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Module 6: NAT for IPv4 - Coggle Diagram

- - - - IPv6 was developed with the intention of making NAT for IPv4 with translation between public and private IPv4 addresses unnecessary. However, IPv6 does include its own IPv6 private address space, unique local addresses (ULAs).
- - - - PAT ensures that devices use a different TCP port number for each session with a server on the internet. When a response comes back from the server, the source port number, which becomes the destination port number on the return trip, determines to which device the router forwards the packets. The PAT process also validates that the incoming packets were requested, thus adding a degree of security to the session.
        
        With PAT, multiple addresses can be mapped to one or to a few addresses, because each private address is also tracked by a port number.
  - - - When packets are returned from outside the network, if the source port number was previously modified by the NAT-enable router, the destination port number will now be changed back to the original port number by the NAT-enabled router.
  - - - Static NAT is particularly useful for web servers or devices that must have a consistent address that is accessible from the internet, such as a company web server. It is also useful for devices that must be accessible by authorized personnel when offsite, but not by the general public on the internet.
        
        Static NAT requires that enough public addresses are available to satisfy the total number of simultaneous user sessions.
- - - - NAT-enabled routers can be configured with one or more valid public IPv4 addresses. These public addresses are known as the NAT pool
        
        When an internal device sends traffic out of the network, the NAT-enabled router translates the internal IPv4 address of the device to a public address from the NAT pool. To outside devices, all traffic entering and exiting the network appears to have a public IPv4 address from the provided pool of addresses.