Another device using my IP address-who?

Don T wrote:
I went into Bonjour and discovered that the only device using that IP address is my Brother HL-4070CDW wireless printer.

Is that printer configured to obtain its IP address via DHCP? If not, it should be.

I have a similar problem since upgrading to 10.6.4. Frequently when I wake up my MBP it complains. It is on a home WiFi network with an airport extreme bridging to a Billion modem router. The Billion is handling the IP's. There are half a dozen or so devices in the house. No iPad. I did have it running with a manually assigned IP but switched to DHCP so it can go and find another one.

Anyone else getting this?

Michael

michael.murray wrote:
I have a similar problem since upgrading to 10.6.4. Frequently when I wake up my MBP it complains. It is on a home WiFi network with an airport extreme bridging to a Billion modem router. The Billion is handling the IP's. There are half a dozen or so devices in the house. No iPad. I did have it running with a manually assigned IP but switched to DHCP so it can go and find another one.

Anyone else getting this?

Michael

What is your problem? You changed from a manually assigned IP Address to one assigned via DHCP. Does it still report another device using the same IP Address? The problem with using a dual (DHCP and Manually) assigned IP Addresses in the same network is that whoever is manually assigning IP Addresses forgets to ensure the manually assigned address is outside the scope of the DHCP range of addresses. So eventually the DHCP server assigns the same address already assigned manually. The DHCP server has no idea that someone is manually assigning IP Addresses that have been reserved and placed within the scope of the DHCP server.

And, you should only have one device performing as a DHCP server on your network. Disable DHCP services on other devices that may be serving up addresses.

Message was edited by: BobTheFisherman

Thanks Bob. I understand that problem and assumed that was what was going on. It seems strange I should have any problems at all once I turned on DHCP. I would have thought it would just ask for another IP when I woke it from sleep without whinging to me about it!

Michael

Don T wrote:
The setup wizard works by finding the ssid, then asking to confirm the type: wpa, none, etc. It then sets up it's own IP address. I'm assuming it does so through DHCP.

If it's "setting up its own IP address", it may not be using DHCP. If that's the case, then that printer offers a poor set of configuration options.

I am getting this problem too - message popping up saying another computer is using this IP address (DHCP assigned) then in a second or two I am connected presumably to an available address. Happens fairly frequently. I just ignore it since it hasn't prevented any of our computers getting online or staying online. But, last week, my MobileMe iDisk appeared on another computer (accessing MobileMe simultaneously as showing a friend how to use iDisk - but he was entering his own username and password and got my account. Now I am worried about this DHCP thing. Are my settings wrong? What should they be to avoid this? It has always happened now and again, not just since Snow Leopard.

Help much appreciated.

Forgot to say, I am using an AEBS, spaceship type.

Hi folks,

I'm having the same problem(s), but to be honest, I have been having these problems for a good while now i.e. using Leopard and now Snow Leopard. Also, occasionally a Windows computer on my LAN would hijack my Mac's IP address I would return to my Mac with the message "os x "another device on the network is using your computer's IP address". I'm pretty sure that I was using a different wireless router at the time too, so for the problem to have persisted across two different router brands (Belkin and Netgear) suggests a lingering problem with OS X.

This should come as no surprise as OS X's wifi connectivity is notoriously patchy, so presumably as/when connections are dropped, the router releases that IP address and issues the IP address to the next device requiring it. (It's a brokering service, nothing more.) Then when the original computer regains connectivity, it finds that the IP address is taken, panics, and OS X switches to 'Self Assigned IP' address. In my case, this was 192.254.34.66. (See your Airport network settings the next time it happens to see if you experience the same.)

I've tried renewing the DHCP lease, but no luck. Even a restart sometimes doesn't fix it. So, once this setting has stubbornly taken hold, it means manually restarting the router, or switching off both machines competing for the same IP address, then starting them one after the other (a few minutes apart), hoping that they'll sensibly accept different IP addresses. Interestingly, the two competing devices at the moment are my Mac and my iPad. (The iPad has the most patchy wifi connectivity of all Apple's product line and that's really saying something.)

As a workaround for the time being, since I rarely travel with my Macbook, I've issued it a static IP address to prevent the problem happening, but a Mac is an expensive machine and I shouldn't have to resort to such workarounds.

That's my assessment, anyhow.

MrLinguaFranca.

MrLinguaFranca wrote:
Hi folks,

I'm having the same problem(s), but to be honest, I have been having these problems for a good while now i.e. using Leopard and now Snow Leopard. Also, occasionally a Windows computer on my LAN would hijack my Mac's IP address I would return to my Mac with the message "os x "another device on the network is using your computer's IP address". I'm pretty sure that I was using a different wireless router at the time too, so for the problem to have persisted across two different router brands (Belkin and Netgear) suggests a lingering problem with OS X.

I don't agree with your analysis. No one is "hijacking" your IP Address. A computer or other device on your network is using a manually assigned IP Address that is within the scope of the DHCP addresses used in your network. When you get assigned an IP Address by DHCP and that address has already been manually assigned you get the error message.

Or, when you get the error message you are really connecting to a neighbor's network and he has mannually assigned IP Addresses to devices on his network that are within his DHCP address scope. Then when you get an address from his router you get the error message.

There is no indication of a lingering OSX problem only an indication of a device manually using the same ip address that is being assigned by DHCP.

This should come as no surprise as OS X's wifi connectivity is notoriously patchy, so presumably as/when connections are dropped, the router releases that IP address and issues the IP address to the next device requiring it. (It's a brokering service, nothing more.) Then when the original computer regains connectivity, it finds that the IP address is taken, panics, and OS X switches to 'Self Assigned IP' address. In my case, this was 192.254.34.66. (See your Airport network settings the next time it happens to see if you experience the same.)

Again I disagree. OSX wifi connectivity is not "notoriously patchy". 192.254.34.66 is not a "self assigned" address and in fact it is not even in the private address range assigned by your router.

I've tried renewing the DHCP lease, but no luck. Even a restart sometimes doesn't fix it. So, once this setting has stubbornly taken hold, it means manually restarting the router, or switching off both machines competing for the same IP address, then starting them one after the other (a few minutes apart), hoping that they'll sensibly accept different IP addresses. Interestingly, the two competing devices at the moment are my Mac and my iPad. (The iPad has the most patchy wifi connectivity of all Apple's product line and that's really saying something.)

As a workaround for the time being, since I rarely travel with my Macbook, I've issued it a static IP address to prevent the problem happening, but a Mac is an expensive machine and I shouldn't have to resort to such workarounds.

This is likely why you are getting the error. The static IP Address you used is likely interfering with another device on your network.

That's my assessment, anyhow.

That's my assessment, anyhow. 🙂

MrLinguaFranca.

Bob,

With all possible respect, perhaps fisheries is more your thing. I used the term 'hijacking' ought of frustration - I don't actually mean another computer is up to some unspeakable evil.

I administer all the devices I mentioned and rest assured, they're all using DHCP. And I check the SSID of whichever network I'm connected to, so my devices are NOT connected to a neighbour's network.

Lastly, I said I assigned my Mac a static IP address BECAUSE of these DHCP issues i.e. as a "workaround". If you look up the word 'workaround' in the dictionary, you'll see that what it is - a measure taken to circumvent an unwanted issue. (By definition, a workaround cannot be the cause.)

If you're not aware of the wifi connectivity issues with a swathe of Apple products, lucky you - welcome to the party.

MrLinguaFranca wrote:
Bob,

With all possible respect, perhaps fisheries is more your thing. I used the term 'hijacking' ought of frustration - I don't actually mean another computer is up to some unspeakable evil.

I administer all the devices I mentioned and rest assured, they're all using DHCP. And I check the SSID of whichever network I'm connected to, so my devices are NOT connected to a neighbour's network.

Lastly, I said I assigned my Mac a static IP address BECAUSE of these DHCP issues i.e. as a "workaround". If you look up the word 'workaround' in the dictionary, you'll see that what it is - a measure taken to circumvent an unwanted issue. (By definition, a workaround cannot be the cause.)

If you're not aware of the wifi connectivity issues with a swathe of Apple products, lucky you - welcome to the party.

Removed comment, not worth it.
Good luck getting your issue resolved.

Message was edited by: BobTheFisherman

I'm getting this but I'm getting a cycled of these messages, each showing a different IP address. It's as if the machine is working through a list from the DHCP and noting each one as a match.

I'm using Win 7 on Parallels and I wondered whether there was some sort of conflict there?