Patent ID: 8477804

Claim:
A device connected to a source device and a destination device, the source device requesting TCP connection to the destination device, comprising: a processor coupled to a memory and wherein the memory further comprising: a TCP connection status database holding information of the source device, information of the destination device, and a TCP connection status between the source device and the destination device; a function of receiving an ICMP or an ICMPv6 packet sent from the source device toward the destination device, which has a type field identifying a type of the packet and a code field identifying a content of the packet; a function of converting a first value of the code field in the ICMP or the ICMPv6 packet whose code field indicates a soft error, to a second value of the code field indicating a hard error, with reference to the TCP connection status database, when the TCP connection status between the source device and the destination device is SYN SENT or SYN RECEIVED; a function of sending the converted ICMP or ICMPv6 packet having the second value of the code field indicating the hard error to the source device, which is converted from the ICMP or ICMPv6 packet having the first value of the code field indicating the soft error; and a function of recording a number of times non-converted packets are sent to the source device, wherein when the number of times exceeded to a preset number, the device converts a first value of the code field in the ICMP or the ICMPv6 packet whose code field indicates a soft error, to a second value of the code field indicating a hard error, according to the TCP connection status and sends the converted packet to the source device.