How To Connect Azure App Service to S2S VPN: Troubleshooting Guide

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If you’re trying to connect an App Service to a Virtual Private Network (VPN) using a Site-to-Site (S2S) connection, you might run into some common issues that prevent it from working smoothly. Fortunately, setting this up is possible, but it requires a few specific steps to ensure everything is configured correctly.

First, it’s important to understand that App Services are hosted in a shared environment within Azure, which can make direct VPN connectivity more challenging. To establish a secure connection from your App Service to your internal network via S2S VPN, you’ll need to use a workaround — typically, setting up a network integration instead.

Here’s a simple way to do this:

Create a Virtual Network (VNet):
Start by creating a Virtual Network inside your Azure portal if you haven’t already. This will serve as a secure bridge between your App Service and your on-premises network.
Set Up the VPN Gateway:
Next, you need to establish a VPN Gateway connected to your local network. This acts as the secure tunnel for your data, allowing your Azure VNet to communicate privately with your internal network.
Configure the Virtual Network Integration for Your App Service:
Navigate to your App Service in the Azure portal and find the “Networking” section. Use “VNet Integration” to connect your app to the Azure VNet you created. This doesn’t set up a direct VPN connection from the app itself but allows it to securely communicate with resources within that network.
Connect the VNet to Your On-Premises Network:
Ensure your VPN Gateway is correctly linked to your local network via the S2S VPN, so resources inside your network are accessible from the App Service through the VNet.
Test Your Connection:
Once everything is configured, do some testing. Try accessing your internal resources from your app, and verify that the connection is secure and stable.

Keep in mind, direct app-to-VPN connection isn’t directly supported—this method leverages internal network integration to work around that limitation. If you follow these steps carefully, your App Service should be able to communicate securely with your on-premises network through your S2S VPN connection.