Thanks for contributing an answer to Stack Overflow! Let me know here if you face any issue reaching Azure support or if you do not have any support plan for your subscription. i had this issue for client and split multiple vms ! OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. It is required for docs.microsoft.com GitHub issue linking. Azure Application Gateway health probe error with "Backend server I did not find this error message listed here https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting. This is the exact thing what we do when import .CER file in the HTTP Settings of the Application Gateway. If your backend is within a VNET not accessible from your local, the you run openssl from a Cloud Shell within VNET. The certificate added to Backend HTTP Setting to authenticate the backend servers can be the same as the certificate added to the listener for TLS termination at application gateway or different for enhanced security. @TravisCragg-MSFT: Thanks for checking this. 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. 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. I have the same issue, Root cert is DigiCert. Or, you can use Azure PowerShell, CLI, or REST API. 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. Ensure that you add the correct root certificate to whitelist the backend. Passing negative parameters to a wolframscript. It is required for docs.microsoft.com GitHub issue linking. To learn how to create NSG rules, see the documentation page. Configure that certificate on your backend server. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? here is the sample command you need to run, from the linux box that can connect to the backend application. I am opening a PR to update the End-to-End Howto guide with a description of the error and a link to the SSL overview. Message: The server certificate used by the backend is not signed by a well-known Certificate Authority (CA). error. One pool has 2 servers listed as unhealthy and the error message we see is below: "backend server certificate is not whitelisted with application gateway .Make sure that the certificate uploaded to the application gateway matches with the certificate configured in the backend servers. 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. 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. Check whether your UDR has a default route (0.0.0.0/0) with the next hop not set as Internet: a. privacy statement. In this example, you'll use a TLS/SSL certificate for the backend certificate and export its public key to be used as . Backend Health page on the Azure portal. Message: The root certificate of the server certificate used by the backend doesn't match the trusted root certificate added to the application gateway. -> Same certificate with private key from applicaton server. How do I bypass Microsoft account login in Windows11? If you don't mind can you please post the summary of the root here to help people who might face similar issue. But when we have multiple chain certificate and your backend application is sending the Application Gateway only the leaf the certificate , AppGW will not be able to trust the cert up to the top level domain root. I just set it up and cannot get the health probe for HTTPS healthy. Walkthrough: Configuring end-to-end TLS with Application Gateway and Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Azure Application Gateway Probe Configuration, Azure App Gateway gives Error 404 but backend probe is healthy, Azure Application Gateway Health Probe Error, Azure Application Gateway : Backend server certificate expired. probe setting. During SSL negotiation , Client sends "Client Hello" and Server Responds with "Server Hello" with its Certificate to the Client. of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. How to Restart Windows Explorer Process in Windows 11? 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 . A few of the common status codes are listed here: Or, if you think the response is legitimate and you want Application Gateway to accept other status codes as Healthy, you can create a custom probe. Azure Nwtworking> Azure Application Gateway: 502 error due to backend certificate not whitelisted in the AppGW, https://techcommunity.microsoft.com/t5/azure-networking-blog/azure-application-gateway-502-error-due-to-backend-certificate/ba-p/3271805, 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. This approach is useful in situations where the backend website needs authentication. If you see an Unhealthy or Degraded state, contact support. 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. Were you able to reproduce this scenario and check? Check whether your server allows this method. 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 ? An existing backend certificate is required to generate the authentication certificates or trusted root certificates required for allowing backend instances with Application Gateway. If probes are routed through a virtual appliance and modified, the backend resource will display a 200 status code and the Application Gateway health status can display as Unknown. What was the resolution? Document Details d. If an NSG is configured, search for that NSG resource on the Search tab or under All resources. Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action in Windows 11. This configuration further secures end-to-end communication. If the backend server response for the probe request contains the string unauthorized, it will be marked as Healthy. https://docs.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. You can use any tool to access the backend server, including a browser using developer tools. It worked fine for me with the new setup in the month of September with V1 SKU. Ive deployed 2 Virtual Machines in North Europe (Across Zones 1 and 2) both configured with IIS with 6 sites with different URLs (all with Server Name Indication ticked) installed all the certificates to match their names as-well. Your email address will not be published. https://learn.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. From your TLS/SSL certificate, export the public key .cer file (not the private key). @TravisCragg-MSFT : Thank you! Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. If the setting is either Virtual Appliance or Virtual Network Gateway, you must make sure that your virtual appliance, or the on-premises device, can properly route the packet back to the Internet destination without modifying the packet. Access forbidden. Solution: If your TLS/SSL certificate has expired, renew the certificate The output should show the full certificate chain of trust, importantly, the root certificate which is the one appgw requires. Learn more about Application Gateway diagnostics and logging. If Internet and private traffic are going through an Azure Firewall hosted in a secured Virtual hub (using Azure Virtual WAN Hub): a. -Verify return code: 19 (self signed certificate in certificate chain). For example: c. If it's not listening on the configured port, check your web server settings. 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. "backend server certificate is not whitelisted with application gateway .Make sure that the certificate uploaded to the application gateway matches with the certificate configured in the backend servers. Make sure the UDR isn't directing the traffic away from the backend subnet. 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 Reference document: https://learn.microsoft.com/en-us/azure/application-gateway/ssl-overview#for-probe-traffic. Azure Application Gateway: 502 error due to backend certificate not By clicking Sign up for GitHub, you agree to our terms of service and Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. To find out the reason, check OpenSSL diagnostics for the message associated with error code {errorCode}. Backend protocol: HTTPS Backend port: 443 Use well known CA certificate: Yes Cookie-based affinity*: Disable Connection draining*: Disable Request time-out*: 20 seconds Override backend path*: Blank Override with new host name: Yes Host name override: Override with a specific domain name (webappX.hugelab.net) Use custom probe: Yes (Ep. End-to-end SSL with Application Gateway v2 requires the backend server's certificate to be verified in order to deem the server Healthy. Save the custom probe settings and check whether the backend health shows as Healthy now. For a TLS/SSL certificate to be trusted, that certificate of the backend server must be issued by a CA that's included in the trusted store of Application Gateway. Do not edit this section. I can confirm that it's NOT a general issue or bug of the product. 2)How should we get this issue fixed ? If the backend server doesn't c. Check to see if there are any default routes (0.0.0.0/0) with the next hop not set as Internet. To create a custom probe, follow these steps. Received response body doesn't contain {string}. 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. If the server returns any other status code, it will be marked as Unhealthy with this message. In this article I am going to talk about one most common issue "backend certificate not whitelisted", If you check the backend health of the application gateway you will see the error like this "The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. 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. Required fields are marked *. For example, check for routes to network virtual appliances or default routes being advertised to the Application Gateway subnet via Azure ExpressRoute and/or VPN. I am 3 backend pools . 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. 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. You can find this by running openssl from either windows client or Linux client which is present in the same network/subnet of the backend application. Which was the first Sci-Fi story to predict obnoxious "robo calls"? 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. This is the exact thing what we do when import .CER file in the HTTP Settings of the Application Gateway. If the output doesnt show the complete chain of the certificate being returned, export the certificate again with the complete chain, including the root certificate. If you can't connect on the port from your local machine as well, then: a. 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. 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. b. Azure Tip #11 Get Reports of ARM Deployments in Your Subscription. respond within the configured period (the timeout value), it's marked as Unhealthy until it starts responding within the configured timeout period again. Select No, do not export the private key, and then click Next. 10.0.0.4 = IP of backend server (if using DNS ensure it points to backend server and not the public IP of appgw). Then, click Next. -No client certificate CA names sent The gateway listener is configured to accept HTTPS connections. For more information about how to extract and upload Trusted Root Certificates in Application Gateway, see Export trusted root certificate (for v2 SKU). When we check the certificate with the openssl there were following errors: 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. Failed health probe in Azure Application Gateway : r/AZURE - Reddit If the port mentioned is not the desired port, enter the correct port number for Application Gateway to connect to the backend server. Azure Application Gateway: 502 error due to backend certificate not As described earlier, the default probe will be to ://127.0.0.1:/, and it considers response status codes in the range 200 through 399 as Healthy. Ensure that you add the correct root certificate to allowlist the backend. 7 19 comments Add a Comment Nillsf 4 yr. ago Next hop: Internet. Thanks! Troubleshoot backend health issues in Application Gateway What are the advantages of running a power tool on 240 V vs 120 V? For a TLS/SSL certificate to be trusted, the backend server certificate must be issued by a CA that's included in the trusted store of Application Gateway. Well occasionally send you account related emails. On the Export File Format page, select Base-64 encoded X.509 (.CER)., and then click Next. Making statements based on opinion; back them up with references or personal experience. An Azure service that provides a platform-managed, scalable, and highly available application delivery controller as a service. 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. to your account. Fast-forward 2022, we are also faced with the same issue and getting the same error "Backend server certificate is not whitelisted with Application Gateway" using Application Gateway v1. To Answer we need to understand what happens in any SSL/TLS negotiation. You signed in with another tab or window. You must have a custom probe to change the timeout value. If they don't match, change the probe configuration so that it has the correct string value to accept. Traffic should still be routing through the Application Gateway without issue. After CA autohority re-created the certificate problem was gone. In this article I am going to talk about one most common issue "backend certificate not whitelisted" This operation can be completed via Azure PowerShell or Azure CLI. Is there a generic term for these trajectories? For example, you can configure Application Gateway to accept "unauthorized" as a string to match. certificate. Verify that the FQDN entered in the backend pool is correct and that it's a public domain, then try to resolve it from your local machine. You should remove the exported trusted root you added in the App Gateway. This happens when an NSG/UDR/Firewall on the application gateway subnet is blocking traffic on ports 65503-65534 in case of v1 SKU, and ports 65200-65535 in case of the v2 SKU or if the FQDN configured in the backend pool could not be resolved to an IP address. Azure Application Gateway: 502 error due to backend certificate not When i check health probe details are following: Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. here is the sample command you need to run, from the machine that can connect to the backend server/application. The custom DNS server is configured on a virtual network that can't resolve public domain names. I will now proceed to close this github issue here since this repo is for MS Docs specifically. Public domain name resolution might be required in scenarios where Application Gateway must reach out to external domains like OCSP servers or to check the certificates revocation status. to your account. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Can you please add reference to relevant Microsoft Docs page you are following? For testing purposes, you can create a self-signed certificate but you shouldn't use it for production workloads. Solution: Follow these steps to export and upload the trusted root certificate to Application Gateway. The application gateway then tries to connect to the server on the TCP port mentioned in the HTTP settings. with open ssl all looks okey i can see all chains. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. Not the answer you're looking for? 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. Once the public key has been exported, open the file. Select the setting that has the expired certificate, select, The NSG on the Application Gateway subnet is blocking inbound access to ports 65503-65534 (v1 SKU) or 65200-65535 (v2 SKU) from Internet. After the server starts responding 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. Azure Application Gateway with an internal APIM f. Select Save and verify that you can view the backend as Healthy. Already on GitHub? However, we need few details. here is the IP is your backend Application IP , it changes as per your backend pool you can use even use the hostname directly here. Does a password policy with a restriction of repeated characters increase security? Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. (LogOut/ I am currently experimenting with different ways to add the backend pools and heath probes to find a working configuration. Is that we have to follow the below step for resolution ? i raised ticket to Microsoft. Message: Body of the backend's HTTP response did not match the Message: The Common Name (CN) of the backend certificate doesn't match the host header of the probe. b. If you open your certificate with Notepad and it doesn't look similar to this, typically this means you didn't export it using the Base-64 encoded X.509(.CER) format. 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. 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. An issue with your configuration needs to be ruled out first. Create a free website or blog at WordPress.com. Thanks. If thats not a desired value, you should create a custom probe and associate it with the HTTP settings. Solution: Depending on the backend server's response code, you can take the following steps. Application Gateway WAF end to end SSL - Microsoft Community Hub To learn more visit https://aka.ms/authcertificatemismatch" I have some questions in regards to application gateway and need help with the same : Making sure your App Gateway has the authenticated cert installed on the HTTPs backend settings, with the appropriate Rules & Probe setup and bobs your uncle, I got full Health back, and all my sites were live and kicking. or is that all the backend pools has to serve the request for one application ? You'll see the Certificate Export Wizard. In this example, requests using TLS1.2 are routed to backend servers in Pool1 using end to end TLS. To do that, follow these steps: Message: The validity of the backend certificate could not be verified. Solution: If you receive this error, follow these steps: Check whether you can connect to the backend server on the port mentioned in the HTTP settings by using a browser or PowerShell. The text was updated successfully, but these errors were encountered: @EmreMARTiN, Thanks for the feedback. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. 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. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Azure Application Gateway 502 Web Server Backend Certificate not whitelisted. 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 , you can check yourself as below, Now lets discuss what exactly is the confusion here if we have multiple Chain Cert, Check this below 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. Please upload a valid certificate, Azure Application Gateway - check health on subset of backend nodes, Certificate error Azure Application Gateway, Azure Application gateway health check certificate mismatch, Azure Application Gateway Backend Setting Certificate error - ApplicationGatewayTrustedRootCertificateInvalidData, Redirect traffic of Azure Application Gateway based on health probe.