The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. For example, check whether the database has any issues that might trigger a delay in response. Once the public key has been exported, open the file. i.e. By clicking Sign up for GitHub, you agree to our terms of service and Message: Application Gateway could not connect to the backend. Access the backend server directly and check the time taken for the server to respond on that page. From the properties displayed, find the CN of the certificate and enter the same in the host name field of the http settings. The v2 SKU is not an option at the moment due to lack of UDR support. Cause: When you create a custom probe, you can mark a backend server as Healthy by matching a string from the response body. The error says that Root cert is not whitelisted on the AppGW , but you might have a valid Third party certificate on the backend , and more over if you try to access the backend directly bypassing the Application Gateway you will not see any issues related to certificate in the browser. The intermediate certificate(s) should be bundled with server certificate and installed on the backend server. Already on GitHub? New blog articles in Microsoft Tech Community, Troubleshoot backend health issues in Azure Application Gateway | Microsoft Docs, Set up Granular Delegated Admin Privileges in Microsoft 365 Lighthouse, Data Mapper Patterns: Conditional Mapping, Windows Server Summit 2022: Modernize your Apps with Windows Containers and AKS, Kubernetes External DNS for Azure DNS & AKS, Update: Addressing Karis Law and Ray Baums Act with Microsoft Teams phone system, SSIS Always on AG (Availability Group) and Error Please Create a Master Key, Azure Marketplace new offers January 4, 2023. Thanks. To create a custom probe, follow these steps. Have a question about this project? Just FYI. I guess you need a Default SITE binding to a certificate, without SNI ticked. Solution: If you receive this error message, there's a mismatch between the certificate that has been uploaded to Application Gateway and the one that was uploaded to the backend server. -Verify return code: 19 (self signed certificate in certificate chain). Here is a blog post to fix the issue. Export trusted root certificate (for v2 SKU): Now use steps 2-9 mentioned in the section Export authentication certificate from a backend certificate (for v1 SKU) above to export the trusted root certificate in the Base-64 encoded X.509(.CER) format. Either allow "HTTP 401" in a probe status code match or probe to a path where the serverdoesn't require authentication. Verify that the response body in the Application Gateway custom probe configuration matches what's configured. On the Subnets tab of your virtual network, select the subnet where Application Gateway has been deployed. And each pool has 2 servers . You should do this only if the backend has cert which is issued by internal CA, I hope we are clear till now on why we import Authenticate cert in the HTTP settings of the AppGW and when we use the option "Use Well Known CA", But the actual problem arises if you are using a Third party Cert or Internal CA Cert which has Intermediate CA and then Leaf certificate, Most of the orgs for security reasons use Root Cert----> Intermediate Cert ------> Leaf Cert , even Microsoft follows the same for bing , check the screenshot below, Now lets discuss what exactly is the confusion here if we have multiple Chain Cert, When you have single chain certificate , then there will be no confusion with appgw , if your root CA is Global trusted just select "Use Trusted Root CA" option in HTTPsettings, If you root CA is Internal CA , then import that Top root cert in .cer format and upload it in the HTTP settings. To resolve the issue, follow these steps. For all TLS related error messages, to learn more about SNI behavior and differences between the v1 and v2 SKU, check the TLS overview page. https://docs.microsoft.com/en-us/azure/application-gateway/certificates-for-backend-authentication#export-trusted-root-certificate-for-v2-sku, End-to-end TLS with the v2 SKU of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. Make sure the UDR isn't directing the traffic away from the backend subnet. Set the destination port as anything, and verify the connectivity. If the server returns any other status code, it will be marked as Unhealthy with this message. Select the root certificate and click on View Certificate. The custom DNS server is configured on a virtual network that can't resolve public domain names. The current data must be within the valid from and valid to range. f. Select Save and verify that you can view the backend as Healthy. Ensure that you add the correct root certificate to whitelist the backend". Our configuration is similar to this article but we are using WAF V1 sku - https://www.domstamand.com/end-to-end-ssl-solution-using-web-apps-and-azure-application-gateway-multisite-hosting/ Sure I would be glad to get involved if needed. b. I will wait for your response. I have two listeners and my issue has started on one of them when SSL certificate has been renewed. rev2023.5.1.43405. Configure that certificate on your backend server. Learn how your comment data is processed. If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? I had to add a directive in the webserver conf file to enable presentation of the full trust chain. If you've already registered, sign in. ", The UDR on the Application Gateway subnet is set to the default route (0.0.0.0/0) and the next hop is not specified as "Internet.". Currently we are seeing issues with app gateway backend going unhealthy due to backend auth cert. Backend Health page on the Azure portal. https://learn.microsoft.com/en-us/azure/application-gateway/certificates-for-backend-authentication#export-trusted-root-certificate-for-v2-sku, End-to-end TLS with the v2 SKU Internal server error. Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action in Windows 11. You can add this github issue reference in your ticket so that the Azure support personnel can see the details without asking you to repeat these steps. Every documentation page has a feedback section at the bottom. Error message shown - Backend server certificate is not whitelisted with Application Gateway. Because the probe requests don't carry any user credentials, they will fail, and an HTTP 401 status code will be returned by the backend server. To Answer we need to understand what happens in any SSL/TLS negotiation. Check whetheraccess to the path is allowed on the backend server. It worked fine for me with the new setup in the month of September with V1 SKU. Our backend web server is running Apache with multiple HTTPS sites on the same server and the issue we face is regardless of the HTTPS . If you have properly added the certificate, and the backend pool is pointing to the custom domain (not the azurewebsites.net domain), then your best options are to either try the V2 SKU, or open a support request to troubleshoot further. We have this setup in multiple places created last year and it all works fine. Export trusted root certificate (for v2 SKU): Content Source:<---> Change), You are commenting using your Facebook account. https://learn.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. This will take some time to track down, fix, and the docs will need to be updated with limitations & best practices. How did you verify the cert? Cause: After the DNS resolution phase, Application Gateway tries to connect to the backend server on the TCP port that's configured in the HTTP settings. Solution: To resolve this issue, follow these steps: Learn more about Application Gateway probe matching. If you see an Unhealthy or Degraded state, contact support. The issue was on certificate. Azure Tip #3 What is Scale up and Scale Out ? here is what happens in in Multiple chain certificate. Trusted root certificate is required to allow backend instances in application gateway v2 SKU. Message: Backend certificate is invalid. If you have an ExpressRoute/VPN connection to the virtual network over BGP, and if you're advertising a default route, you must make sure that the packet is routed back to the internet destination without modifying it. Check whether your server allows this method. If the certificate wasn't issued by a trusted CA (for example, a self-signed certificate was used), users should upload the issuer's certificate to Application Gateway. Now how do we find if my application/backendserver is sending the complete chain to AppGW? Most of the browsers are thick clients , so it may work in the new browsers but PRODUCTs like Application Gateway will not be able to trust the cert unless the backend sends the complete chain. when the backend server cert hits AppGW after Server Hello , AppGW tries to check who issued the certificate and it finds that it was issued by Intermediate certificate but then it does not have information about Intermediate cert, like who issued the cert and what is the root certificate of that intermediate certificate. e. In the Inbound Rules section, add an inbound rule to allow destination port range 65503-65534 for v1 SKU or 65200-65535 v2 SKU with the Source set as GatewayManager service tag. Configure that certificate on your backend server. Content: <---> If they don't match, change the probe configuration so that it has the correct string value to accept. To troubleshoot this issue, check the Details column on the Backend Health tab. This article describes the symptoms, cause, and resolution for each of the errors shown. To learn more, see our tips on writing great answers. c. Check to see if there are any default routes (0.0.0.0/0) with the next hop not set as Internet. If the backend health status is Unhealthy, the portal view will resemble the following screenshot: Or if you're using an Azure PowerShell, CLI, or Azure REST API query, you'll get a response that resembles the following example: After you receive an unhealthy backend server status for all the servers in a backend pool, requests aren't forwarded to the servers, and Application Gateway returns a "502 Bad Gateway" error to the requesting client. You must be a registered user to add a comment. Message: Status code of the backend's HTTP response did not match the probe setting. Thanks. Ive recently faced with the dreaded 502 Web Server error when dealing with the App Gateway, my Backend Health was screaming unhealthy Backend server certificate is not whitelisted with Application Gateway. If Application Gateway can't establish a TCP session on the port specified, the probe is marked as Unhealthy with this message. Message: The Common Name (CN) of the backend certificate doesn't match the host header of the probe. Expected:{HTTPStatusCode0} Received:{HTTPStatusCode1}. Find out more about the Microsoft MVP Award Program. Check to see if a UDR is configured. The application gateway then tries to connect to the server on the TCP port mentioned in the HTTP settings. The following steps help you export the .cer file in Base-64 encoded X.509(.CER) format for your certificate: If you can't find the certificate under Current User\Personal\Certificates, you may have accidentally opened "Certificates - Local Computer", rather than "Certificates - Current User"). If the output doesn't show the complete chain of the certificate being returned, export the certificate again with the complete chain, including the root certificate. Below is what happens during SSL negotiation when you have single chain cert and root in the AppGW. To restart Application Gateway, you need to. Traffic should still be routing through the Application Gateway without issue. Required fields are marked *. Choose the destination manually as any internet-routable IP address like 1.1.1.1. I have created an application gateway with 3 backend nodes, when I set the "Http Listener" with all the 3 nodes certificates, the health probe is green.