Patent ID: 8689057

Claim:
A network apparatus communicating with an external apparatus via a network, the network apparatus comprising: a reception unit configured to receive a processing request packet including a port number from the external apparatus, the processing request packet indicating that the external apparatus requests the network apparatus to perform processing; a transmitting unit configured to transmit a rejection packet including the port number to the external apparatus in response to the processing request packet, the rejection packet indicating that the network apparatus rejects a request of the external apparatus; a monitoring unit configured to monitor packets transmitted between the external apparatus and the network apparatus; a determination unit configured to determine whether an application which is specified based on the port number in the rejection packet is activated or not, in response to detecting that the rejection packet is transmitted to the external apparatus while the monitoring unit monitors the packets; and an output unit configured to, in a case where the determination unit determines that the application is not activated, output error information including information indicating the application, wherein the error information output by the output unit is different from error information which is output in a case where the application is activated.