Definition
Port Address Translation PAT is a network address translation NAT technique that allows multiple devices on a private network to share a single public IP address. It achieves this by modifying the source port number in the outgoing packet header, creating a unique mapping between the internal device's IP address and port and the public IP address and a new port. This enables efficient use of public IP addresses and enhances network security by hiding internal network structures. For instance, a home router uses PAT to let all your connected devices access the internet using your ISP's single public IP. PAT is often confused with basic NAT, which typically translates only the IP address, not the port number. You will encounter PAT on the CompTIA Security+ and CISSP certification exams.