https://learn.microsoft.com/en-us/azure/application-gateway/certificates-for-backend-authentication#export-trusted-root-certificate-for-v2-sku, End-to-end TLS with the v2 SKU Do not edit this section. Message: The Common Name (CN) of the backend certificate doesn't match the host header of the probe. Message: Application Gateway could not connect to the backend. applications. 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. Required fields are marked *. Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. 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. To restart Application Gateway, you need to. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. site bindings in IIS, server block in NGINX and virtual host in Apache. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. probe setting. 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. @sajithvasu This lab takes quite a long time to set up! b. To learn how to create NSG rules, see the documentation page. 10.0.0.4 = IP of backend server (if using DNS ensure it points to backend server and not the public IP of appgw). Ensure that you add the correct root certificate to whitelist the backend". I will post any updates here as soon as I have them. 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 Application Gateway health probe error with "Backend server 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). 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. with your vendor and update the server settings with the new By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. security issue in which Application Gateway marks the backend server as Unhealthy. See Configure end to end TLS by using Application Gateway with PowerShell. Configure that certificate on your backend server. 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. I did not find this error message listed here https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting. If that's not the desired host name for your website, you must get a certificate for that domain or enter the correct host name in the custom probe or HTTP setting configuration. From your TLS/SSL certificate, export the public key .cer file (not the private key). 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. Azure Tip #11 Get Reports of ARM Deployments in Your Subscription. Thanks. What was the resolution? If Pick hostname from backend address is set in the HTTP settings, the backend address pool must contain a valid FQDN. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. Your email address will not be published. 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. Current date is not within the "Valid from" and "Valid to" date range on the certificate. PS : Dont forget to upload the CER file to the HTTP settings in ApplicationGateway before you do the Health Check. 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 default probe request is sent in the format of ://127.0.0.1:. b. 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. AppGW is a PaaS instance , by default you wont get access to the Applicaiton Gateway. 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. Sign in To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If you do not have a support plan, please let me know. 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. Save the custom probe settings and check whether the backend health shows as Healthy now. 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? @sajithvasu My apologies for this taking a long time, but there are some strange issues here(as you have already discovered). 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. 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"). 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. @EmreMARTiN , following up to see if the support case resolved your issue. b. Message: Body of the backend's HTTP response did not match the Additionally, if you want to use a different text editor, understand that some editors can introduce unintended formatting in the background. How to Allow or Prevent Themes to Change Desktop Icons in Desktop Icon Settings in Windows 11? We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. Our backend web server is running Apache with multiple HTTPS sites on the same server and the issue we face is regardless of the HTTPS . 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. If Application Gateway can't establish a TCP session on the port specified, the probe is marked as Unhealthy with this message. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. 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. Adding the certificate ensures that the application gateway communicates only with known back-end instances. 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. What are the advantages of running a power tool on 240 V vs 120 V? (These steps are for Windows clients.). It is required for docs.microsoft.com GitHub issue linking. More info about Internet Explorer and Microsoft Edge, Export trusted root certificate (for v2 SKU), Overview of TLS termination and end to end TLS with Application Gateway, Application Gateway diagnostics and logging. You signed in with another tab or window. 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. 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. In that case, I suggest you to create an Azure Support ticket to take a closer look at internal diagnostics of your app gateway instance considering it's still occurring after troubleshooting. 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. Change the host name or path parameter to an accessible value. Failing endpoint is missing root CA as working one has it. Ensure that you add the correct root certificate to whitelist the backend". 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. Cause: After Application Gateway sends an HTTP(S) probe request to the Let me set the scene. 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