EDIT: Turned out I uploaded wrong pfx compared to the backend server. Check whether your UDR has a default route (0.0.0.0/0) with the next hop not set as Internet: a. with your vendor and update the server settings with the new 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. i have configured a Azure Application gateway (v2) and there is one backend servers. Let me know here if you face any issue reaching Azure support or if you do not have any support plan for your subscription. To learn more visit https://aka.ms/authcertificatemismatch" I have some questions in regards to application gateway and need help with the same : 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. 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. 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 there's a custom probe associated with the HTTP settings, SNI will be set from the host name mentioned in the custom probe configuration. 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. Now you have the authentication certificate/trusted root certificate in Base-64 encoded X.509(.CER) format. @TravisCragg-MSFT: Thanks for checking this. 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. For File to Export, Browse to the location to which you want to export the certificate. Do not edit this section. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. To ensure the application gateway can send traffic directly to the Internet, configure the following user defined route: Address prefix: 0.0.0.0/0 The backend certificate can be the same as the TLS/SSL certificate or different for added security. 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. -No client certificate CA names sent Have a question about this project? If thats not a desired value, you should create a custom probe and associate it with the HTTP settings. A few things to check: a. Expected:{HTTPStatusCode0} Received:{HTTPStatusCode1}. During SSL negotiation , Client sends "Client Hello" and Server Responds with "Server Hello" with its Certificate to the Client. 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. Follow steps 1-10 in the preceding section to upload the correct trusted root certificate to Application Gateway. 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. If you're using a default probe, the host name will be set as 127.0.0.1. 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 ? Something that you will see missing is microsft docs is having a default site binding to a SSL certificate without the SNI enabled. 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. The current data must be within the valid from and valid to range. Ensure that you add the correct root certificate to whitelist the backend. craigclouditpro your a lifesaver thanks for posting this friend ! For example, you can configure Application Gateway to accept "unauthorized" as a string to match. Or, you can use Azure PowerShell, CLI, or REST API. In this example, we'll use a TLS/SSL certificate for the backend certificate, export its public key and then export the root certificate of the trusted CA from the public key in base64 encoded format to get the trusted root certificate. To learn more visit - https://aka.ms/UnknownBackendHealth. The v2 SKU is not an option at the moment due to lack of UDR support. Make sure https probe is configured correctly as well. xcolor: How to get the complementary color. 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. 7 19 comments Add a Comment Nillsf 4 yr. ago Cause: If the backend pool is of type IP Address, FQDN or App Service, Application Gateway resolves to the IP address of the FQDN entered through DNS (custom or Azure default). This article describes the symptoms, cause, and resolution for each of the errors shown. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. End-to-end SSL with Application Gateway v2 requires the backend server's certificate to be verified in order to deem the server Healthy. Allow the backend on the Application Gateway by uploading the root certificate of the server certificate used by the backend. How do I bypass Microsoft account login in Windows11? How to Restart Windows Explorer Process in Windows 11? Application Gateway must be restarted after any modification to the backend server DNS entries to begin to use the new IP addresses. How to organize your open apps in windows 11? 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"). The other one which certificate is still valid and does not need renewal is green. "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 Application Gateway: 502 error due to backend certificate not Configuration details on Applicaiton Gateway: i am stuck with that issue, i am thinking maybe it can be a bug but can not be sure. here is the sample command you need to run, from the machine that can connect to the backend server/application. Check whether the host name path is accessible on the backend server. OpenSSL> s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts Your email address will not be published. It is required for docs.microsoft.com GitHub issue linking. The default route is advertised by an ExpressRoute/VPN connection to a virtual network over BGP. If it's a self-signed certificate, you must generate a valid certificate and upload the root certificate to the Application Gateway HTTP settings. Adding the certificate ensures that the application gateway communicates only with known back-end instances. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Azure Application Gateway health probe error with "Backend server certificate is not whitelisted with Application Gateway", When AI meets IP: Can artists sue AI imitators? For example: c. If it's not listening on the configured port, check your web server settings. Parabolic, suborbital and ballistic trajectories all follow elliptic paths. Already on GitHub? More info about Internet Explorer and Microsoft Edge, https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting, https://learn.microsoft.com/en-us/azure/application-gateway/certificates-for-backend-authentication#export-trusted-root-certificate-for-v2-sku, https://learn.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. For more information on SNI behavior and differences between v1 and v2 SKU, see Overview of TLS termination and end to end TLS with Application Gateway. @TravisCragg-MSFT : Did you find out anything? For example, http://127.0.0.1:80 for an HTTP probe on port 80. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. I will post the root cause summary once there is an outcome from your open support case. How to Change Network Location to Private, Public, or Domain in Windows 11? Check whether the virtual network is configured with a custom DNS server. Azure Applicaiton Gateway V2 Certification Issue #62578 - Github thank you for sharing it . d. Otherwise, change the next hop to Internet, select Save, and verify the backend health. The Standard and WAF SKU (v1) Server Name Indication (SNI) is set as the FQDN in the backend pool address. SAP on Azure: Azure Application Gateway Web Application Firewall (WAF You can add this to the application gateway to allow your backend servers for end to end TLS encryption. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. Azure Application Gateway "502 Web Server" - Backend Certificate not If you're using Azure default DNS, check with your domain name registrar about whether proper A record or CNAME record mapping has been completed. After CA autohority re-created the certificate problem was gone. Change the host name or path parameter to an accessible value. Ensure that you add the correct root certificate to allowlist the backend. For more information about how to extract and upload Trusted Root Certificates in Application Gateway, see Export trusted root certificate (for v2 SKU). Select the root certificate and click on View Certificate. certificate. Learn more about Application Gateway diagnostics and logging. I had to add a directive in the webserver conf file to enable presentation of the full trust chain. Backend Health page on the Azure portal. 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. This will take some time to track down, fix, and the docs will need to be updated with limitations & best practices. The -servername switch is used in shared hosting environments. 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" 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 is the exact thing what we do when import .CER file in the HTTP Settings of the 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). b. Our current setup includes app gateway v1 SKU integrated with app services having custom domain enabled. 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. By clicking Sign up for GitHub, you agree to our terms of service and 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. You signed in with another tab or window. I will wait for the outcome. -Verify return code: 19 (self signed certificate in certificate chain). Cause: After Application Gateway sends an HTTP(S) probe request to the @EmreMARTiN you can run openssl from your local machine pointing to your backend, not external over WAF. to your account. I have the same issue, Root cert is DigiCert. successfully, Application Gateway resumes forwarding the requests. 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. Create a free website or blog at WordPress.com. ID: <---> 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. User without create permission can create a custom object from Managed package using Custom Rest API, the Allied commanders were appalled to learn that 300 glider troops had drowned at sea. Save the custom probe settings and check whether the backend health shows as Healthy now. Make sure the UDR isn't directing the traffic away from the backend subnet. I will clean-up some of my older comments to keep it generic to all since the issue has been identified. Does a password policy with a restriction of repeated characters increase security? i raised ticket to Microsoft. Issue within certification chain using azure 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 . For new setup, we have noticed that app gateway back-end becomes unhealthy. Set the destination port as anything, and verify the connectivity. 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. Enter any timeout value that's greater than the application response time, in seconds. To troubleshoot this issue, check the Details column on the Backend Health tab. This post has been republished via RSS; it originally appeared at: New blog articles in Microsoft Tech Community. For the v1 SKU, authentication certificates are required, but for the v2 SKU trusted root certificates are required to allow the certificates. Which was the first Sci-Fi story to predict obnoxious "robo calls"? 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. Thanks for contributing an answer to Stack Overflow! 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. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. Can you please add reference to relevant Microsoft Docs page you are following? b. Access forbidden. Change), You are commenting using your Facebook account. Azure Application Gateway: 502 error due to backend certificate not For details on this Openssl command you can refer toTroubleshoot backend health issues in Azure Application Gateway | Microsoft Docs , Look for the sub topic Trusted root certificate mismatch. I am 3 backend pools . Export trusted root certificate (for v2 SKU): 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. Do not edit this section. Current date is not within the "Valid from" and "Valid to" date range on the certificate. You can choose to use any other tool that is convenient. 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. Message: Status code of the backend's HTTP response did not match the probe setting. 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. 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. If Application Gateway can't establish a TCP session on the port specified, the probe is marked as Unhealthy with this message. Otherwise, register and sign in. Connect and share knowledge within a single location that is structured and easy to search. https://docs.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. (LogOut/ If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? 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. @EmreMARTiN , you mentioned your backend certificate is from "Digicert" which is already a well-known trusted CA. Application Gateway is in an Unhealthy state. Did the drapes in old theatres actually say "ASBESTOS" on them? Well occasionally send you account related emails. Otherwise, it will be marked as Unhealthy with this message. If Pick hostname from backend address is set in the HTTP settings, the backend address pool must contain a valid FQDN. Cause: When you create a custom probe, you can mark a backend server as Healthy by matching a string from the response body. For example: Solution: If your TLS/SSL certificate has expired, renew the certificate c. If the next hop is virtual network gateway, there might be a default route advertised over ExpressRoute or VPN. Ensure that you add the correct root certificate to whitelist the backend". If they aren't, create a new rule to allow the connections. If you can resolve the IP address, there might be something wrong with the DNS configuration in the virtual network. Required fields are marked *. Passing negative parameters to a wolframscript. The root certificate is a Base-64 encoded X.509(.CER) format root certificate from the backend server certificates. Internal server error. b. Required fields are marked *. Was the error "exactly" the same before you explicitly added the exported root rather than relying on "Digicert" as known authority? document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Azure Application Gateway 502 Web Server Backend Certificate not whitelisted. This configuration further secures end-to-end communication. For details on this Openssl command you can refer toTroubleshoot backend health issues in Azure Application Gateway | Microsoft Docs , Look for the sub topic "Trusted root certificate mismatch". Walkthrough: Configuring end-to-end TLS with Application Gateway and PS : Dont forget to upload the CER file to the HTTP settings in ApplicationGateway before you do the Health Check. I will let you know what I find. Well occasionally send you account related emails. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. Cause: Application Gateway resolves the DNS entries for the backend pool at time of startup and doesn't update them dynamically while running. Failed health probe in Azure Application Gateway : r/AZURE - Reddit 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. Cause: Every certificate comes with a validity range, and the HTTPS connection won't be secure unless the server's TLS/SSL certificate is valid. 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. 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. 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. Currently we are seeing issues with app gateway backend going unhealthy due to backend auth cert. 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.