Difference Between NAT and PAT

Main Difference

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

NAT vs. PAT

NAT slow-downs the process of depletion of the IP address space and preserves the registered public addresses. PAT conserves IP addresses by assigning single public IP to a group of hosts with the help of different port numbers. In NAT, the occurrence of address overlaps significantly reduces. PAT lessens the vulnerabilities and security attacks. NAT increases the flexibility of connection establishment. In PAT the private address preserves the public address from being exposed. NAT removes the process of address renumbering at the time of changing the network. PAT is also called porting, port overloading, port-level multiplexed NAT and, single address NAT. NAT has a one-to-one or many-to-one relation. PAT has a many-to-one relationship. In NAT public IP addresses are mapped to private IP addresses. In PAT, multiple private IP addresses maps into a single public IP by using ports. NAT is the superset of PAT. PAT is a dynamic form of NAT. The examples of NAT are static NAT and dynamic NAT. The examples of PAT are static PAT and overloaded PAT.

Comparison Chart

NATPAT
Basics
NAT translates the private local IP to the public global IP address.PAT translates the private IP addresses of an internal network to the public IP address with the help of port numbers.
Relations
NAT is the superset of PAT.PAT is a form of a dynamic NAT.
Use
NAT uses the IPv4 address.PAT uses IPv4 address along with the port number.
Relationship
NAT has a one-to-one or many-to-one relation.PAT has a many-to-one relation.
Types
Static NAT and dynamic NAT are types of NAT.Static PAT and overloaded PAT are types of PAT.

What is NAT?

NAT stands for network address translation. NAT connects two networks and maps the private (local) address into the public (global) address. The term local signifies that the host address belongs to an internal network and not assigned by a network information center or service provider. The term global indicates that the address is a licit 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 slow-downs the rate of depletion of the IP address space and preserves the registered public addresses. NAT has a lack of end-to-end traceability. NAT has two types that are static NAT which is mapped on the global address and has a one-to-one relationship. The other type is dynamic NAT which converts an unregistered IP address into 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 router’s WAN-side public IP address but with a different port number assignment. PAT is a form of a dynamic NAT through which address translation can be configured at the port level while the remaining IP addresses are also optimized. PAT uses IPv4 address along with the port number. In PAT, the private address also preserves the public address from being exposed. In PAT there is a one-to-one or many-to-one relationship. With a single IP address, more than one same type of public service does not execute. The types of PAT are static PAT and overloaded PAT. As private addresses prevent the public addresses from being exposed, PAT lessens the vulnerabilities and security attacks.

Key Differences

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

Conclusion

NAT and PAT protocols are used to minimize the requirement of globally unique IP addresses. Both works similarly, there is just a slight difference between them. NAT does not use ports while in PAT, all internal machines can share a single translation address.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

View all posts by Harlon Moss