Help finding rogue mac in dhcp lease

  • I have assigned static IP addresses to al lknown computers and devices on my network, however 1 unknown keeps popping up at 1am every night! How can I track this down and identify what it is?

    the one with the dhcp issued ip address of .151

  • LAYER 8 Global Moderator

    I show that as private?

    I would suggest you sniff traffic for that mac and see what else its doing, if anything?

  • What layer 2 devices do you have on your network, ie, wireless access points, switches, etc. If they are manageable, they can usually tell you something about where that device is connected.

  • Well I found it as a total fluke…. stumbled across it

    my kids new kindle has wifi and even when turned off I guess it phones home at 1am every night

    I have no idea if any stuff I have is layer2 all my stuff is cheapo netgear 10/100 and d/link stuff

  • LAYER 8 Global Moderator

    Odd that the kindle wifi mac is listed as PRIVATE??

    Normally you can just look up the mac and get the maker, which can help you trouble shoot the issue.

    Glad you figured out what it was by accident, but if you would of sniffed you would of seen it talking to where it talks to, etc  And that should of pointed you to what device it was.

    I have a cheapo netgear switch, and its "smart" and I can view mac addresses and such, just because its cheap does not mean it can not be loaded with features.  I had picked up my GS108T for like $79, does vlans, mirror port, igmp snooping, lagg, qos, rate limiting, etc. etc.

    Next time your in the market for a switch you might want to look for a smart one, normally only a few dollars more.