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Disable the use of static IP adresses on LAN

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  • Disable the use of static IP adresses on LAN

    We've got a medium LAN (150 IPs) with a DHCP server that hands IPs only to registered devices.
    We also have empty accessable ethernet ports all around our location that must remain active.
    Our main problem is that unauthorized personal connect their laptops to the ethernet ports on the walls and since we use a standard class C IP addressing (192.168.100/24 gw most of them don't have to change anything in order to connect to our network since they have this setting work at home.

    We thought about disabling the use of static IP address but don't know if thats possible (we've got SSG-150 as our gateway and multiple HP switches).

    Another option we thought about is to have an access list at the gateway but having the thought of maintaining more then 150 lines of devices is painful mostly because we already have to maintain the DHCP list today.

    Oh and having the IP class changed is not an option, yet.

    Any thoughts shared would be wonderful, thanks.
    Last edited by arnavon; 4th July 2007, 16:03.

  • #2
    Re: Disable the use of static IP adresses on LAN

    Probably not an option as it is a bit of work to setup (unless Rems can come up with a script) is setup Reservations in DHCP. If a laptop is connected that doesn't have a reserved IP then it doesn't get one and therefore no connection. I will have to look at DHCP but it may be possible to give unauthorised devices and IP but not a Default Gateway. Third party tools are also an option but don't know any off the top of my head.
    1 1 was a racehorse.
    2 2 was 1 2.
    1 1 1 1 race 1 day,
    2 2 1 1 2


    • #3
      Re: Disable the use of static IP adresses on LAN

      If someone tries to dynamically get an IP from our DHCP server it fails, but if he sets his IP manually to our network class and gateway he can easily connect and make IP collisions which happens all the time when somebody connects with one of our servers IP.
      Our DHCP server is Windows 2000 server.
      Is there any third-party software that can virtually "take" multiple IP addresses and in some way reserve them?
      Last edited by arnavon; 4th July 2007, 17:49.


      • #4
        Re: Disable the use of static IP adresses on LAN

        Just a thought, Arnavon, but there are switches that you can lock all the ports to MAC addresses. So no unauthorised laptops can get in and mess things up. Though this will achieve your objective, I realise it may not be what you want. Just thinking aloud, really.

        (Oh, and I know MAC spoofing is pretty easy).
        Best wishes,
        MCP:Server 2003; MCITP:Server 2008; MCTS: SBS2008