Introduction to IP Whitelisting

IP whitelisting is a security practice where you allow access to your API only from specific IP addresses. When you use IP whitelisting, the API gateway checks every incoming request and only accepts connections from trusted sources. Any request from an IP address not on the approved list is blocked automatically.

You use IP whitelisting to protect your API from unauthorized access. This approach is especially useful when you want to limit API usage to known partners, internal systems, or specific clients. By controlling which IP addresses can reach your API, you reduce the risk of attacks and prevent unwanted traffic from reaching your backend services.

How API Gateways Use IP Whitelisting

API Gateways often act as the main entry point for all requests coming into your system. You can use IP whitelisting to make sure that only requests from trusted sources are allowed to access your services.

With IP whitelisting, you create a list of IP addresses that are allowed to reach your APIs. Any request coming from an IP address not on the list is automatically blocked by the gateway.

Simple Example

Suppose you have an API that should only be accessed by your company’s office network. Your office uses the IP address 203.0.113.42. You add this address to your IP whitelist in the API Gateway configuration.

• If a request comes from 203.0.113.42, the gateway allows it through to your services;
• If a request comes from any other address, such as 198.51.100.17, the gateway blocks it and returns an error message.

This approach helps you:

• Prevent unauthorized access from unknown networks;
• Limit exposure of your APIs to the public internet;
• Quickly update the whitelist if you need to grant or remove access for certain locations.

IP whitelisting is a simple but effective way to protect your APIs from unwanted traffic.