The Reply

Destination Is Restored

The NAT reply lookup restores the private destination endpoint.

highlighted = computed this step

NAT restores the private destination

The delivered destination address is 192.168.1.10 port 40000.

private port=40000\text{private port}=40000
Destination is restoredThe inbound and delivered tuples are decoded from exact bytes.Inbound reply tuple104 bits / 13 bytes0xc6336435cb007105110035f230byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711001011000000000111000100000101byte 8byte 9byte 10byte 1100010001000000000011010111110010byte 1200110000source-ip198.51.100.53destination-ip203.0.113.5protocol17source-port53destination-port62000(cont.)Delivered tuple104 bits / 13 bytes0xc6336435c0a8010a1100359c40byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711000000101010000000000100001010byte 8byte 9byte 10byte 1100010001000000000011010110011100byte 1201000000source-ip198.51.100.53destination-ip192.168.1.10protocol17source-port53destination-port40000(cont.)

Destination port changes back

Destination port changes from public port 62000 to private port 40000.

62000→4000062000\to40000
Destination is restoredThe inbound and delivered tuples are decoded from exact bytes.Inbound reply tuple104 bits / 13 bytes0xc6336435cb007105110035f230byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711001011000000000111000100000101byte 8byte 9byte 10byte 1100010001000000000011010111110010byte 1200110000source-ip198.51.100.53destination-ip203.0.113.5protocol17source-port53destination-port62000(cont.)Delivered tuple104 bits / 13 bytes0xc6336435c0a8010a1100359c40byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711000000101010000000000100001010byte 8byte 9byte 10byte 1100010001000000000011010110011100byte 1201000000source-ip198.51.100.53destination-ip192.168.1.10protocol17source-port53destination-port40000(cont.)

The server source stays the same

The source address and source port still name the server endpoint.

server port=53\text{server port}=53
Destination is restoredThe inbound and delivered tuples are decoded from exact bytes.Inbound reply tuple104 bits / 13 bytes0xc6336435cb007105110035f230byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711001011000000000111000100000101byte 8byte 9byte 10byte 1100010001000000000011010111110010byte 1200110000source-ip198.51.100.53destination-ip203.0.113.5protocol17source-port53destination-port62000(cont.)Delivered tuple104 bits / 13 bytes0xc6336435c0a8010a1100359c40byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711000000101010000000000100001010byte 8byte 9byte 10byte 1100010001000000000011010110011100byte 1201000000source-ip198.51.100.53destination-ip192.168.1.10protocol17source-port53destination-port40000(cont.)

Summary

The destination is restored to the private endpoint; the server source is preserved.

delivered destination port=40000\text{delivered destination port}=40000
Destination is restoredThe inbound and delivered tuples are decoded from exact bytes.Inbound reply tuple104 bits / 13 bytes0xc6336435cb007105110035f230byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711001011000000000111000100000101byte 8byte 9byte 10byte 1100010001000000000011010111110010byte 1200110000source-ip198.51.100.53destination-ip203.0.113.5protocol17source-port53destination-port62000(cont.)Delivered tuple104 bits / 13 bytes0xc6336435c0a8010a1100359c40byte 0byte 1byte 2byte 311000110001100110110010000110101byte 4byte 5byte 6byte 711000000101010000000000100001010byte 8byte 9byte 10byte 1100010001000000000011010110011100byte 1201000000source-ip198.51.100.53destination-ip192.168.1.10protocol17source-port53destination-port40000(cont.)