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  1. #11
    Just Another Geek
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    He wants wireless and the ethernet cord in and active.
    Why?!?

    turn it on, the laptop tells me there is an ip conflict.
    The message should also include the MAC address of the machine that conflicts..

    As said by others, forget netbios/wins/dns.. The problem is IP based..

    Forget DHCP either.. A DHCP server will never ever give out the same IP to different machines.. A DHCP server will also not issue an IP that's already in use (it pings the IP before giving it to a client)..
    Oliver's Law:
    Experience is something you don't get until just after you need it.

  2. #12
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    I can't give you an answer you would like for why he wants to do it that way. Suffice it to say he is a man challanged by anything that is not a shortcut on his desktop.

    That said, I have taken the advice of ignoring WINS and DHCP since I can find no record of an IP conflict in Event logs. I have however found his wired MAC address floating in IPX RIP packets that seem to be generated by an old Netware programs he never removed.

    Otherwise, I have no clue. Taking his system offline produces no Ping to the offending IP address. My Dhcp tables dont show it when it goes. nMap wont find it when the laptop is taken off line and a number of testers will laso not pick up anything on the IP WHEN the laptop is taken offline. This is why I am assuming it was WINS or something stupid where the MAc or Netbios was entered twice.
    That being said I am at my wits end and ready to kill this guy. And I am not sure where to go next with this.

    Thats the story so far, I'll update as i learn more. thanks!

  3. #13
    rebmeM roineS enilnOitnA steve.milner's Avatar
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    Just a suggestion....

    Does your company (or maybe just your boss) want a particular computer to always have the same internal IP every time it connects to the system?

    If so, or you are unsure read on....

    You can handle this is 2 ways.

    1) Assign static IPs/Subnets/Name Servers/Gateways using network setup. This is no good when the user take their laptop home/ to another site/wifi zone as it is highly unlikely that these locations will have the same network address/subnets etc. so ...

    2) Use DHCP in network setup so that the laptop gets the correct details from each of the locations visited. At the work location it is possible to setup the DHCP server so that a particular MAC address of a network card gets the same IP every time. If your boss wants the same address using both wired/wireless then is is possible to assign the same IP address to 2 different MAC addresses (One MAC for the wired network adaptor and another MAC for the wireless adaptor)

    If you are using option 2 above then if you enable both wired and wireless networking you get an IP address conflict!

    What I would suggest is you ask your boss WHY he wants to do this (& if it's the case why he needs to have the same IP address when connected to the work network). Then come & tell us the reasons.

    Remember, you should not let non IT people tell you how to solve their IT problem. Get them to tell you the problem so that the expert (you) can provide the solution.

    Steve
    IT, e-commerce, Retail, Programme & Project Management, EPoS, Supply Chain and Logistic Services. Yorkshire. http://www.bigi.uk.com

  4. #14
    rebmeM roineS enilnOitnA steve.milner's Avatar
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    Forget DHCP either.. A DHCP server will never ever give out the same IP to different machines.. A DHCP server will also not issue an IP that's already in use (it pings the IP before giving it to a client)..
    Possible, but maybe the DCHP server is the one giving the error message of IP conflict & windows is reporting it.

    Steve
    IT, e-commerce, Retail, Programme & Project Management, EPoS, Supply Chain and Logistic Services. Yorkshire. http://www.bigi.uk.com

  5. #15
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    I have IP reservations on his two IP's One on his wireless xx.xx.xx.01 and one on his wired xx.xx.xx.02
    These are taken out of the mix and assigned everytime to them. We assign static IP's b/c the old Network Admin set IP filtering on some systems, so as to allow a few people access and from a specific IP. he comes in in an hour, I'll know more soon b/c this has been a huge waste of my time so far this week.

  6. #16
    rebmeM roineS enilnOitnA steve.milner's Avatar
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    Are you able to get the wired and wireless working one at a time?
    Steve
    IT, e-commerce, Retail, Programme & Project Management, EPoS, Supply Chain and Logistic Services. Yorkshire. http://www.bigi.uk.com

  7. #17
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    Yes, one at a time there is no conflict. Run them both at the same time he gets a conflict. I have set my laptop the same, and run it with both on and no conflict. I am starting to wonder if it is becuase there is something funky with his IBM Lenovo, I say this b/c a google of the model shows that some times they do funky stuff

  8. #18
    rebmeM roineS enilnOitnA steve.milner's Avatar
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    When you boss gets in, connect them one at a time & see if the wireless & wired adaptors are getting the addresses you think they should be:


    One on his wireless xx.xx.xx.01 and one on his wired xx.xx.xx.02
    IT, e-commerce, Retail, Programme & Project Management, EPoS, Supply Chain and Logistic Services. Yorkshire. http://www.bigi.uk.com

  9. #19
    Just Another Geek
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    Imagine the following scenario:

    A DHCP server is setup to issue 192.168.0.0/24 addresses.

    Computer A uses a static IP address (no DHCP), lets say 192.168.0.10.
    It also has a firewall running blocking all incoming packets.

    Computer B uses DHCP. It does a DHCP request.

    DHCP server wants to give out 192.168.0.10. DHCP server pings the address, no response. DHCP server tells Computer B to use 192.168.0.10.

    Computer B want to use this address. When it does it pops up a message "IP Conflict".

    Viable situation?

    The popup on B should include the MAC address of A. If not, check the eventlog of B. Once you have the MAC of A you can look for it on your network and you'll know which computer is the cause of the conflict.


    Another thing just popped into my head... How about someone screwing you over?

    net send yourboss IP Conflict detected


    NB The IPX traffic should be eliminated if unused but it isn't the cause of the IP conflict. TCP/IP and IPX/SPX are 2 very different network protocols and can coexist without any problem.
    Oliver's Law:
    Experience is something you don't get until just after you need it.

  10. #20
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    I am grasping at straws at this point, that is why i brought it up.
    As for your scene you described. That scares the hell out of me. Up untill 4 days ago we had 7 servers way behind in updates, we still have no IDS and I have a boss that reamed me when I brought this stuff up.
    That said, if I sniff the network for the offending IP address shouldnt I be able to see traffic from "both" systems using the IP? And if that is the case, tracking down the other system may be something to try.
    Food for thought, thanks!

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