| 摘要 |
A DNS server filter comprising a packet receiving section for receiving an inquiry from a terminal or a DNS server in a DNS protocol and a response packet from a DNS server, a session management section for managing inquiries and response packets for an entire control having a session management table for managing inquiry requests, a packet verification section for verifying whether the inquiry and the response packet are abnormal, a request generating section for generating an inquiry packet to the DNS server, a response generating section for generating a response packet returned to a transmission source of the inquiry packet, and a packet transmitting section for transmitting the inquiry and the response packet, wherein contents of the received DNS packet are checked that there is no abnormality before the received DNS packet is transmitted to the DNS server and an error response packet is generated and returned to a request source if an abnormality is detected.
|
