Difference between NAT and NAPT
NAPT is a network translation technology that can translate port numbers in addition to NAT technology. As a result, NAPT has enabled multiple simultaneous connections, which was an issue with NAT.
Therefore, NAPT can be said to be a powered-up version of NAT.
What is NAT?
Overview of NAT
So what exactly is NAT?
NAT is one of the network address translation technologies and refers to a technology that converts a private IP address into a global IP address.
Private IP address and global IP address
global IP address
So what are private IP addresses and global IP addresses?
An IP address is like an address in the network world.
This IP address is managed by an organization called ICANN (abbreviation of The Internet Corporation for Assigned Names and Numbers) called ICAN.
One of ICANN’s jobs is to ensure that IP addresses do not overlap in the network world.
Since the IP address is the address of the network world, if it overlaps, it will cause confusion in the network world.
A unique IP address that ICANN does not allow duplication is called a global IP address.
private IP address
There is concern that the global IP addresses that appeared earlier will eventually run out in the network world. IP addresses exist in a world of 32 bits, or 32 0’s and 1’s, and there are just under 4.3 billion global IP addresses, but even such a number is expected to be in short supply in the world of ever-expanding networks. It has been.
Therefore, even if one company has 30 PCs that they want to connect to the network, ICANN will not assign a global IP address to each of them. However, ICANN also provides IP addresses that can be freely used by organizations that own global IP addresses.
This is your private IP address.
This private IP address is used when one organization wants to connect to the network from multiple devices, as in the example of the company earlier.
Why do we need NAT?
Then again, why is NAT technology necessary?
Going back to the topic of global and private IP addresses earlier, if the global IP address is the address in the world of the network, then the private IP address is like the name of the room within that address. For example, a private IP address corresponds to “Children’s room” or “Room 201”.
In the network world, it is necessary to clarify the global IP address to connect to the network for communication and the global IP address to connect to, but if you do not do anything, people using private IP addresses You will not be able to connect to the network.
Therefore, we use NAT technology to convert private IP addresses to global IP addresses so that even devices using private IP addresses can be connected to the network.
As an image, there is a world where a letter cannot be sent unless the address of the destination and the sender are specified, and a person who usually spends his time in the “children’s room” writes a letter from the “children’s room”. It’s like writing the address of the house firmly without writing it.
Challenges of NAT
NAT is a convenient function that converts private IP addresses to global IP addresses and prevents the exhaustion of global IP addresses, but it also has weaknesses.
It is that more users than the number of global IP addresses cannot connect to the network at the same time.
In other words, an organization that owns one global IP address and manages private IP addresses within it cannot connect to the network when someone else is connected to the network. NAPT
solves these problems.
What is NAPT?
Overview of NAPT
As I mentioned earlier, although NAT is a convenient feature, it had the problem that multiple people could not connect to the network at the same time.
It was NAPT that solved this, but how did you deal with it?
Not only did it convert from a private IP address to a global IP address, NAPT tried to respond by changing the port number as well.
Change port number
So why did changing the port number solve the NAT problem of not being able to connect multiple devices at the same time?
Port literally means “harbor”.
The NAT problem was caused by this port number not changing, but as an image, there was only one port, so it was difficult for ships to come and go, in other words, network communication.
NAPT changed this port number and created multiple ports to allow simultaneous connections.
