I work on lan.. but on this lan many users use net-cut(available for windows) to increase there speed on lan. i want the solution to it. i want netcutdefender(available for windows) equivalent software on linux.

Are you talking about this software net-cut ? http://www.softrecipe.com/Internet/N...es/netcut.html

In my opinion no regular user has to temper with this software on his computer if it is not the admin. Restrict the users not the software they use.

You need to talk with your network administrator or change your provider. It is not safe to use network where everybody can use arp poisoning and admin will not react. To partialy defend against this tool you need to set static arp entry for your gateway and DNS servers if they are in the same LAN:First is gateway IP and second its MAC. You need to somehow get its real MAC address, maybe wireshark will be helpful. But many depends on network admin, it has ability to prevent this, for example in my country this can be punished by law.