NAT (Network Address Translation) is a method of remapping one IP address space into another. It is primarily used to allow devices on a private network (using RFC 1918 addresses) to communicate with the public Internet using a single or few public IP addresses.
Types of NAT
- Static NAT: One-to-One mapping. Used for servers that need to be accessible from the outside.
- Dynamic NAT: Many-to-Many mapping. Maps a private IP to a public IP from a pool of available addresses.
- PAT (Port Address Translation) / NAT Overload: Many-to-One mapping. Maps multiple private IPs to a single public IP using different port numbers. This is the most common type used in homes and offices.
NAT Terminology
| Term | Description |
|---|---|
| Inside Local | The private IP address of the device on the internal network. |
| Inside Global | The public IP address the internal device uses to communicate with the outside world. |
| Outside Global | The IP address of the destination device on the internet. |
Next Step: Configure PAT in the NAT Configuration Lab.