According to an aspect of an embodiment, a method of relaying by network between a plurality of terminal devices and a relay device, comprising: providing first address information corresponding to a first one of said terminal devices shared between said first terminal device and said relay device; providing second address information used by the other terminal devices than said first terminal device for accessing via said relay device said first terminal device; providing a table of said first address information and said second address information in association with each other at said relay device; and changing the content of said first address information with time, said first address information enabling said relay device to access said first device, said relay device enabling other terminal devices to access said first terminal device by converting said first and second address information in reference to said table notwithstanding changing of the content of the first address information.