With NAT (Network Address Translation), your router translates IP addresses, whereas with PAT (Port Address Translation), ports are translated. There would be no web browsing waithout NAT or PAT.
NAT is a way to map private IP addresses, turning those into public IPs. NAT was designed in order to slow down the rate of depletion of IPv4 by letting each device have its own “private” address while using one or more registered, “public” addresses.
It provides more security and can be used for things like migrating networks, creating virtual servers, load sharing on a server, or merging networks.
Static NAT is a type of address translation that allows one public IP to be mapped to many private ones. This process can allow an enterprise server or networking device with only one physical connection on the internet, which would have otherwise been inaccessible from other networks.
Dynamic NAT is a technology that takes an unregistered IP address and translates it into a registered, public IP address. Anyone can use this pool of available addresses.
The PAT is the most popular type of NAT. It uses a dynamic mapping that takes several private IP addresses and maps them to one public address using protocols.
PAT is a variant of dynamic NAT that allows for address translation on the port level. It also optimizes remaining IP addresses by grouping them and routing them to one global address, which can be easily routed to other networks.
The total number of ports that can be used for NAT is capped at 65536. PAT preserves the original source port, so if a port has already been allocated, then it will explore other available ports and IPv4 addresses to use as well.
Difference between NAT and PAT
NAT translates the internal network’s private IP address to a public one that can be accessed by others on the internet. This is common practice in networks with an internal system that needs access to other systems or websites.
PAT is a common firewall technology that uses one IP address to represent all devices on the network.
NAT and PAT are both forms of network address translation. The difference is that NAT uses an IP to translate, whereas PAT uses a port number along with the public IP.