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. 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. Ensure that you add the correct root certificate to whitelist the backend. Is there such a thing as "right to be heard" by the authorities? Thanks for this information. 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. Select the root certificate and then select, In the Certificate properties, select the, Verify the CN of the certificate from the details and enter the same in the host name field of the custom probe or in the HTTP settings (if. 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". Do not edit this section. Export trusted root certificate (for v2 SKU): 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. 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. 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. Making statements based on opinion; back them up with references or personal experience. Were you able to reproduce this scenario and check? 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. 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. 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. 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. backend server, it waits for a response from the backend server for a configured period. Configure that certificate on your backend server. If the backend server response for the probe request contains the string unauthorized, it will be marked as Healthy. . 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 Service unavailable. site bindings in IIS, server block in NGINX and virtual host in Apache. The default probe request is sent in the format of ://127.0.0.1:. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Either allow "HTTP 401" in a probe status code match or probe to a path where the serverdoesn't require authentication. 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. 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. 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? Ended up swapping to App Gateway V2 instead using the Trusted CA cert option on the backend http settings. On the Export File Format page, select Base-64 encoded X.509 (.CER)., and then click Next. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. After you've figured out the time taken for the application to respond, select the. Backend Health page on the Azure portal. Thanks in advance. to your account. Below is what happens during SSL negotiation when you have single chain cert and root in the AppGW. If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? 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. Azure Tip #9 Application Gateway Backend Certificate not whitelisted Error, Azure DevOps Fix for Access to path \SourceMapping.json is denied. Connect and share knowledge within a single location that is structured and easy to search. Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action in Windows 11. multiple chain certificate and if your backend application/server sends only the leaf the certificate , AppGW . To create a custom probe, follow these steps. If you're using a default probe, the host name will be set as 127.0.0.1. Do not edit this section. 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. Solution: Follow these steps to export and upload the trusted root certificate to Application Gateway. The exported certificate looks similar to this: If you open the exported certificate using Notepad, you see something similar to this example. 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. 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 . here is what happens in in Multiple chain certificate. You must be a registered user to add a comment. For example: c. If it's not listening on the configured port, check your web server settings. Thanks. error. Sign in 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. The custom DNS server is configured on a virtual network that can't resolve public domain names. 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. For new setup, we have noticed that app gateway back-end becomes unhealthy. Message: The root certificate of the server certificate used by the backend doesn't match the trusted root certificate added to the application gateway. Azure Tip #11 Get Reports of ARM Deployments in Your Subscription. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. Expected:{HTTPStatusCode0} Received:{HTTPStatusCode1}. Configure that certificate on your backend server. Ensure that you add the correct root certificate to whitelist the backend". Have done s_client -connect backend_ip:443 -servername backend_url -showcerts and found that Root CA is missing. 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. Which was the first Sci-Fi story to predict obnoxious "robo calls"? Message: The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. This can create problems when uploaded the text from this certificate to Azure. If the port mentioned is not the desired port, enter the correct port number for Application Gateway to connect to the backend server. For File to Export, Browse to the location to which you want to export the certificate. Azure Application Gateway: 502 error due to backend certificate not whitelisted in the AppGW, Troubleshoot backend health issues in Azure Application Gateway | Microsoft Docs. Content Source:<---> The reason why I try to use CA cert is that I manage all the resource in terraform, with a single CA cert, it is better to automate the process. Solution: If you receive this error, follow these steps: Check whether you can connect to the backend server on the port mentioned in the HTTP settings by using a browser or PowerShell. Hi @TravisCragg-MSFT : Were you able to check this? Is "I didn't think it was serious" usually a good defence against "duty to rescue"? 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. The text was updated successfully, but these errors were encountered: @EmreMARTiN, Thanks for the feedback. Opinions, tips, and news orbiting Microsoft. AppGW is a PaaS instance , by default you wont get access to the Applicaiton Gateway. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Azure Application Gateway 502 Web Server Backend Certificate not whitelisted. I will now proceed to close this github issue here since this repo is for MS Docs specifically. To resolve the issue, follow these steps. Ensure that you add the correct root certificate to whitelist the backend". Access forbidden. If it's a self-signed certificate, you must generate a valid certificate and upload the root certificate to the Application Gateway HTTP settings. Currently we are seeing issues with app gateway backend going unhealthy due to backend auth cert. 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. 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. 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. 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. Message: Body of the backend's HTTP response did not match the @TravisCragg-MSFT : Did you find out anything? How to Restart Windows Explorer Process in Windows 11? Passing negative parameters to a wolframscript. If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? A pfx certificate has also been added. -Verify return code: 19 (self signed certificate in certificate chain). We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. 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. By clicking Sign up for GitHub, you agree to our terms of service and 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. Ensure that you add the correct root certificate to whitelist the backend. 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 Document Details 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. To Answer we need to understand what happens in any SSL/TLS negotiation. On the Details tab, select the Copy to File option and save the file in the Base-64 encoded X.509 (.CER) format. If you do not have a support plan, please let me know. Note that this .CER file must match the certificate (PFX) deployed at the backend application. We initially faced an issue with the certificate on the backend server which has since been sorted out by MS Support. rev2023.5.1.43405. here is the sample command you need to run, from the machine that can connect to the backend server/application. During SSL negotiation , Client sends Client Hello and Server Responds with Server Hello with its Certificate to the Client. An authentication certificate is required to allow backend instances in Application Gateway v1 SKU. Asking for help, clarification, or responding to other answers. An existing backend certificate is required to generate the authentication certificates or trusted root certificates required for allowing backend instances with Application Gateway. @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. "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. Change). 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. Your certificate is successfully exported. The probe requests for Application Gateway use the HTTP GET method. b. 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. This configuration further secures end-to-end communication. This approach is useful in situations where the backend website needs authentication. Parabolic, suborbital and ballistic trajectories all follow elliptic paths. Check whether the host name path is accessible on the backend server. Failing endpoint is missing root CA as working one has it. or from external over WAF ? 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. If you've already registered, sign in. 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. 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. If you don't mind can you please post the summary of the root here to help people who might face similar issue. Check whether the backend server requires authentication. 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. If there's a custom DNS server configured on the virtual network, verify that the servers can resolve public domains. 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. Visual Studio Code How to Change Theme ? 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. i have configured a Azure Application gateway (v2) and there is one backend servers. You must have a custom probe to change the timeout value. Have a question about this project? 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. 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. Now Clients will check the Server certificate and confirm if the certificate is issued by Trusted root or not. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. When i check health probe details are following: 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. I will clean-up some of my older comments to keep it generic to all since the issue has been identified. Message: The Common Name (CN) of the backend certificate doesn't match the host header of the probe. 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? Select the root certificate and then select View Certificate. The certificate that has been uploaded to Application Gateway HTTP settings must match the root certificate of the backend server certificate. 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. 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 ? d. If an NSG is configured, search for that NSG resource on the Search tab or under All resources. To restart Application Gateway, you need to. 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.
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