Patent ID: 9560058
Date: 2017-01-31
CPC Classifications: H04L

Claim:
1. A monitoring device to operate as a first monitoring device in a network including a plurality of communication devices and a plurality of monitoring devices, the monitoring device comprising: an acquisition unit configured to acquire information of packets transmitted or received by a first communication device monitored by the first monitoring device; a transmission unit configured to transmit a first join request message to a first multicast group in which a second monitoring device performs notification of communication information of a second communication device monitored by the second monitoring device, wherein the first join request message is transmitted in response to (i) the first communication device communicating with the second communication device via intra-network communications and (ii) the first communication device subsequently communicating with an external device outside of the network after communicating with the second communication device; and a determination unit configured to determine whether the external device is performing unauthorized access to the second communication device via the first communication device, based on packets being transmitted from the second monitoring device to the first multicast group and collected from the notification of communication information corresponding to the first join request message sent by the first monitoring device.