Filtering apparatus, method, and recording medium

A filtering method comprising:

• receiving packet data;
• attaching header information of a leading fragment packet having same fragment packet identification information as the packet data to the packet data as a pseudo header when the packet data is a fragment packet, and is not a leading fragment packet;
• searching a filter table in which a filter criterion relating to the header information, and a process to be performed when the filter criterion is satisfied are associated with each other by using the header information of the packet data as a key, and determining the process associated with the filter criterion to be satisfied by the header information of the packet data as a process to be performed with respect to the packet data;
• and
• deleting the attached pseudo header from the packet data, and performing the determined process with respect to the packet data.

A non-transitory computer readable recording medium recorded with a filtering program which causes a computer to implement:

• a receiving function of receiving packet data;
• a pseudo header attaching function of attaching header information of a leading fragment packet having same fragment packet identification information as the packet data to the packet data as a pseudo header when the packet data is a fragment packet, and is not a leading fragment packet;
• a filtering function of searching a filter table in which a filter criterion relating to the header information, and a process to be performed when the filter criterion is satisfied are associated with each other by using the header information of the packet data as a key, and determining the process associated with the filter criterion to be satisfied by the header information of the packet data as a process to be performed with respect to the packet data;
• and
• a processing function of deleting the pseudo header attached by the pseudo header attaching function from the packet data, and performing the process determined by the filtering function with respect to the packet data.