Netzwerkadressübersetzung

Netzwerkadressübersetzung, often abbreviated as NAT, is a method used in networking to remap one IP address space into another. It is commonly implemented in routers to connect a private network to the internet. The primary purpose of NAT is to conserve public IP addresses by allowing multiple devices on a private network to share a single public IP address.

When a device on a private network sends a packet to a destination outside the network, the NAT router intercepts the packet. It replaces the private source IP address of the device with the router's public IP address. A port number is also typically modified to keep track of which internal device sent the packet. This modified packet is then sent to the internet. When a response packet returns from the internet, the NAT router examines the destination IP address and port. Using its internal translation table, it determines which device on the private network the packet is intended for and forwards it accordingly, replacing the public IP address with the original private IP address.

There are several types of NAT, including static NAT, dynamic NAT, and port address translation (PAT), which is the most common form. PAT allows many private IP addresses to share a single public IP address by using different source port numbers for each connection. NAT can also provide a basic level of security by hiding the internal IP addresses of devices from the external network. However, it can sometimes complicate direct inbound connections and certain network protocols.