backend server certificate is not whitelisted with application gateway

AppGW is a PaaS instance , by default you wont get access to the Applicaiton Gateway. to your account. Thanks for contributing an answer to Stack Overflow! Message: Time taken by the backend to respond to application gateway's health probe is more than the timeout threshold in the probe setting. Application Gateway doesn't provide you any mechanism to create or purchase a TLS/SSL certificate. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. If your cert is issued by Internal Root CA , you would have export the root cert and import it the Trust Root Store in the Client. Internal server error. If Pick hostname from backend address is set in the HTTP settings, the backend address pool must contain a valid FQDN. Something that you will see missing is microsft docs is having a default site binding to a SSL certificate without the SNI enabled. Below is what happens during SSL negotiation when you have single chain cert and root in the AppGW. After the server starts responding (LogOut/ To learn how to create NSG rules, see the documentation page. If the domain is private or internal, try to resolve it from a VM in the same virtual network. My issue was due to the root certificate not being presented to appgw, and resulted in the error: "The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. Not the answer you're looking for? Otherwise please share the message in that scenario without adding root explicitly. To Answer we need to understand what happens in any SSL/TLS negotiation. How did you verify the cert? Ensure that you add the correct root certificate to whitelist the backend. If you can resolve the IP address, there might be something wrong with the DNS configuration in the virtual network. The text was updated successfully, but these errors were encountered: @EmreMARTiN, Thanks for the feedback. To resolve the issue, follow these steps. 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"). Do not edit this section. The authentication certificate is the public key of backend server certificates in Base-64 encoded X.509 (.CER) format. Connect and share knowledge within a single location that is structured and easy to search. In each case, if the backend server doesn't respond successfully, Application Gateway marks the server as Unhealthy and stops forwarding requests to the server. Failing endpoint is missing root CA as working one has it. #please-close. Check that the backend responds on the port used for the probe. I am having the same issue with App GW v1 in front of an API Management. Configure that certificate on your backend server. The output should show the full certificate chain of trust, importantly, the root certificate which is the one appgw requires. However when I replace all the 3 certificates to my CA cert, it goes red and warm me "Backend server certificate is not whitelisted with Application Gateway" The reason why I try to use CA . End-to-end SSL with Application Gateway v2 requires the backend server's certificate to be verified in order to deem the server Healthy. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. When calculating CR, what is the damage per turn for a monster with multiple attacks? For example: Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Thanks. Users can also create custom probes to mention the host name, the path to be probed, and the status codes to be accepted as Healthy. 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. Make sure https probe is configured correctly as well. If there's a custom DNS server configured on the virtual network, verify that the servers can resolve public domains. 10.0.0.4 = IP of backend server (if using DNS ensure it points to backend server and not the public IP of appgw). The status retrieved by any of these methods can be any one of the following states: If the backend health status for a server is healthy, it means that Application Gateway will forward the requests to that server. with your vendor and update the server settings with the new Were you able to reproduce this scenario and check? This article describes the symptoms, cause, and resolution for each of the errors shown. Application Gateway probes can't pass credentials for authentication. To verify, you can use OpenSSL commands from any client and connect to the backend server by using the configured settings in the Application Gateway probe. There is certificate with private key as PFX on listenner settings. If your cert is issued by Internal Root CA , you would have export the root cert and import it the Trust Root Store in the Client. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. Move to the Certification Path view to view the certification authority. If you do not have a support plan, please let me know. Create a free website or blog at WordPress.com. here is what happens in in Multiple chain certificate. Cause: End-to-end SSL with Application Gateway v2 requires the backend server's certificate to be verified in order to deem the server Healthy. For the server certificate to be trusted we need the Root certificate in Trusted Root Cert Store , usually if you are having certs issued by Godaddy,Digicert,Vergion like Third party Vendors you dont have to do anything because they are automatically trusted by your client/browser. b. @TravisCragg-MSFT: I have same configuration on different places which were built a while ago and those are perfectly working fine. Open a command prompt (Win+R -> cmd), enter netstat, and select Enter. -No client certificate CA names sent Sign in to the machine where your application is hosted. Select No, do not export the private key, and then click Next. In this example, you'll use a TLS/SSL certificate for the backend certificate and export its public key to be used as authentication certification. Now how can find if my application sending the complete chain , the easy way to find is running openssl from either windows client or Linux client which is present in the same network/subnet of the backend application. Cause: Application Gateway resolves the DNS entries for the backend pool at time of startup and doesn't update them dynamically while running. This post has been republished via RSS; it originally appeared at: New blog articles in Microsoft Tech Community. Can you please add reference to relevant Microsoft Docs page you are following? Select the root certificate and then select View Certificate. Solution: Depending on the backend server's response code, you can take the following steps. Ensure that you add the correct root certificate to whitelist the backend". Now how do we find if my application/backendserver is sending the complete chain to AppGW? Document Details To do end to end TLS, Application Gateway requires the backend instances to be allowed by uploading authentication/trusted root certificates. See Configure end to end TLS by using Application Gateway with PowerShell. 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. Now you have the authentication certificate/trusted root certificate in Base-64 encoded X.509(.CER) format. 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. Applicaiton works fine on the backend servers with 443 certificate from Digicert. Most of the browsers are thick clients , so it may work in the new browsers but reverse proxies like Application Gateway wont behave like our browsers they only trust the certificates if the backend sends the complete chain. But when we have multiple chain certificate and if your backend application/server sends only the leaf the certificate , AppGW will not be able to trust the cert up to the top level domain root. @EmreMARTiN , following up to see if the support case resolved your issue. This is the exact thing what we do when import .CER file in the HTTP Settings of the Application Gateway. The gateway listener is configured to accept HTTPS connections. The default route is advertised by an ExpressRoute/VPN connection to a virtual network over BGP. A few things to check: a. Access forbidden. I have the same issue, Root cert is DigiCert. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. This is the exact thing what we do when import .CER file in the HTTP Settings of the Application Gateway. This error can also occur if the backend server doesn't exchange the complete chain of the cert, including the Root > Intermediate (if applicable) > Leaf during the TLS handshake. Message: Body of the backend's HTTP response did not match the But if the backend health for all the servers in a backend pool is unhealthy or unknown, you might encounter problems when you try to access Thanks. Only HTTP status codes of 200 through 399 are considered healthy. Server will send its Certificate and because AppGW will already have its Root Cert, it verifies the backend server certificate and finds that it was issued by the Root cert which it is Trusting and they it starts connecting on HTTPs further for probing. Unfortunately I have to use the v1 for this set-up. For example, you can configure Application Gateway to accept "unauthorized" as a string to match. Visual Studio Code How to Change Theme ? To learn more, see our tips on writing great answers. f. Select Save and verify that you can view the backend as Healthy. If you can't connect on the port from your local machine as well, then: a. Sub-service: <---> Or, if Pick hostname from backend HTTP settings is selected in the custom probe, SNI will be set from the host name mentioned in the HTTP settings. The reason why I try to use CA cert is that I manage all the resource in terraform, with a single CA cert, it is better to automate the process. Check whether the virtual network is configured with a custom DNS server. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. Alternatively, you can do that through PowerShell/CLI. For testing purposes, you can create a self-signed certificate but you shouldn't use it for production workloads. In the v2 SKU, if there's a default probe (no custom probe has been configured and associated), SNI will be set from the host name mentioned in the HTTP settings. same situation as @JeromeVigne: App Gateway v1 as front-end to API Management, the health probe is unhealthy with the "Backend server certificate is not whitelisted with Application Gateway . The chain looks ok to me. To check the health of your backend pool, you can use the Sign in c. Check the user-defined routes (UDR) settings of Application Gateway and the backend server's subnet for any routing anomalies. If it's a self-signed certificate, you must generate a valid certificate and upload the root certificate to the Application Gateway HTTP settings. privacy statement. Ensure that you add the correct root certificate to whitelist the backend. Select the root certificate and click on View Certificate. How to organize your open apps in windows 11? You can add this to the application gateway to allow your backend servers for end to end TLS encryption. Make sure the UDR isn't directing the traffic away from the backend subnet. Check whether the server is listening on the port that's configured. Once the public key has been exported, open the file. multiple chain certificate and if your backend application/server sends only the leaf the certificate , AppGW . Ensure that you add the correct root certificate to allowlist the backend. If the certificate wasn't issued by a trusted CA (for example, if a self-signed certificate was used), users should upload the issuer's certificate to Application Gateway. Posted in Azure Tagged 502webserver, Azure, azure502, azureapplicationgateway, azurecertificate, azurewaf, backend certificate not whitelisted Post navigation Azure Cyber Security: Protect & Secure Your Cloud Infrastructure If you are using Azure Application Gateway as Layer 7 WAF for End to End SSL connectivity , you might have come across Certificate related issues most of the times. ", 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.". The default probe request is sent in the format of ://127.0.0.1:. However, we need few details. Please log in using one of these methods to post your comment: You are commenting using your WordPress.com account. For example, run the following command: Test-NetConnection -ComputerName www.bing.com -Port 443. Thank you everyone. The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. Already on GitHub? Thanks. By clicking Sign up for GitHub, you agree to our terms of service and b. For more information about how to extract and upload Trusted Root Certificates in Application Gateway, see Export trusted root certificate (for v2 SKU). To verify that Application Gateway is healthy and running, go to the Resource Health option in the portal, and verify that the state is Healthy. @TravisCragg-MSFT : Thank you! The text was updated successfully, but these errors were encountered: @sajithvasu I am not aware of any changes that have been made on the App Gateway side that would make this not work. Check whetheraccess to the path is allowed on the backend server. If you can resolve it, restart Application Gateway and check again. How to Restart Windows Explorer Process in Windows 11? This approach is useful in situations where the backend website needs authentication. Or, you can use Azure PowerShell, CLI, or REST API. OpenSSL> s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts Check the document page that's provided in step 3a to learn more about how to create NSG rules. @EmreMARTiN you can run openssl from your local machine pointing to your backend, not external over WAF. You should remove the exported trusted root you added in the App Gateway. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. Additionally, if you want to use a different text editor, understand that some editors can introduce unintended formatting in the background. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Most of the best practice documentation involves the V2 SKU and not the V1. A pfx certificate has also been added. https://docs.microsoft.com/en-us/azure/application-gateway/application-gateway-end-to-end-ssl-powershell, Azure Cyber Security: Protect & Secure Your Cloud Infrastructure, Send Text & WhatsApp Messages for Azure VM Status with Azure Automation, Migrate SOAR Use Cases from Splunk to Microsoft Sentinel, Azure Defender and Azure Sentinel Alerts Bi-Directional Sync. Also, please let me know your ticket number so that I can track it internally. I have some questions in regards to application gateway and need help with the same : 1)Is that application gateway can be configured with multiple backend pools and each pool can serve a request for different applications ? In the Certificate properties, select the Details tab. Which was the first Sci-Fi story to predict obnoxious "robo calls"? Now you may ask why it works when you browse the backend directly through browser. Sharing best practices for building any app with .NET. Export trusted root certificate (for v2 SKU): d. Check your OS firewall settings to make sure that incoming traffic to the port is allowed. For example: c. If it's not listening on the configured port, check your web server settings. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To find out the reason, check OpenSSL diagnostics for the message associated with error code {errorCode}. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Azure Application Gateway 502 Web Server Backend Certificate not whitelisted. thank you for sharing it . EDIT: Turned out I uploaded wrong pfx compared to the backend server. Find centralized, trusted content and collaborate around the technologies you use most. You must have a custom probe to change the timeout value. If the certificate wasn't issued by a trusted CA (for example, if a self-signed certificate was used), users should upload the issuer's certificate to Application Gateway. For more information about how to extract and upload Trusted Root Certificates in Application Gateway, see Export trusted root certificate (for v2 SKU). Azure Tip #5 Change Color Theme in Azure Portal, Azure Tip #1 Azure Services offered by Microsoft, Azure Tip #8 Fix Data for certificate is Invalid error, Azure Tip #6 Reset the Microsoft Azure Dashboard. Trusted root certificate mismatch Azure Applicaiton Gateway V2 Certification Issue, https://docs.microsoft.com/en-us/azure/application-gateway/certificates-for-backend-authentication#export-trusted-root-certificate-for-v2-sku, https://docs.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku, Enabling end to end TLS on Azure Application Gateway, articles/application-gateway/ssl-overview.md, https://docs.microsoft.com/en-us/azure/cloud-shell/overview. AppGW is a PaaS instance , by default you wont get access to the Applicaiton Gateway. For example, you can use OpenSSL to verify the certificate and its properties and then try reuploading the certificate to the Application Gateway HTTP settings. 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. Cause: After Application Gateway sends an HTTP(S) probe request to the I am using the base64 encoded .CER file without the chain (w/o intermediary and root) at the https setting of the backend settings of application gateway and it is working fine (see image below). You'll see the Certificate Export Wizard. Access the backend server directly and check the time taken for the server to respond on that page. i have configured a Azure Application gateway (v2) and there is one backend servers. You can choose to use any other tool that is convenient. Just FYI. Traffic should still be routing through the Application Gateway without issue. In 5e D&D and Grim Hollow, how does the Specter transformation affect a human PC in regards to the 'undead' characteristics and spells? In Azure docs, it is clearly documented that you dont have to import Auth certificate in HTTP settings of the backend if your backend application has Global trusted certificate. On the Details tab, select the Copy to File option and save the file in the Base-64 encoded X.509 (.CER) format. Save the custom probe settings and check whether the backend health shows as Healthy now. An issue with your configuration needs to be ruled out first. Microsoft Alias: <--->. If they aren't, create a new rule to allow the connections. Azure Tip #10 Load Balancer vs Traffic Manager, Azure Tip #2 Azure Free Subscription without CreditCard for Learning Sandbox, Azure Charts All about Azure news, stats, and Changes, 100 Multiple Choice Questions & Answers on Microsoft Outlook, 100 Multiple Choice Questions & Answers on PowerPoint. Service: application-gateway; GitHub Login: @vhorne; Microsoft Alias: absha; The text was updated successfully, but these errors were encountered: . Nice article mate! document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Design a site like this with WordPress.com, Troubleshoot backend health issues in Azure Application Gateway | Microsoft Docs. Backend Nginx works just fine with https, but the application gateway https health probes fail with the message "Backend server certificate is not whitelisted with Application Gateway." What is the deal here? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. For File name, name the certificate file. 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/ Configure that certificate on your backend server. If you don't mind can you please post the summary of the root here to help people who might face similar issue. The issue was on certificate. On the App Gateway side, there are 6 public listeners are on the App Gateway with public .pfx certs, and 6 authentication certificates (.cer) within the HTTPsSettings, a single backendpool with both VMs configured, and various rules created. Quickstart - Configure end-to-end SSL encryption with Azure Application Gateway - Azure portal, articles/application-gateway/end-to-end-ssl-portal.md, https://www.domstamand.com/end-to-end-ssl-solution-using-web-apps-and-azure-application-gateway-multisite-hosting/, https://learn.microsoft.com/en-us/azure/application-gateway/ssl-overview#for-probe-traffic, Version Independent ID: 948878b1-6224-e4c5-e65a-3009c4feda74. If you are using Azure Application Gateway as Layer 7 WAF for End to End SSL connectivity , you might have come across Certificate related issues most of the times. Current date is not within the "Valid from" and "Valid to" date range on the certificate. @einarasm read thru the responses from @krish-gh, specifically around leveraging OpenSSL toolkit to query the backend pool for the certificate trust chain, example: %> openssl s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. If you receive this error message, the CN of the backend certificate doesn't match the host name configured in the custom probe, or the HTTP settings if Pick hostname from backend HTTP settings is selected. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. Solution: To resolve this issue, verify that the certificate on your server was created properly. Have done s_client -connect backend_ip:443 -servername backend_url -showcerts and found that Root CA is missing. I will clean-up some of my older comments to keep it generic to all since the issue has been identified. Which language's style guidelines should be used when writing code that is supposed to be called from another language? You can use any tool to access the backend server, including a browser using developer tools. Select the root certificate and then select, In the Certificate properties, select the, Verify the CN of the certificate from the details and enter the same in the host name field of the custom probe or in the HTTP settings (if. We have private key .pfx issued by CA uploaded to app services and its public certificate .cer file uploaded to app gateway backend authentication as mentioned in this document. In this example, you'll use a TLS/SSL certificate for the backend certificate and export its public key to be used as . But if this message is displayed, it suggests that Application Gateway couldn't successfully resolve the IP address of the FQDN entered. I will post any updates here as soon as I have them. Learn more about Application Gateway diagnostics and logging.

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backend server certificate is not whitelisted with application gateway