Port Address Translation (PAT)

Port Address Translation, or PAT, is a form of Network Address Translation that allows multiple devices on a private network to communicate through a single public IP address simultaneously. A router or firewall translates the private source IP addresses and port numbers of outgoing connections into one public IP address with uniquely assigned port numbers. This mapping allows incoming response packets to be forwarded to the correct internal device and connection. PAT is therefore also known as NAT Overload. It is commonly used at the boundary between enterprise or home networks and the internet. By allowing multiple devices to share one public IPv4 address, PAT reduces the requirement for public IP addresses while providing simultaneous internet access for numerous internal devices.