Network Address Translation | Different types of NAT

In this article, we will discuss NAT (Network Address Translation). Before continuing, I recommend you to read my Public and Private IP address article. NAT is also known as IP masquerading. Let’s continue!

what-is-nat

Why we need NAT?

NAT, is often used to translate private IP addresses to public IP addresses. As we already know, our private IP addresses are valid only on our LAN (Local Area Network). So, in this situation, we need a lot of Public IP address in order to provide Internet connectivity to all users. But, here NAT plays a vital role. NAT can provide Internet connectivity to many LAN users over a single public IP address. This technique helps a lot to save IPv4 address space.

There are many varieties of NAT available. We just have to configure it according to our need. A part of saving IPv4 space, it also masquerade IP addresses. We can simply hide our private IP address from public internet or from  “Hacker World”. Although, it also helps to create a secure DMZ (Demilitarized zone).

Different types of NAT

There are three types of NAT available. Static NAT, Dynamic NAT and Port Address Translation (PAT). Each type of NAT has different characteristics. Below we will discuss each type in more details.

Static NAT

Static NAT, is the basic type of NAT. Here, one private IP address converts into one public IP. So, it can hide only a single private IP address.

what-is-static-nat

Dynamic NAT

Basically dynamic NAT is the same as Static NAT, but here we have a pool of public IP addresses. Thus, it automatically takes a free IP from public IP pool and automatically modified IP header of the packet.

The Dynamic NAT is used in large enterprise network. Bigger companies purchase a huge amount of Public IP addresses and keep them in a pool. This pool is assigned to a group of hosts, and it starts providing public IP addresses to these hosts.

what-is-dynamic-nat

PAT (Port Address Translation)

PAT stands for Port Address Translation. It is the most famous NAT type. It is used to provide Internet connectivity to a large number of Hosts by using a single Public IP address. PAT is widely used in Home, Campus and Enterprises Network.

PAT, usually configured on most of the network. Here, Internet Service Provider (ISP) provides a static Public IP on a router or firewall. Each time, when an internal Hosts want to initiate a connection to the public Server, then Router, will assign a port number and translate their private IP address to a public IP. Although, at the same time, other internal Host’s can initiate the connection with Public Server’s.

what-is-port-address-translation

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Summary

In this article, we discussed about NAT (Network Address Translation). NAT is basically masquerading our private IP addresses from public domain. NAT has three types, although, PAT (Port Address Translation), is one of the famous type which can provide Internet connectivity to thousands of users with the help of single IP address.

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