A communication apparatus which is capable of performing bi-directional communication via a router in a local network including one or more routers is provided. An upper segment determination section obtains address range information under an upper router which is connected on an external network side of a router to which the communication apparatus is connected. A terminal communication path holding section connects and holds a communication path to another communication apparatus in the local network. A message relay section relays a communication message from the other communication apparatus. When the terminal communication path holding section receives a first request message requesting to establish a communication path from the other communication apparatus, the terminal communication path holding section stores source address information of the received first request message, and transmit a response message to the stored source address information to establish a communication path to the other communication apparatus.