Let me set the scene. security issue in which Application Gateway marks the backend server as Unhealthy. You'll see the Certificate Export Wizard. 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 Already on GitHub? This will take some time to track down, fix, and the docs will need to be updated with limitations & best practices. Alternatively, you can do that through PowerShell/CLI. Every documentation page has a feedback section at the bottom. Which language's style guidelines should be used when writing code that is supposed to be called from another language? 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. Configure that certificate on your backend server. Our current setup includes app gateway v1 SKU integrated with app services having custom domain enabled. rev2023.5.1.43405. This configuration further secures end-to-end communication. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The section in blue contains the information that is uploaded to application gateway. I guess you need a Default SITE binding to a certificate, without SNI ticked. I have tried to upload root CA instead of using well-known CA and the issue persist. Now how do we find if my application/backendserver is sending the complete chain to AppGW? 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. 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. Access forbidden. Access the backend server directly and check the time taken for the server to respond on that page. Check whether the backend server requires authentication. Would you like to involve with it ? We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. If the domain is private or internal, try to resolve it from a VM in the same virtual network. This is the exact thing what we do when import .CER file in the HTTP Settings of the Application 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. 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. 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. 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. The HTTP setting of the gateway is configured as follow: I've provided, hopefully, the correct root certificate for the setting. Have done s_client -connect backend_ip:443 -servername backend_url -showcerts and found that Root CA is missing. 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. of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. Check the backend server's health and whether the services are running. 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? Cause: Application Gateway resolves the DNS entries for the backend pool at time of startup and doesn't update them dynamically while running. applications. 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. For example: I can confirm that it's NOT a general issue or bug of the product. b. Below is what happens during SSL negotiation when you have single chain cert and root in the AppGW. 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. here is the sample command you need to run, from the linux box that can connect to the backend application. 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. Cause: This error occurs when Application Gateway can't verify the validity of the certificate. 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. Enter any timeout value that's greater than the application response time, in seconds. 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. 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. 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. Otherwise, register and sign in. AppGW is a PaaS instance , by default you wont get access to the Applicaiton Gateway. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. 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. The application is listeing in port 443. Save the custom probe settings and check whether the backend health shows as Healthy now. 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. Now, this is the frustrating partwithin IIS, all of my sites are bound too each specified certificate (sharing a single cert across all the sites wont work for this scenario because of the difference in SSL and URL names), What the MSFT document (https://docs.microsoft.com/en-us/azure/application-gateway/application-gateway-end-to-end-ssl-powershell) fails to tell you, is that you need a Default SITE binding to a certificate, without SNI ticked. 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. Internal server error. I have two listeners and my issue has started on one of them when SSL certificate has been renewed. 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. 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. Your email address will not be published. here is what happens in in Multiple chain certificate. It is required for docs.microsoft.com GitHub issue linking. Version Independent ID: d85aa8fe-7270-d073-ea56-d1c0759383b8. Now you may ask why it works when you browse the backend directly through browser. Applicaiton works fine on the backend servers with 443 certificate from Digicert. OpenSSL> s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts here is the sample command you need to run, from the machine that can connect to the backend server/application. Learn more about Application Gateway diagnostics and logging. -No client certificate CA names sent To learn more, see our tips on writing great answers. If you have properly added the certificate, and the backend pool is pointing to the custom domain (not the azurewebsites.net domain), then your best options are to either try the V2 SKU, or open a support request to troubleshoot further. site bindings in IIS, server block in NGINX and virtual host in Apache. 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 . Visual Studio Code How to Change Theme ? 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. There is ROOT certificate on httpsettings. Azure Tip #9 Application Gateway Backend Certificate not whitelisted Error, Azure DevOps Fix for Access to path \SourceMapping.json is denied. I had to add a directive in the webserver conf file to enable presentation of the full trust chain. 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. Solution: Follow these steps to export and upload the trusted root certificate to Application Gateway. The -servername switch is used in shared hosting environments. Application Gateway is in an Unhealthy state. You can add this to the application gateway to allow your backend servers for end to end TLS encryption. @TravisCragg-MSFT: Thanks for checking this. If your backend is within a VNET not accessible from your local, the you run openssl from a Cloud Shell within VNET. thank you for sharing it . Expected:{HTTPStatusCode0} Received:{HTTPStatusCode1}. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Message: Time taken by the backend to respond to application gateway's health probe is more than the timeout threshold in the probe setting. Your email address will not be published. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. For the v1 SKU, authentication certificates are required, but for the v2 SKU trusted root certificates are required to allow the certificates. Azure Tip #11 Get Reports of ARM Deployments in Your Subscription. Check whetheraccess to the path is allowed on the backend server. In this article I am going to talk about one most common issue "backend certificate not whitelisted" 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. If they aren't, create a new rule to allow the connections. In this article I am going to talk about one most common issue "backend certificate not whitelisted" . 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. @JeromeVigne did you find a solution in your setup? You must have a custom probe to change the timeout value. The message displayed in the Details column provides more detailed insights about the issue, and based on those details, you can start troubleshooting the issue. Change), You are commenting using your Facebook account. To learn more visit https://aka.ms/authcertificatemismatch" I have some questions in regards to application gateway and need help with the same : You can add this github issue reference in your ticket so that the Azure support personnel can see the details without asking you to repeat these steps. 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 For example, run the following command: Test-NetConnection -ComputerName www.bing.com -Port 443. To create a custom probe, follow these steps. 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. A pfx certificate has also been added. Content: <---> A few things to check: a. backend server, it waits for a response from the backend server for a configured period. If the backend server response for the probe request contains the string unauthorized, it will be marked as Healthy. For testing purposes, you can create a self-signed certificate but you shouldn't use it for production workloads. For example: c. If it's not listening on the configured port, check your web server settings. Have a question about this project? During SSL negotiation , Client sends Client Hello and Server Responds with Server Hello with its Certificate to the Client. To Answer we need to understand what happens in any SSL/TLS negotiation. Ensure that you add the correct root certificate to whitelist the backend". 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. If Internet and private traffic are going through an Azure Firewall hosted in a secured Virtual hub (using Azure Virtual WAN Hub): a. 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/ Unfortunately I have to use the v1 for this set-up. 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: When you create a custom probe, you can mark a backend server as Healthy by matching a string from the response body. 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. 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. The authentication certificate is the public key of backend server certificates in Base-64 encoded X.509(.CER) format. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. 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. Error message shown - Backend server certificate is not whitelisted with Application Gateway. Something that you will see missing is microsft docs is having a default site binding to a SSL certificate without the SNI enabled. The output should show the full certificate chain of trust, importantly, the root certificate which is the one appgw requires. It is required for docs.microsoft.com GitHub issue linking. The exported certificate looks similar to this: If you open the exported certificate using Notepad, you see something similar to this example. Ensure that you add the correct root certificate to whitelist the backend. privacy statement. 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". 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 must be a registered user to add a comment. 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. You signed in with another tab or window. 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. Cause: After the TCP connection has been established and a TLS handshake is done (if TLS is enabled), Application Gateway will send the probe as an HTTP GET request to the backend server. After the server starts responding Do not edit this section. I did not find this error message listed here https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting. To learn more visit https://aka.ms/authcertificatemismatch". c. Check the user-defined routes (UDR) settings of Application Gateway and the backend server's subnet for any routing anomalies. 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. To increase the timeout value, follow these steps: Message: Application Gateway could not create a probe for this backend. -> Same certificate with private key from applicaton server. If the port mentioned is not the desired port, enter the correct port number for Application Gateway to connect to the backend server. privacy statement. 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. 2)How should we get this issue fixed ? If you're using a default probe, the host name will be set as 127.0.0.1. 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. Configure that certificate on your backend server. https://docs.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 Thanks. Ended up swapping to App Gateway V2 instead using the Trusted CA cert option on the backend http settings. To learn how to create NSG rules, see the documentation page. Message: Body of the backend's HTTP response did not match the Sign up for a free GitHub account to open an issue and contact its maintainers and the community. @sajithvasu I would continue to work with the support engineers while they look deeper into your authentication certificate. For File to Export, Browse to the location to which you want to export the certificate. How to organize your open apps in windows 11? Have raise case with Microsoft as unable to resolve that myself. After CA autohority re-created the certificate problem was gone. Verify that the response body in the Application Gateway custom probe configuration matches what's configured. We have this setup in multiple places created last year and it all works fine. Cause: Application Gateway checks whether the host name specified in the backend HTTP settings matches that of the CN presented by the backend servers TLS/SSL certificate. Solution: To resolve this issue, verify that the certificate on your server was created properly. @EmreMARTiN , following up to see if the support case resolved your issue. You can choose to use any other tool that is convenient. 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 (LogOut/ d. Check your OS firewall settings to make sure that incoming traffic to the port is allowed. Otherwise, it will be marked as Unhealthy with this message. Sorry my bad, this is actually now working - I just needed to have the CN in the certificate match with what was set in backend pool. Choose the destination manually as any internet-routable IP address like 1.1.1.1. with open ssl i should run the command on from local server ? How to Allow or Prevent Themes to Change Desktop Icons in Desktop Icon Settings in Windows 11? Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Your email address will not be published. error. Access the backend server locally or from a client machine on the probe path, and check the response body. Few days back , I had to update the Azure backend certificate for authentication in the Application Gateway and i started noticing this error, Backend server certificate is not whitelisted with Application Gateway.. But if this message is displayed, it suggests that Application Gateway couldn't successfully resolve the IP address of the FQDN entered. Is there a generic term for these trajectories? Default route advertised by the ExpressRoute/VPN connection to the virtual network over BGP: a. The application gateway then tries to connect to the server on the TCP port mentioned in the HTTP settings. The issue was on certificate. Create a free website or blog at WordPress.com. Document Details Now you have the authentication certificate/trusted root certificate in Base-64 encoded X.509(.CER) format. Thanks for this information. Export trusted root certificate (for v2 SKU): We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. 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. Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action in Windows 11. "Backend server certificate is not whitelisted with Application Gateway." Something that you will see missing is microsft docs is having a default site binding to a SSL certificate without the SNI enabled. To find out the reason, check OpenSSL diagnostics for the message associated with error code {errorCode}.
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