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Utility to trace IP conflict in the network

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  • Utility to trace IP conflict in the network

    Hi,
    I am facing a network IP conflict on my network .Is there any utility by which i can scan & see which computer/Device is conflicting with the same IP address.

    thanks
    mypass

  • #2
    Re: Utility to trace IP conflict in the network

    Hi,

    What kind of devices are talking about?
    In general, if we are talking about DHCP clients then this problem wouldn't exist (assuming the DHCP is configured properly) or it'll be bypassed.
    also with the way the MS TCP/IP stack works that should be detected with Gratuitous ARP. basically you can't manually configure a client with an existing IP configuration.
    There are some improvement on the handling of the ARP cache on the Vista and win2008 os though: http://blogs.technet.com/networking/...e-wire-up.aspx.
    I had a go with a typical IP scanner (Angry IP) and what I noticed is that when I attempted to configure the same IP address as an existing one, the scanner would not pick it up but instead would report it as dead.
    I am not sure if other IP scanners would handle this different.
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    • #3
      Re: Utility to trace IP conflict in the network

      I suppose a simple solution would be to use ARP to find the MAC address of the offending device and then trace the MAC address to a port on the switch. For instance, if you give an IP address to a device but notice that it conflicts with another IP address, remove that device's IP address, clear your arp cache ( netsh interface ip delete arpcache ), run nbtstat -A [IP address] to find the duplicate IP's MAC address, and then get into your switches to trace that MAC address to a port and from there you can physically determine what machine it is. Or you could simply shut that port down and wait until someone squawks.

      There may be some nifty tool out there than can do this in an automated fashion... or maybe it's waiting for us to develop it.
      Wesley David
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      • #4
        Re: Utility to trace IP conflict in the network

        Also not forgetting the first part of the MAC can be used to determine the device manufacturer.

        Another post on the same subject:
        http://forums.petri.com/showthread.p...925#post146925
        cheers
        Andy

        Please read this before you post:


        Quis custodiet ipsos custodes?

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        • #5
          Re: Utility to trace IP conflict in the network

          I'm running in to this issues on a network that I support. The problem is that the 2 devices that are effected are the server that is set to a static IP and the other is the Linksys router WRT54G also set to a static IP. In the event logs on the server it reported that the offending device's MAC address it the router, I was able to check this by running arp -a on the server and verified the IP to the Mac address and logging in to the router and verifying its MAC address. Now one of my issues is how can the router with a static IP for the example lets say the router is 1.1.1.1 and the server is 1.1.1.25 be reported as the conflicting system, to have it correct itself. I'm thinking that it is a problem with the Router, but I'm looking for a better way to track this issue down.

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