We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. Received response body doesn't contain {string}. To Answer we need to understand what happens in any SSL/TLS negotiation. An issue with your configuration needs to be ruled out first. Ensure that you add the correct root certificate to whitelist the backend. Your email address will not be published. Trusted root certificate mismatch I will now proceed to close this github issue here since this repo is for MS Docs specifically. 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. For example, check whether the database has any issues that might trigger a delay in response. I had to add a directive in the webserver conf file to enable presentation of the full trust chain. The custom DNS server is configured on a virtual network that can't resolve public domain names. To learn more visit https://aka.ms/authcertificatemismatch". You'll see the Certificate Export Wizard. 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. So, I created a default site pointed it to wwwroot, and selected one of my already installed certificates (you can probably PowerShell an SSL for this tbh, but I chose to re-use an already existing one) you dont have to supply a hostname, just a dummy site with an authenticated cert on port 443. For example, http://127.0.0.1:80 for an HTTP probe on port 80. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. 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. 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. @TravisCragg-MSFT : Did you find out anything? 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. An Azure service that provides a platform-managed, scalable, and highly available application delivery controller as a service. 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. Backend Health page on the Azure portal. Select the root certificate and then select View Certificate. Message: The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. 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. Follow steps 1a and 1b to determine your subnet. 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. Additionally, if you want to use a different text editor, understand that some editors can introduce unintended formatting in the background. Let me know here if you face any issue reaching Azure support or if you do not have any support plan for your subscription. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. or from external over WAF ? site bindings in IIS, server block in NGINX and virtual host in Apache. Document Details Thanks. what we are doing is actually trying to simulate the Linux box as AppGW as if that machine is trying probe to the backend server as AppGW. Save the custom probe settings and check whether the backend health shows as Healthy now. Trusted root certificate is required to allow backend instances in application gateway v2 SKU. Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action in Windows 11. b. Sign in This approach is useful in situations where the backend website needs authentication. Can you recreate this scenario in your lab using multi-site and custom domain on appservices with SNI bind SSL and cert issued by different CA than Microsoft and not the default azurewebsites.net and you may hit this issue? You can verify by using the Connection Troubleshoot option in the Application Gateway portal. Do not edit this section. Have a question about this project? Check the network security group (NSG) settings of the backend server's network adapter and subnet and whether inbound connections to the configured port are allowed. I will wait for your response. Now you have the authentication certificate/trusted root certificate in Base-64 encoded X.509(.CER) format. For example: c. If it's not listening on the configured port, check your web server settings. Sure I would be glad to get involved if needed. https://learn.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. Export trusted root certificate (for v2 SKU): Adding the certificate ensures that the application gateway communicates only with known back-end instances. If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? 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 there's a custom DNS server configured on the virtual network, verify that the servers can resolve public domains. Is that we have to follow the below step for resolution ? The chain looks ok to me. Otherwise please share the message in that scenario without adding root explicitly. OpenSSL> s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts The exported certificate looks similar to this: If you open the exported certificate using Notepad, you see something similar to this example. Access forbidden. An existing backend certificate is required to generate the authentication certificates or trusted root certificates required for allowing backend instances with Application Gateway. Ensure that you add the correct root certificate to whitelist the backend". Azure Application Gateway with an internal APIM 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. I will post the root cause summary once there is an outcome from your open support case. Well occasionally send you account related emails. Ensure that you create a default website in the IIS with-in the VM without the SNI enabled and you should not see this error. Application Gateway is in an Unhealthy state. b. to your account. For example: Find out more about the Microsoft MVP Award Program. Azure Applicaiton Gateway V2 Certification Issue #62578 - Github Thanks for contributing an answer to Stack Overflow! Horizontal and vertical centering in xltabular, one or more moons orbitting around a double planet system, Embedded hyperlinks in a thesis or research paper, Proving that Every Quadratic Form With Only Cross Product Terms is Indefinite. Something that you will see missing is microsft docs is having a default site binding to a SSL certificate without the SNI enabled. 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. Check whether the host name path is accessible on the backend server. Backend Authentication certificate issue #40941 - Github -> it has been taken from application servers by exporting as documented on Microsoft docs for WAF v2. Check whether your UDR has a default route (0.0.0.0/0) with the next hop not set as Internet: a. 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. what we are doing is actually trying to simulate the Linux box as AppGW as if that machine is trying probe to the backend server as AppGW. When we check the certificate with the openssl there were following errors: The output should show the full certificate chain of trust, importantly, the root certificate which is the one appgw requires. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Configure that certificate on your backend server. i had this issue for client and split multiple vms ! Service unavailable. To do the whitlisting, you will need to export APIM SSL certificate into a Base-64 encoded (CER) format, and apply the exported certificate in (Backend authentication certificates) under the Application Gateway's HTTP settings configured for the APIM. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. 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. Ended up swapping to App Gateway V2 instead using the Trusted CA cert option on the backend http settings. Now you may ask why it works when you browse the backend directly through browser. If you can't connect on the port from your local machine as well, then: a. Ensure that you add the correct root certificate to whitelist the backend". 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. To ensure the application gateway can send traffic to the backend pool via an Azure Firewall in the Virtual WAN hub, configure the following user defined route: Address Prefix: Backend pool subnet Default route advertised by the ExpressRoute/VPN connection to the virtual network over BGP: a. 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. Solution: Depending on the backend server's response code, you can take the following steps. 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? Asking for help, clarification, or responding to other answers. Does a password policy with a restriction of repeated characters increase security? I just set it up and cannot get the health probe for HTTPS healthy. certificate. If you're aware of the application's behavior and it should respond only after the timeout value, increase the timeout value from the custom probe settings. here is the sample command you need to run, from the linux box that can connect to the backend application. 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. 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. For more information about how to extract and upload Trusted Root Certificates in Application Gateway, see Export trusted root certificate (for v2 SKU). Visual Studio Code How to Change Theme ? with open ssl i should run the command on from local server ? https://docs.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. Move to the Certification Path view to view the certification authority. Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. 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. Posted in Azure Tagged 502webserver, Azure, azure502, azureapplicationgateway, azurecertificate, azurewaf, backend certificate not whitelisted Post navigation Azure Cyber Security: Protect & Secure Your Cloud Infrastructure @JeromeVigne did you find a solution in your setup? 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/ 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. If you can resolve it, restart Application Gateway and check again. 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 will post any updates here as soon as I have them. 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 . Hope this helps. I have two listeners and my issue has started on one of them when SSL certificate has been renewed. If you've already registered, sign in. This verification is Standard_v2 and WAF_v2 SKU (V2) behavior. 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. Sign in Alternatively, you can do that through PowerShell/CLI. Required fields are marked *. 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. Configure that certificate on your backend server. Traffic should still be routing through the Application Gateway without issue. Connect and share knowledge within a single location that is structured and easy to search. For File to Export, Browse to the location to which you want to export the certificate. Sign in to the machine where your application is hosted. You must have a custom probe to change the timeout value. The root certificate is a Base-64 encoded X.509(.CER) format root certificate from the backend server certificates. Just FYI. How to Allow or Prevent Themes to Change Desktop Icons in Desktop Icon Settings in Windows 11? 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). 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. b. Our current setup includes app gateway v1 SKU integrated with app services having custom domain enabled. When i check health probe details are following: After CA autohority re-created the certificate problem was gone. This month for new environment build we started encountering this problem. backend server, it waits for a response from the backend server for a configured period. Client has renewed cert which is issued by GlobalSign and one of the listeners started to fail with same error. I had this same issue. For example, run the following command: Test-NetConnection -ComputerName www.bing.com -Port 443. . End-to-end SSL with Application Gateway v2 requires the backend server's certificate to be verified in order to deem the server Healthy. 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. 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. Failing endpoint is missing root CA as working one has it. It is required for docs.microsoft.com GitHub issue linking. Content Source:<---> Here is a blog post to fix the issue. Message: The root certificate of the server certificate used by the backend doesn't match the trusted root certificate added to the application gateway. Otherwise, it will be marked as Unhealthy with this message. here is the sample command you need to run, from the machine that can connect to the backend server/application. Change the host name or path parameter to an accessible value. Best practices and the latest news on Microsoft FastTrack, The employee experience platform to help people thrive at work, Expand your Azure partner-to-partner network, Bringing IT Pros together through In-Person & Virtual events. Message: The server certificate used by the backend is not signed by a well-known Certificate Authority (CA). Is there a generic term for these trajectories? 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. Configure that certificate on your backend server. Or, you can use Azure PowerShell, CLI, or REST API. How to connect to new Wi-Fi in Windows 11? I will wait for the outcome. How to organize your open apps in windows 11? Move to the Details view and click Copy to File At this point, you've extracted the details of the root certificate from the backend certificate. b. If you can resolve the IP address, there might be something wrong with the DNS configuration in the virtual network. @TravisCragg-MSFT : Thank you! Now how do we find if my application/backendserver is sending the complete chain to AppGW? 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. 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. Check whether the NSG settings of the Application Gateway subnet allow outbound public and private traffic, so that a connection can be made. I did not find this error message listed here https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting. If you are not familiar with Cloud Shell, it allows you to access bash or powershell from your browser to run commands within your Azure subscription https://docs.microsoft.com/en-us/azure/cloud-shell/overview. If the server returns any other status code, it will be marked as Unhealthy with this message. The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. Your certificate is successfully exported. -No client certificate CA names sent And each pool has 2 servers . To find out the reason, check OpenSSL diagnostics for the message associated with error code {errorCode}. Azure Application Gateway health probe error with "Backend server 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. We initially faced an issue with the certificate on the backend server which has since been sorted out by MS Support. 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. Solution: Follow these steps to export and upload the trusted root certificate to Application Gateway. To restart Application Gateway, you need to. The application gateway then tries to connect to the server on the TCP port mentioned in the HTTP settings. 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. When calculating CR, what is the damage per turn for a monster with multiple attacks? Which was the first Sci-Fi story to predict obnoxious "robo calls"? For the v1 SKU, authentication certificates are required, but for the v2 SKU trusted root certificates are required to allow the certificates. Otherwise, register and sign in. The gateway listener is configured to accept HTTPS connections. 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. thank you for sharing it . Make sure the UDR isn't directing the traffic away from the backend subnet. 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 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. Open your Application Gateway HTTP settings in the portal. Azure Tip #11 Get Reports of ARM Deployments in Your Subscription. 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. Follow steps 1-11 in the preceding method to upload the correct trusted root certificate to Application Gateway. 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. The -servername switch is used in shared hosting environments. "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. 10.0.0.4 = IP of backend server (if using DNS ensure it points to backend server and not the public IP of appgw). How do I bypass Microsoft account login in Windows11? In Azure docs, it is clearly documented that you dont have import Auth certificate in HTTP settings of the backend if your backend application has Global trusted certificate. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. @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. here is what happens in in Multiple chain certificate. Cause: When you create a custom probe, you can mark a backend server as Healthy by matching a string from the response body. Would you like to involve with it ? Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Applicaiton works fine on the backend servers with 443 certificate from Digicert. c. Check to see if there are any default routes (0.0.0.0/0) with the next hop not set as Internet. It is required for docs.microsoft.com GitHub issue linking. Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. Not the answer you're looking for? How to Restart Windows Explorer Process in Windows 11? If you do not have a support plan, please let me know. 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. Next hop: Azure Firewall private IP address. Already on GitHub? to your account. Check whether the backend server requires authentication. You signed in with another tab or window. Change). Enter any timeout value that's greater than the application response time, in seconds. Check that the backend responds on the port used for the probe. privacy statement. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. This configuration further secures end-to-end communication. Once the public key has been exported, open the file. Certificates signed by well known CA authorities whose CN matches the host name in the HTTP backend settings do not require any additional step for end to end TLS to work. error. Please log in using one of these methods to post your comment: You are commenting using your WordPress.com account. I will clean-up some of my older comments to keep it generic to all since the issue has been identified. I can confirm that it's NOT a general issue or bug of the product. or is that all the backend pools has to serve the request for one application ? By clicking Sign up for GitHub, you agree to our terms of service and After the server starts responding The backend certificate can be the same as the TLS/SSL certificate or different for added security. If you create the issue from there, the required details will be auto-populated. Allow the backend on the Application Gateway by uploading the root certificate of the server certificate used by the backend. Issue within certification chain using azure application gateway If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Azure Application Gateway 502 Web Server Backend Certificate not whitelisted. During SSL negotiation , Client sends Client Hello and Server Responds with Server Hello with its Certificate to the Client. Azure Application Gateway: 502 error due to backend certificate not Check whetheraccess to the path is allowed on the backend server. Check to see if a UDR is configured. To learn how to create NSG rules, see the documentation page. @TravisCragg-MSFT: Thanks for checking this. Select the root certificate and click on View Certificate. xcolor: How to get the complementary color. 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. You should see the root certificate details. If Application Gateway can't establish a TCP session on the port specified, the probe is marked as Unhealthy with this message. To learn more visit - https://aka.ms/UnknownBackendHealth. On the Subnets tab of your virtual network, select the subnet where Application Gateway has been deployed. If the backend health is shown as Unknown, the portal view will resemble the following screenshot: This behavior can occur for one or more of the following reasons: Check whether your NSG is blocking access to the ports 65503-65534 (v1 SKU) or 65200-65535 (v2 SKU) from Internet: a.
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