How can I find the devices that are connected to my network and using up IP addresses?
Question by Lucy /

My ISP is telling me that I have an additional MAC that is hanging up 5 IP addresses.

I have only one computer in my home, with one DSL box. I have turned off any WiFi options on my printer, but the additional MAC number he gave me is not the printer’s. He says he can’t even release them from his end and has given me additional address because of this problem. I’ve looked for MAC’s on my kid’s iPod Touch and Nintendo DS, yet these things are not connected to my computer.

I have nothing additional connected to it, so I don’t know what to do. I thought if there was a way to track down this additional MAC # he gave me, I could then find what is eating the IP addresses and not releasing them. Can someone help?

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Answers (9)
  • Lucy

    Wow, lots of feedback.  Thanks for all the advice.  I think I’m still a bit confused, however, once I’m able to set down with some quiet time and go through the steps, then it should look easier.  It may take me a while to get to this with upcoming limited time, but I’ll give it a whirl.  Will update at some point in the future!

    Thanks again,
    Lucy

    • Jeffery Fabish

      Hi Lucy,

      Did you ever find out what was usin’ up all those IP Addresses?

  • James Bruce

    I dont think this has been mentioned yet, so I thought I’d add it – MAC address are assigned by manufacturer, and by doing a search of the first however many numbers (I forget), you can find out exactly who manufactured the device – if it was Apple, or Nintendo, for instance. 

  • Anonymous

    have selected Built-in Ethernet many, given it manynames and many configurations

    http://docs.info.apple.com/article.html?path=Mac/10.5/en/8159.html

    Each device on your local network will have an individual IP address. This
    address is assigned by the router. As the data comes back from the
    internet via that one single IP address, it then routes (get it, router)
    that data to the correct individual IP addresses on the local network

  • Anonymous

    have selected Built-in Ethernet many, given it manynames and many configurations

    http://docs.info.apple.com/article.html?path=Mac/10.5/en/8159.html

    Each device on your local network will have an individual IP address. This
    address is assigned by the router. As the data comes back from the
    internet via that one single IP address, it then routes (get it, router)
    that data to the correct individual IP addresses on the local network

  • Farah Haddad

    why don’t you use the IP Scanner in the App Store

  • Lucy

    Ok, WOW Jeffery.  LOL, sounds brilliant(if I can understand it).  I will try to do as you say in baby steps.  I have this fear of messing up something.  The ping thing you mentioned, my ISP tech had me do something like that but only with, I think, their IP address.  My printer is hooked to my computer with cables, but it does have WiFi options(I don’t know much about this either) and I found a way to turn off the WiFi option, yet the MAC address listed on the back of it are not the same as the one the tech told me was holding on to 5 IP addresses. So, all though I know next to nothing, it sounds like my printer isn’t the problem. Honestly, my daughters I-pod and my son’s DS have never been hooked up to this computer at all, so I guess I’m curious as to if they even tried to use their WiFi option, would it do anything at all? I’ve asked both of them if they had attempted this in a long time and they both tell me no.  We do have a Wii but it’s not hooked up to anything but the wall electric outlet.  I am running Windows 7 as I had a computer crash that I used XP on back in Jan and had to purchase this new one. I’ve had the same ISP for nearly two years AND was using this same printer and never had any problem(even with the purchase of the new computer)until about April or May.  The ISP Tech said he’s been doing this work for many years and has never seen this problem before.  The question I forgot to ask is(hopefully not a dumb one) do any software programs have MAC addresses that could do this?  I did have to install a new version of Quickbooks and NAV to this new computer.  I often run IE and Firefox at the same time.  Another question I had is do those jump drives that you purchase at, say Staples, have MAC addresses?  I do often have one of these jump drives plugged into a USB slot in the printer but don’t have a clue how to check the properties of the jump drive deep enough(if it does have a MAC).  Just to make sure I’m clear, are you saying even running one DSL box with the WiFi turned off on my printer that someone could still be my system using it?  We do have several neighbors on the same ISP.  I know I’m asking lots more questions that you may have to go back through to answer but I’m really trying to understand(sorry if it’s overload).  So in the end if I can locate this MAC address on my computer, it WILL let me know, say if it was the I-Pod(by stating it belonged to Apple),etc. Trying to find what or who this additional MAC is, is a bit of a challenge for me.  Thanks so much for your help and advice.  I’ll check back later for another update!!

    • Jeffery Fabish

      Hi Lucy,

      First to clear up your questions, A Mac Address is only assigned to your NIC (Network Interface Card). Essentially, all hardware devices have have addresses (not Mac Addresses), however here we are only concerned about network adapters. Since it’s implemented into your Network Interface Card, re-installing the operating system (or using a different OS entirely) will not effect your Mac Address. Similarly, adding more hardware will not add more Mac Addresses to the network (Granted, those are not network interface cards). Therefor, no software has a Mac Address.

      You will only allocate more IP Addresses if another devices connects to the router. If you can, I would enable NAT (Network Address Translation) which would give every device on your network the same external IP. The nerdy detail of this isn’t important, however just know that no matter how many devices are on your network you’ll only have one external IP Address.

      If your modem is disabled, nobody can leach on your network (However this probably isn’t the best security method :). They also don’t need to have the same ISP as you do to “steal” your connection. In the hopes that we can eliminate network leaching as the issue, please secure your network (using the guide provided).

      Finding out what the offending Mac Addresses are isn’t really an issue. If you think your connection is being stolen, simply securing it should fix the issue. One tool that I found is ZamZom Network Scanner which is a graphical interfaced application, which will link a mac address to an IP Address. If you can do this, it will help in determining what that device actually is.

      Don’t worry about making any mistakes. Your router can be reset, if by altering something you loose the internet connection, in the back of your router should be a pen-shaped pinhole where you can press (sometimes up to 40 seconds) to reset your configuration to default.

      Are you being charged for each IP Address? If so, please enable NAT in your router. Your ISP could be looking at a timeline of addresses that your network has allocated. If you have a dynamic IP Address (one that changes inherently) then it’s completely normal to change IP Addresses (that’s why the thought of being charged for each one is a bit concerning), unless however, he did an active-check to see what was running during the support call, and saw 5 addresses were being used at the moment, which would bring us right back to the question.

      So read the security guide and try to get your network tightened down. If you are unable to find your router’s IP Address (I forgot to mention how) go to start -> search: “cmd.exe” without quotes and type “ipconfig” and under the adapter your currently using find “Default Gateway”, that will be your routers login address (simply navigate to that IP Address as if it were a website in your browser). Please also map the mac addresses of the devices you know you’ll need to connect to the network and write them down and compare them to what your DHCP settings say in your router.

      If this becomes too much you could install TeamViewer which is a remote-desktop application that will allow me to see your desktop. This won’t really help in gathering other systems mac addresses, but I could help you with the router.

      Don’t be afraid to ask questions!

      Helpful links:
      What is an IP Address? (How Stuff Works)
      Mac Address (Wikipedia)
      PortForward (Tons of information on specific routers)

  • Jeffery Fabish

    Hi Lucy,

    You should be able to log into your router and view the mac addresses associated with your network. To do this log into your administration panel usually at http://192.168.1.1, but it depends on your router. If it’s not that, tell me what brand your router is (D-Link, Linksys, etc) and I’ll get it for you. Alternatively you may go to What Is My Router IP Address.

    Since you’re using wireless, I’d venture to guess that someone is tapping into your connection, such as your pesky neighbors. In which case I suggest you read Aibeks article How To Secure Your Wireless Network Connection. In short, you’ll want to change the routers administrator password and enable WPA2 (most preferable) or WPA encryption.

    Once you have the list of mac addresses, you’ll want to diagnoze which system has which mac address. You can find your mac address by going back to the terminal (start -> run/search: cmd.exe) and typing “ipconfig/all” without quotes and look for “physical address”. Then look at the list and check-off (or have some other way of making sure you know that this address is valid) and move onto the next system. For your iPod go to Settings -> General -> About and you should see the Mac Address listed there.

    If you determine that some unauthorized devices are using your connection you can either use the Aibek’s guide or enable “Mac Address Filtering” and simply allow the mac addresses you know you want to access the network. This will effectively prevent them from using your DHCP server and renewing their IP Address at your expense.