, mine .101). My IPhone has Wi-Fi disabled.

What gives?

Do you have wireless security enabled (WEP/WPA)? Maybe somebody else is using your wireless connection.

No, I hadn’t bothered up until now. Even if they were though, wouldn’t the router just assign them their own IP? That’s what has me confused…

Just to add to my reply above. I have DHCP enabled with 50 slots open.

Only if they were using DHCP.

On most wireless routers you can log into the router and see who is connected to it. That might give you a clue where it is coming from.

Not necessarily. DHCP is a feature provided by the router so that connecting systems can be assigned an IP, if necessary. However, DHCP authentication is slipshod and unreliable in weak signal areas, and a static IP (assigned on the client machine) usually offers a better and more reliable wireless connection. As always, YMMV.

Point being - a neighbour may have found your wireless access point, but could not negotiate an IP address using DHCP, and assigned himself .100 or .101.

Your router may or may not keep a record of who’s connecting, and even then, some routers only list DHCP clients. Are you insistent on seeing if somebody’s using your Wifi?

Okay, well I just enabled WPA (AEK?) with a 64 character key. I’ll let you know how it goes…

Depending upon the terms of service with your ISP you can be held liable not only for not having an insecure wireless setup, but anything that crosses your home network as well.

Well, I guess that shouldn’t be a problem anymore. Isn’t WPA pretty secure?

Did the IP conflict go away?

Yeah, so far at least. It was really intermittment though, so I’ll know for sure in another day or so. BTW, thanks for the advice. Even if that wasn’t it, it was probably a good thing to do.

Do you have a static IP assigned to your computer (such as If so, then someone tapping into your wireless using DHCP would get that address (being the lowest) if your computer is off. Then when you turn yours on, your IP wouldn’t be available and would give that error.


Nope, both laptops use DHCP. Also, the condition was coming up at random times, while the laptop was on.

If by “secure” you mean “crackable in under 60 seconds” then yes, it’s very secure.

Well, actually what I mean is “secure enough that the average hacker won’t bother cracking it.”

I live in a single family home in an older neighborhood. There are three (maybe four) houses within hacking distance and I know three of them have their own networks.

Turning on WPA probably solved the issue. If you still have problems then make sure nothing else is connected to the network. I know you said only your two laptops are on the wireless, but do you have any devices connected with a cable? Cable box, VoIP adapter? Some of these devices come pre-set with a default IP in the 192.168 range, and you have to login to the configuration page, and change it. is fairly common for this. Also just saw for a device I had to setup at work.


Doesn’t have to be a hacker, it could be (have been) somebody unintentionally connecting to your unsecured network.

When I set up my first wireless network last summer it took me several days to realize that when I was in the front part of my house I connected to my network, but when I was toward the back of the house I was connecting to a neighbor’s unsecured network.

Sounds like you’re confusing WPA with WEP. WEP is broken, but WPA is fine. OP mentioned he turned on “AEK”, probably meaning AES (aka WPA2), which is the highest WiFi security available, and with a 64 character password, it isn’t going to be bruteforced or fall to a dictionary attack any time soon.

I have to concur with the overall cause of the problem being a rogue user.

I’m no expert but…

Do you have any other equipment that uses an IP address? Some printers and webcams connect w IP addresses.

Thanks for the correction. Yep, it’s WPA (AES) with a 64 character shared key (randomly generated at one of the key sites) and key renewal period of 3600 seconds.

As for the other suggestions, I am not aware of any other wireless devices in the house that could be requesting IP addresses.

Now for a question that honestly just occured to me. Why in the hell will my router let two people connect with the same IP? Sure seems like a damn easy thing to prevent.