In this paper we describe an efficient and easy to use internet stopper, which is called AINS (Automatic Internet Stopper), which uses ARP spoofing scheme. Instead of forwarding packets to router for the case of hacking, in ARP spoofing, the AINS ignores all the packets so that internet stopping operates. The AINS program needs to be installed only in manager computer that does not require additional agent program. In addition to setting manually the stopping computer list, it is able to indentify network nodes automatically by analyzing broadcasting packets. The experimental results show that less than 4 secs for spoofing interval is enough for blocking internet usage regardless the number of computers and therefore network overhead is negligible. The AINS can indentify and control network nodes not only on same subnet but also on different subnet only if they are connected onto same ethernet switch physically. It is being used for an efficient tool for controling internet usage of university computer laboratory and also for an efficient network management.