What is Network Address Translation (NAT)? – NAT (Network Address Translation) – NAT is a feature that most people do not know but always use. The built-in NAT feature on ADSL modems converts Ip addresses when the computers on the network exit the internet.
What is Network Address Translation (NAT)?
What is Network Address Translation (NAT)?
What is Network Address Translation (NAT)? – You should have heard of the IPv4 protocol. Ip addresses on the Internet are observed to be consumed day by day. General IP addresses assigned by Internet Server Providers are dynamically and statically divided into two.
Dynamic IP addresses work with DHCP logic, and when you switch the ADSL modem off and on, the ADSL modem receives the dynamic IP address again. Static IP addresses, in communication with the Internet Service Provider, assign this general IP address to you for a certain fee.
These IP addresses used on the Internet are allocated from ICANN. Millions of people spend time on the internet every day. Do you think Ip addresses will suffice when we think that the number of people increases day by day and that these people are entering the internet?
Of course no! We use version 4 as the IP version. IPv4 addresses can be distributed to 4,294,967,296 IP addresses or can be allocated to corporate, enterprise and home users.
What Does NAT Do?
Let’s take a look at the title “What does NAT do?” after briefly explaining the title called “What is Network Address Translation (NAT)?”. The NAT feature is used to prevent the inadequacy of IPv4 IP addresses. CIDR technology is used for Service Providers or routing users while NAT is used for organizations or companies. CIDR technology definition is the (Classless Inter-Domain Router).
We use local IP addresses in the network environment. These IP addresses are private IP addresses and are used only in the local network.
These are Custom IP Addresses;
10.0.0.0 — 10.255.255.255
172.16.0.0 — 172.31.255.255
192.168.0.0 — 192.168.255.255
When using these private IP addresses on the local network, a computer with 192.168.1.100 IP address is automatically converted to a general IP address by NAT as it exits over the internet.
As an example from everyday life, in the ADSL modem we use in our home there is the NAT feature. When configuring the ADSL modem, we connect to the local network address. The local network part of the ADSL mode is called inside.
The computer that wants to exit internally from the inside comes in ADSL mode and from there NAT is converted to a general IP address to get to the outside. And so the computer on the LAN will be able to go to the internet environment. For example, if there were 50 computers on the LAN and you wanted to exit the network internally, we would need 50 IP addresses if there was no NAT. This scenario would be quite a hassle. But the NAT feature allows 50 computers to access the internet with 1 general IP address.
Active NAT Service over ADSL Modem;
What are NAT Advantages?
After the title called “What is Network Address Translation (NAT)?”, let’s explain “what are NAT advantages?”. NAT advantages are listed in 4 items below.
1 – With a few IP addresses, we can fetch many computer internets on the LAN.
2 – We can add new networks on the Local Area Network (LAN). We can change the existing network structure. After this we will only make a small change to the NAT settings.
3 – With NAT we can provide security on the internet. With NAT, computers provide great security by hiding local port numbers through port address translation when going out on the Internet.
4 – The only disadvantage of the NAT feature is that some implementations are experiencing difficulties. For example; FTP, IPSec …
What are NAT Types?
What are NAT types? NAT types can be separated by usage.
Basic NAT only performs address translation using a single generic IP address and does not use port mapping.
Unlike the Basic NAT feature, when we think about 5 Ip addresses purchased from Internet Service Provider, if one of the computers on the LAN wants to exit the Internet if one of these 5 Ip addresses is idle, it will Internet using that Ip address.
Port Address Translation (PAT)
NAT types are 3, Port Address Translation. NAT Port Address Translation is used to only internally connect all the computers on the LAN with a single public IP address.
NAT Port Address Loop uses local port numbers. These; The range is 1024 – 65535. Any of this range is assigned as the port number.
The only difference is that the port number is added when the IP address of the computer originating from the LAN goes through the conversion, and the port number is different if the internet is out.
PAT Port Address Translation Logic
NAT In PAT operation, when a computer on the LAN wants to connect to the HTTP server, the router looks at the router and router NAT table. If it does not find any record of this IP address, it will write the IP address + port number of the computer in the NAT table. The router then writes out the port number that the HTTP server uses on the outside when it is putting the computer on the Internet.
The opposite router receives the IP address. Since we do not know the IP address we used in our locale, it sends the packet to the IP address + Port number translated by our router. The packet coming from the opposite router is translated by our direction and reaches to the internal network.
The only difference between fixed NAT and Dynamic NAT operation is that any computer’s IP address in Fixed NAT is manually configured for the global Internet environment. In Dynamic NAT, the idle address of the purchased Ip addresses is used.
How NAT Works? ⇒ Video
You can watch how NAT works and you can also subscribe to our YouTube channel…
What is Network Address Translation (NAT)? – I have tried to give the information about “What is Network Address Translation (NAT)?”.
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