A method for operating a local area network having a server and a plurality of computers. The server includes an Internet gateway for directing messages to and from the Internet. Each computer in the network has a unique IP address and a unique network adapter address associated with that computer. Each computer determines the network adapter address associated with a target IP address by broadcasting an address resolution protocol (ARP) message on the local area network. The server stores information identifying IP addresses in a foreign class corresponding to computers not configured for connection to the local area network. The server responds to each ARP having a target IP address in the foreign class by returning the network adapter address of the server in the response message and assigning an IP address associated with the local area network to the IP address of the computer sending the ARP. The server translates each outbound message originating on the local area network for a destination address in the foreign class by replacing the originating IP address in the message with the IP address assigned on the local area network. The translated message is then sent via the gateway. The sever also examines each inbound message received on the gateway for a destination IP address associated with the local area network to determine if the destination address is an IP address that has been assigned to an IP address in said foreign class. If such an assignment has been made, the server translates the destination IP address.