Network Translator
Network Address and Port Address Translator
NAT
Network Address Translator
- Mapping one set of IP addresses (usually private) to another set of IP addresses (usually public).
- Used for
- Reuse IP address: Share a small pool of IP addresses with a large number of hosts
- Security: internal network is invisible to the outside
PAT
Port Address Translator
- Translate transport identifiers
- TCP and UDP port numbers, ICMP query identifiers
Example
Here is an example that shows how NAT and PAT works:
![](/note/computer-network/network-layer/network-translator/NAT_hu4ff8046c06eb34f39266bd8704a793e2_442149_70f402d2291b72a7a215851d7a66c232.png)