Patent ID: 7181520

Claim:
A method for filtering an Internet protocol packet in customer premise equipment connected between a personal computer and a digital subscriber line, being operated in a bridge mode, the method comprising the steps of: detecting a destination Internet protocol address by analyzing the Internet protocol packet to be transmitted to another party as a user of said personal computer accesses to an Internet through said digital subscriber line; registering said destination Internet protocol address to a predetermined allowance table; detecting a source Internet protocol address of the Internet protocol packet upon receiving the Internet protocol packet through said digital subscriber line; and checking whether said source Internet protocol address is duly registered to the allowance table for passing the corresponding Internet protocol packet through said personal computer only when said source Internet protocol address has been registered, and for blocking the corresponding Internet protocol packet when said source Internet protocol address has not been registered, said step of detecting said destination Internet protocol address further comprising the steps of: checking an Ethernet packet type upon receiving the Ethernet packet through an Ethernet link connected to said personal computer, the Ethernet packet including said Internet protocol packet to be transmitted to the other party as the personal computer user access to the Internet through the digital subscriber line; and detecting said destination Internet protocol address from an Internet protocol header that follows an Ethernet header after a predetermined offset when the Ethernet packet type is a Point-to-Point Protocol over Ethernet session stage.