Patent ID: 9571470
Date: 2017-02-14
CPC Classifications: H04L

Claim:
1. A communication system comprising: a plurality of concentrators, a server, and a management server, which are connected via a network, wherein the management server includes: a first processor connected with a first memory storing instructions that, when executed by the first processor, causes the first processor to: allocate a plurality of IP addresses to the concentrators when the concentrators connect to the network; and store IP address management information for managing the IP addresses allocated to each the concentrators for a predetermined time, wherein the server includes: a second processor connected with a second memory storing instructions that, when executed by the second processor, causes the second processor to: manage an encryption key set between the server and a first concentrator of the concentrators to which a first IP address of the IP addresses is allocated in association with the first IP address; acquire a second IP address of the IP addresses that is allocated to the first concentrator from the management server when a check time is reached, compare the acquired second IP address with the first IP address managed by the server, and associate the encryption key associated with the first IP address with the second IP address when the first IP address and the second IP address do not match with each other as a result of the comparison so the encryption key is associated with the first IP address and the second IP address; receive encrypted packet data from the first concentrator; and decrypt the received packet data with the encryption key, and wherein the first concentrator include first concentrator includes: a third processor connected with a third memory storing instructions that, when executed by the third processor, causes the third processor to: manage the encryption key set between the server and the first concentrator in association with the first IP address allocated by the management server; hold the second IP address allocated by the management server when connecting to the network; compare the first IP address with the second IP address before encrypting and transmitting the packet data to the server, and update the first IP address associated with the encryption key with the second IP address when the first IP address and the second IP address do not match with each other as a result of the comparison; encrypt the packet data with the encryption key; and transmit the encrypted packet data to the server.