| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve network security, although in a traditional method, the open or close control of a network port is performed by a NAT, and in the case there is a communication terminal in which a port number automatically changes, or in an environment in which there is no NAT, network security cannot be improved. <P>SOLUTION: When a SIP session is established, it is determined whether a communication partner is able to use an object service. Only when the service can be used, an object port is opened. Even when the port is open, data from other than the device with which the SIP session is established is not received. By changing a port number used by a service every time, a port number to be used is concealed. <P>COPYRIGHT: (C)2013,JPO&INPIT |
