Difference Between NAT and PAT

The main difference between NAT and PAT is that NAT is a process/technology where a router or similar network device translates one IP address into another IP address whereas with PAT each host on a LAN is translated to the public IP on the WAN side of the router. address, with a different port number assignment.

NAT vs. PAT

NAT slows down the process of exhausting IP address space and preserving registered public addresses. PAT conserves IP addresses by assigning a single public IP to a group of hosts with the help of different port numbers. In NAT, the occurrence of address overlaps is significantly reduced. PAT reduces vulnerabilities and security attacks. NAT increases the flexibility of connection establishment. In PAT, the private address prevents the public address from being exposed. NAT eliminates the process of renumbering addresses at the time of changing the network. PAT is also called portability, port overloading, port-level multiplexed NAT, and single-address NAT. NAT has a one-to-one or many-to-one relationship. PAT has a many to one ratio. In NAT, public IP addresses are mapped to private IP addresses. In PAT, Multiple private IP addresses are mapped to a single public IP through the use of ports. NAT is the superset of PAT. PAT is a dynamic form of NAT. Examples of NAT are static NAT and dynamic NAT. Examples of PATs are static PAT and overloaded PAT.

Comparison chart

What is NAT?

NAT stands for Network Address Translation. NAT connects two networks and maps the private (local) address to the public (global) address. The term local means that the host address belongs to an internal network and is not assigned by a network information center or service provider. The term global indicates that the address is a legal address assigned by the network information center or service provider. The public address also represents one or more local addresses to the outside world. NAT slows down the rate of exhaustion of IP address space and preserves registered public addresses. NAT has a lack of end-to-end traceability. NAT has two types which are Static NAT which maps to the global address and has a one to one relationship. The other type is dynamic NAT, which converts an unregistered IP address to a registered private IP address. NAT is the superset of PAT.

What is PAT?

PAT stands for Port Address Translation. PAT translates the private IP addresses of an internal network to the public IP address with the help of port numbers. With PAT, each host on a LAN is translated to the WAN-side public IP address of the router, but with a different port number assignment. PAT is a form of dynamic NAT through which address translation can be configured at the port level while remaining IP addresses are also optimized. PAT uses the IPv4 address along with the port number. In PAT, the private address also prevents the public address from being exposed. In PAT there is a one-to-one or many-to-one relationship. With a single IP address, you don’t run more than one type of public service. The types of PATs are static PAT and overloaded PAT.

Key differences

1. NAT improves security because the IP addresses of internal hosts are invisible while, in PAT, the private address prevents the public address from being exposed.
2. NAT along with IPv4 addressing scheme conserves IPv4 addresses and extends their lifetime, on the other hand PAT uses IPv4 address along with port number.
3. NAT is a superset of PAT, while PAT is the type of NAT.
4. In the translation process, NAT uses IP addresses, while PAT uses IP addresses along with port numbers.
5. NAT has a one-to-one or many-to-one relationship, while PAT has a many-to-one relationship.
6. NAT does not use ports, while PAT uses source ports in the translation process.
7. In NAT, the occurrence of address overlaps is significantly reduced, while PAT reduces vulnerabilities and security attacks.
8. In NAT there is a lack of end-to-end traceability, while in PAT the number of entries in the internal table is reduced to keep records of connections.

Final Thought

The NAT and PAT protocols are used to minimize the requirement for globally unique IP addresses. They both work in a similar way, there is only a small difference between them. NAT does not use ports while in PAT, all internal machines can share a single translation address.