Packet filtering apparatus, packet filtering method, and computer program product

A computer program product having a computer readable medium including programmed instructions, wherein the instructions, when executed by a computer, cause the computer to perform:

• receiving a first packet from a first communication device located in a first network;
• acquiring unit acquiring sender information including at least one of security information about the first communication device and authentication information about a user of the first communication device;
• creating evaluation information indicating security evaluation of the first communication device based on an evaluation criterion for the sender information;
• adding the evaluation information to the first packet to generate a second packet;
• transmitting the second packet to a second network;
• receiving a third packet from a second communication device located in the second network;
• determining whether the evaluation information included in the third packet is higher than a security criterion, the evaluation information indicating security evaluation of the second communication device;
• deleting the evaluation information from the third packet to generate a fourth packet when the evaluation information is higher than the security criterion;
• and
• transmitting the fourth packet to the first network.