Client Certificate Authentication or mTLS (Mutual TLS) with Azure App Service and Application Gateway

Why use mTLS is important?

mTLS, or mutual Transport Layer Security, is a protocol used for securing network communications by providing encryption, authentication, and integrity verification. It ensures that both the client and server are authenticated and verified before any data is exchanged, thus preventing man-in-the-middle attacks and other security threats. The use of mTLS is particularly important for applications that handle sensitive data, such as financial transactions or medical records, as it provides an additional layer of security beyond traditional TLS, which only authenticates the server. Additionally, mTLS can be used to enforce access control policies, ensuring that only authorized clients are able to connect to the server. Overall, the use of mTLS provides a strong and reliable method for securing network communications and protecting against a wide range of security threats.

What is the Azure Application Gateway?

Azure Application Gateway is a web traffic load balancer and application delivery controller service provided by Microsoft Azure. It enables customers to manage and optimize web traffic to their web applications.

The main features of Azure Application Gateway include SSL termination, routing, SSL offloading, multi-site routing, web application firewall, and autoscaling. It can be used to distribute traffic across multiple backend instances of web applications hosted on Azure Virtual Machines or other cloud services. It also provides advanced traffic management capabilities such as session affinity and URL-based routing.

Overall, Azure Application Gateway is a flexible and powerful service that can help customers improve the performance, security, and scalability of their web applications hosted on Azure or on-premises.

How to implement?

At the end of this post I added some important ref that you can implement and test the Client Certificate Authentication. Before start the below items need to setup:

  1. Azure App Service
  2. Azure Application Gateway
  3. Export a Trust Client CA Certificate

Reference Documents