Patent ID: 7969976

Claim:
A gateway apparatus for rewriting and forwarding an application header, namely, data following a TCP header of a packet flowing over a TCP connection between terminals, comprising: a number conversion table including an entry for registering a pair of a sequence number which is expected to be contained in the TCP header of a next packet to forward and a sequence number after conversion which is obtained by considering a change in packet size due to application header rewriting as a pair of an expected sequence number and a conversion sequence number as well as a pair of an expected Ack number and a conversion Ack number contained in the TCP header of a packet in a direction opposite to that of the forwarded packet at the time of forwarding the packet; and a conversion unit for performing number rewriting process of rewriting the sequence number and the Ack number contained in the TCP header of a packet to forward to the conversion sequence number and the conversion Ack number corresponding to the expected sequence number and the expected Ack number matching these numbers by referring to the number conversion table at the time of forwarding the packet.