How can I tell who is on my network?

Steve Lawrence February 26, 2012

Someone in my building is on my wireless network when they shouldn’t be. I’ve applied MAC filtering but I think they’ve cloned a valid MAC address. Is there any Mac OS X software I can use to show the computers and MAC addresses on the network? I’ve found utilities such as Zamzom but these are Windows only.

  1. James Bruce
    February 27, 2012 at 9:03 am

    Steve, why do you think someone is using your internet? You say they've cloned a MAC address, but youve blocked it, and they're still there? What evidence do you have of this, or is it just a hunch?

    To be completely sure, I would download a live-CD of backtrack linux, though this wont run on your mac. You should be able to run it inside a virtual machine though. Once in, put your wireless card into monitor mode and do a promiscuos scan of the network - I detailed that in "how to hack WEP" article a few months back. (//

    • Steve Lawrence
      February 27, 2012 at 10:27 am

      It's actually my son, who I've trying to stop playing games on the internet at hours he shouldn't be. I've set up a schedule on my dlink router to allow him access at certain times and then use MAC Filtering in combination with the schedule to control his access. But I know he is still online after the MAC Filtering should have kicked him off. So, either MAC Filtering isn't working know or he is using a different MAC address, but this again would presume that MAC Filtering wasn't working. That's what I'm coming down to I think. 

      • Ramski
        February 28, 2012 at 1:05 pm

        Kids nowadays

      • Lvkopykat
        February 29, 2012 at 4:04 am

        increase the physical distance between the sons equipment and the router...I.E disconect the cable from both ends at bedtime

  2. Karkala Nayak
    February 26, 2012 at 8:38 am

    Hello Steve,

    You can use IP scanner to see who is using your network 

    You can also Try Angry IP scanner 

    You can also Try internal MAC network utility
    [Broken Link Removed]

    If you want to learn about Internal IP addresses then check this site 

    I hope it helped

    • Steve Lawrence
      February 26, 2012 at 10:33 am

      I will have a look at these. Thx 

  3. Anonymous
    February 26, 2012 at 8:10 am

    You will have to log into the router/modem and see who is on it. type your router's IP address into your browser, like  or other, then go to your DHCP Table status. you should see Host Name, MAC Address, IP Address and Lease Time of all the clients connected
    to your router. 

    • Steve Lawrence
      February 26, 2012 at 9:56 am

      Yes, I've done that, but I think someone has cloned a MAC address. Although I've set up MAC Filtering and omitted that MAC address, they are still on the internet.

      • Anonymous
        February 26, 2012 at 10:36 am

        uninstall network/router driver, reboot and reinstall, check see if problem will be solved.

        Mac OS: How to release and renew a DHCP lease

        upgrade from WEP to WPA2. If your router does not have WPA2, check the manufacturer's site to see if a firmware update is available.

    • Anonymous
      February 28, 2012 at 12:39 pm

       I bet you have unsecured or secured network with WEP key. You MUST upgrade to WPA/PSK2 for best available security. I guarantee that nobody without access key will connect to your network wirelessly.

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