High Level Overview: Receiving

• A NAT router receives an IP packet on one of its public interfaces.

• The NAT checks if it has an application listening to the destination port

• • If so, the packet is delivered to the NAT

• If not, the NAT checks its mapping table

• If a matching entry is found, the NAT re-writes the destination IP address and port according to the mapping, and transmits the packet to the appropriate host