How can I control my LAN network under the following scenario??give me my answer any network engineer on MCSE.

I have downlink of 256kbps and have the server which bear the ip address 192.168.0.1 .and my other client in the LAN has the 192.168.0.2.3.4...... all clients can use internet throught the windows operating system and server, couple of day ago someone know my sever ip address which the other clients use as the default Gatway , as I restart my server there was an IP conflict on the network ,and someone else has keep my server ip address and therefore nobody can use the internet and find my self in very difficult situation.


please tell me any procedure in such a way so that all the clients are in my control I mean they should have to authenticate themselves from the server . please any body me??????How can I control my LAN network under the following scenario??give me my answer any network engineer on MCSE.
You seem to be saying that everyone is using a FIXED (static) IP address on your network, and someone TOOK the gateway address by some sort of idiotic mistake.





Here is what I would do. Start pulling plugs on the patch panel, until the collisions disappear. Even if I pull them all, I would keep going. Then start replacing the patch cables, until the conflict appears again. (I might use PING from a computer to the GATEWAY address, until the suspect computer is plugged back in).





If I was using DHCP, I would eliminate the gateway address from the available list, then reset the router.How can I control my LAN network under the following scenario??give me my answer any network engineer on MCSE.
i hope i will be able to give you a good solution.


to be able to give others access back use a switch (or hub)... connect the server to the switch (with no other connection to the LAN) and after you start the computer you can connect the rest of the LAN. for the server the other computer will be the one that got in after, so you will get a conflict, but the internet connection of the other clients might work.


on long term i have a simple solution for you ... DHCP. with DHCP you can give ip's and default gw to other computers as they change. if you really want to authentificate users you can use vpn's, but this will kill your server's cpu if you have many clients.
First of all check al the system and stop the full access permission.





check who changed his ip address.





warn him





and reset his ip address.





BOL





Amit
Route all your computers thru a proxy on the server. If you have admin rights to all computers set everyone static and lock the networking by restricting access to admini. This wait they cannot change the IP address for the computer.








http://www.networkingfiles.com/Proxy/Ana鈥?/a>
Look for a rogue wireless access point. Many of them use that IP address for the management interface.





If you don't have too many hosts with static IP addresses such as printers, you could just re-IP the network. Make the server 192.168.108.1 and change the DHCP scope to that network. Have all the clients reboot and they'll be back in business. You'll then have to re-IP any static hosts and reset your print queues but at least you'll be back in business.





If this isn't an option, try this. It will take some time but it will lead you to the machine that's using the server's IP address. Disconnect all patch cables at the switch. Temporarily connect one workstation to it and assign 192.168.0.1 as it's IP address. Connect the patch cords one at a time and restart the temporary workstation. When you get the IP conflict, the last patch cord you connected to the switch is the culprit. Disconnect it, set the temporary workstation back to it's correct IP address and reconnect all of the remaining patch cables and reboot the server. Trace the problem connection back to it's source and resolve the issue there.
Track the person with some tracking software, change his ip to default and ur problem is solved.
The Best way to solve this problem is to use the DHCP protocol that give every one a free IP every time they log to the network
If the users on the client PC got the permission to change the IP address of their NIC is due to the fact that, they are all logging into the client with administrator privilege!!! It s not a big problem for you, you should make the networking based on the windows domain or at least work group. Ideally domain as it is easy to manage network parameters/privileges centrally. Work group, is good if you have very few computers on the LAN. But again, you should downgrade all the users to user level and block the access to the administrator accounts in each client PC. No one would be able to change the IP of your client PC then except you.





Even Microsoft recommends running your PC on a non administrative account due to the facts that while you are running your PC as administrator, viruses and spy wares etc can get installed since only the admin has the install privileges. It is better to run the client PCs as user level