Difference Between Internet Gateway and NAT Gateway

Pre-requisite: AWS

In the world of networking, the terms “Internet Gateway” and “NAT Gateway” are commonly used, but they can often be confusing. In this article, we will explain the difference between an Internet Gateway and NAT Gateway. We will define each term and explain how they work, their use cases, and the main differences between them.

An Internet Gateway allows resources within a VPC to communicate with the internet. It is a horizontally scaled, redundant, and highly available VPC component that enables bidirectional communication between instances in a VPC and the internet. An Internet Gateway is also known as a virtual router because it routes traffic between your VPC and the internet. An Internet Gateway works by establishing a connection between a VPC and the internet. The VPC must have a public subnet, and the instances within that subnet must have a public IP address to communicate with the internet. An Internet Gateway acts as a bridge between the VPC and the internet, and it is responsible for translating private IP addresses within the VPC to public IP addresses. An Internet Gateway is commonly used when you want resources within a VPC to be accessible from the internet. For example, if you have a web server running within your VPC, you can use an Internet Gateway to make it accessible from the internet.

Step 1: Open the Amazon VPC console.
 

Step 2: In the navigation pane, choose “Internet Gateways”.
 

Step 3: Choose “Create Internet Gateway”.
 

Step 4: Enter a name for your Internet Gateway and choose “Create”.
 

A NAT Gateway enables instances in a private subnet to connect to the internet or other AWS services but prevents the internet or other AWS services from initiating a connection with those instances. A NAT Gateway works by translating the private IP addresses of instances within a private subnet to public IP addresses. When an instance in a private subnet wants to communicate with the internet, it sends the traffic to the NAT Gateway. The NAT Gateway then translates the private IP address to a public IP address and sends the traffic to the internet.
A NAT Gateway is commonly used when you have resources within a private subnet that require outbound internet access but should not be directly accessible from the internet. For example, if you have a database server running within your VPC, you can use a NAT Gateway to allow it to access the internet for software updates or to retrieve data from an external source.

Step 1: Open the Amazon VPC console.
 

Step 2: In the navigation pane, choose “NAT Gateways”.
 

Step 3: Choose “Create NAT Gateway”.
 

Step 4: Select the subnet where you want to create the NAT Gateway.
 

Step 5: Choose an existing Elastic IP address or create a new one.
 

Step 6: Choose “Create NAT Gateway”.