Patent ID: 7877476

Claim:
A network system comprising: a processor operatively coupled with a memory and network interface, wherein said network is characterized by host reachability being obtained by associating a static identifier with a network address; a first communication node operatively coupled with said processor, said first communication node configured for sending a countersign signal configured for carrying state information of a reachability checked communication node or a message comprising strings added to a reply that should be made as additional information; a map information system identifying a contractor by logging in, holding a movement history of a first communication node for the contractor and providing location information of the first communication node by the movement history or/and a present location of the first communication node; and a second communication node configured for extracting the residual part deducted from a portion of said countersign signal obtained from a first communication node, wherein the second communication node converts additional information to a form convenient for a user of the second communication node, wherein the second communication node repetitively detects state information of a first communication node, wherein the second communication nodes maintains the movement history of the first communication node, and according to said movement history, displays the result of the movement history and a present location of the first communication node.