I had to add a directive in the webserver conf file to enable presentation of the full trust chain. An issue with your configuration needs to be ruled out first. 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. Configure that certificate on your backend server. The -servername switch is used in shared hosting environments. To troubleshoot this issue, check the Details column on the Backend Health tab. 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. 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. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. The output should show the full certificate chain of trust, importantly, the root certificate which is the one appgw requires. This will take some time to track down, fix, and the docs will need to be updated with limitations & best practices. Sign in to the machine where your application is hosted. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? 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. Access forbidden. If the backend server response for the probe request contains the string unauthorized, it will be marked as Healthy. b. 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. This article describes the symptoms, cause, and resolution for each of the errors shown. here is the sample command you need to run, from the machine that can connect to the backend server/application. successfully, Application Gateway resumes forwarding the requests. 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. Nice article mate! 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. If you've already registered, sign in. Connect and share knowledge within a single location that is structured and easy to search. I will let you know what I find. 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. here is what happens in in Multiple chain certificate. For example, you can configure Application Gateway to accept "unauthorized" as a string to match. 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. 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. Message: The root certificate of the server certificate used by the backend doesn't match the trusted root certificate added to the application gateway. Thank you everyone. Let me know here if you face any issue reaching Azure support or if you do not have any support plan for your subscription. b. Trusted root certificate is required to allow backend instances in application gateway v2 SKU. probe setting. Message: The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. Well occasionally send you account related emails. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Application Gateway is in an Unhealthy state. Passing negative parameters to a wolframscript. 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" OpenSSL> s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts 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. Sub-service: <---> @EmreMARTiN you can run openssl from your local machine pointing to your backend, not external over WAF. 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. 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 ensure the application gateway can send traffic directly to the Internet, configure the following user defined route: Address prefix: 0.0.0.0/0 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. 7 19 comments Add a Comment Nillsf 4 yr. ago 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. 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. How to Change Network Location to Private, Public, or Domain in Windows 11? 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. 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 . 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. Thanks. Do not edit this section. However, we need few details. 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 the backend server doesn't multiple chain certificate and if your backend application/server sends only the leaf the certificate , AppGW . For testing purposes, you can create a self-signed certificate but you shouldn't use it for production workloads. If you want Application Gateway to probe on a different protocol, host name, or path and to recognize a different status code as Healthy, configure a custom probe and associate it with the HTTP settings. 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. The other one which certificate is still valid and does not need renewal is green. I had this same issue. Resolution: Check why the backend server or application isn't responding within the configured timeout period, and also check the application dependencies. 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 The exported certificate looks similar to this: If you open the exported certificate using Notepad, you see something similar to this example. @EmreMARTiN , following up to see if the support case resolved your issue. 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. d. To check the effective routes and rules for a network adapter, you can use the following PowerShell commands: If you don't find any issues with NSG or UDR, check your backend server for application-related issues that are preventing clients from establishing a TCP session on the ports configured. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Message: The Common Name (CN) of the backend certificate doesn't match the host header of the probe. I will now proceed to close this github issue here since this repo is for MS Docs specifically. 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. to your account. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. 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". Follow steps 1-11 in the preceding method to upload the correct trusted root certificate to Application Gateway. 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. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Sharing best practices for building any app with .NET. Change). 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 . 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. 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. 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. A few things to check: a. 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. 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 applications. Verify that the response body in the Application Gateway custom probe configuration matches what's configured. Now how can find if my application sending the complete chain , the easy way to find is running openssl from either windows client or Linux client which is present in the same network/subnet of the backend application. During SSL negotiation , Client sends Client Hello and Server Responds with Server Hello with its Certificate to the Client. backend server, it waits for a response from the backend server for a configured period. 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. @JeromeVigne did you find a solution in your setup? 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. If it's not, the certificate is considered invalid, and that will create a Check that the backend responds on the port used for the probe. 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. Solution: Follow these steps to export and upload the trusted root certificate to Application Gateway. 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. -verify error:num=19:self signed certificate in certificate chain To find out the reason, check OpenSSL diagnostics for the message associated with error code {errorCode}. It worked fine for me with the new setup in the month of September with V1 SKU. Below is what happens during SSL negotiation when you have single chain cert and root in the AppGW. 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. Message: Backend certificate is invalid. Internal server error. 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? If you do not have a support plan, please let me know. For example, run the following command: Test-NetConnection -ComputerName www.bing.com -Port 443. In this article I am going to talk about one most common issue "backend certificate not whitelisted" document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. You can verify by using the Connection Troubleshoot option in the Application Gateway portal. End-to-end SSL with Application Gateway v2 requires the backend server's certificate to be verified in order to deem the server Healthy. 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. Message: Body of the backend's HTTP response did not match the Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action in Windows 11. privacy statement. If the port mentioned is not the desired port, enter the correct port number for Application Gateway to connect to the backend server. 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/ to your account. @sajithvasu I would continue to work with the support engineers while they look deeper into your authentication certificate. The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. Azure Tip #3 What is Scale up and Scale Out ? You'll see the Certificate Export Wizard. 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. (LogOut/ Note that this .CER file must match the certificate (PFX) deployed at the backend application. Was the error "exactly" the same before you explicitly added the exported root rather than relying on "Digicert" as known authority? Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. The root certificate is a Base-64 encoded X.509(.CER) format root certificate from the backend server certificates. Check whetheraccess to the path is allowed on the backend server. At the time of writing the Application Gateway doesnt support uploading the Certificates directly into Key Vault, hence extracting the string into .txt and dumping it in Key Vault Secrets. f. Select Save and verify that you can view the backend as Healthy. It is required for docs.microsoft.com GitHub issue linking. 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. This usually happens when the FQDN of the backend has not been entered correctly.. Let me set the scene. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Received response body doesn't contain {string}. 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. I did not find this error message listed here https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting. Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. 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. 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. Every documentation page has a feedback section at the bottom. For File to Export, Browse to the location to which you want to export the certificate. 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. 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. Azure Tip #9 Application Gateway Backend Certificate not whitelisted Error, Azure DevOps Fix for Access to path \SourceMapping.json is denied. @krish-gh actually it was actually what have i tried firstly but sitouiotion was same. To do that, follow these steps: Message: The validity of the backend certificate could not be verified. After CA autohority re-created the certificate problem was gone. If you create the issue from there, the required details will be auto-populated. Hope this helps. Azure Tip #7 What are the Storage Tiers in Azure ? 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. Message: The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. You should see the root certificate details. I am 3 backend pools . Is that we have to follow the below step for resolution ? 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. Your certificate is successfully exported. Create a free website or blog at WordPress.com. Currently we are seeing issues with app gateway backend going unhealthy due to backend auth cert. Otherwise, register and sign in. How to Restart Windows Explorer Process in Windows 11? For more information about how to extract and upload Trusted Root Certificates in Application Gateway, see Export trusted root certificate (for v2 SKU). I guess you need a Default SITE binding to a certificate, without SNI ticked. Your email address will not be published. same situation as @JeromeVigne: App Gateway v1 as front-end to API Management, the health probe is unhealthy with the "Backend server certificate is not whitelisted with Application Gateway . GitHub Login: <---> I am currently experimenting with different ways to add the backend pools and heath probes to find a working configuration. 10.0.0.4 = IP of backend server (if using DNS ensure it points to backend server and not the public IP of appgw). To learn more visit https://aka.ms/authcertificatemismatch". To learn more visit https://aka.ms/authcertificatemismatch" I have some questions in regards to application gateway and need help with the same : 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. 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. Posted in Azure Tagged 502webserver, Azure, azure502, azureapplicationgateway, azurecertificate, azurewaf, backend certificate not whitelisted Post navigation Azure Cyber Security: Protect & Secure Your Cloud Infrastructure More info about Internet Explorer and Microsoft Edge, Export authentication certificate (for v1 SKU), Configure end to end TLS by using Application Gateway with PowerShell, Export authentication certificate from a backend certificate (for v1 SKU), Export trusted root certificate from a backend certificate (for v2 SKU), To obtain a .cer file from the certificate, open. Ensure that you add the correct root certificate to whitelist the backend". This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. Select the root certificate and click on View Certificate. Ensure that you add the correct root certificate to whitelist the backend. 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. But if this message is displayed, it suggests that Application Gateway couldn't successfully resolve the IP address of the FQDN entered. b. Or, if Pick host name from backend address is mentioned in the HTTP settings, where the backend address pool contains a valid FQDN, this setting will be applied. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. https://docs.microsoft.com/en-us/azure/application-gateway/ssl-overview#end-to-end-tls-with-the-v2-sku. 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. 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. d. Otherwise, change the next hop to Internet, select Save, and verify the backend health. 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"). This can create problems when uploaded the text from this certificate to Azure. 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. This post has been republished via RSS; it originally appeared at: New blog articles in Microsoft Tech Community. 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. The backend certificate can be the same as the TLS/SSL certificate or different for added security. Export trusted root certificate (for v2 SKU): Next hop: Internet. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. Now you may ask why it works when you browse the backend directly through browser. @sajithvasu This lab takes quite a long time to set up! Can you post the output please after masking any sensitive info? Follow steps 1a and 1b to determine your subnet. On the Export File Format page, select Base-64 encoded X.509 (.CER)., and then click Next. If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? The authentication certificate is the public key of backend server certificates in Base-64 encoded X.509 (.CER) format. New blog articles in Microsoft Tech Community, Troubleshoot backend health issues in Azure Application Gateway | Microsoft Docs, Set up Granular Delegated Admin Privileges in Microsoft 365 Lighthouse, Data Mapper Patterns: Conditional Mapping, Windows Server Summit 2022: Modernize your Apps with Windows Containers and AKS, Kubernetes External DNS for Azure DNS & AKS, Update: Addressing Karis Law and Ray Baums Act with Microsoft Teams phone system, SSIS Always on AG (Availability Group) and Error Please Create a Master Key, Azure Marketplace new offers January 4, 2023. (Ep. 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. 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. To learn more, see our tips on writing great answers. If you don't mind can you please post the summary of the root here to help people who might face similar issue. 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. For example, http://127.0.0.1:80 for an HTTP probe on port 80. The text was updated successfully, but these errors were encountered: @EmreMARTiN, Thanks for the feedback. Have a question about this project? 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.
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