NAT (Network Address Translation)

It’s a way to map multiple private addresses inside a local network to a public IP address before transferring the information onto the internet. All this is implemented in the router or the edge platform to connect private networks to public networks like the Internet.

With NAT, an organization needs one IP address or one limited public IP address to represent an entire group of devices as they connect outside their network. Port Address Translation (PAT) enables one single IP to be shared by multiple hosts using IP and port address translation.

NAT Types

There are three types of NAT:

• Static NAT: Static NAT maps an internal IP address to an external one on a one-to-one basis.
• Dynamic NAT: With Dynamic NAT, a firewall has a pool of external IP addresses that it assigns to internal computers as needed. Like Static NAT, this creates a one-to-one mapping between internal and external IP addresses; however, these mappings are not permanent.
• PAT: PAT is used to create many-to-one mappings between internal and external IP addresses. The firewall uses the same IP address for multiple systems but assigns a different TCP or UDP port to each. Since a single IP address can have 65,535 ports associated with it, PAT allows a single external IP address to represent thousands of devices on a private network. PAT is the application of NAT that allows IPv4 addresses to scale.