Find out more about the Microsoft MVP Award Program. If it's not, the certificate is considered invalid, and that will create a Making statements based on opinion; back them up with references or personal experience. To create a custom probe, follow these steps. In this example, you'll use a TLS/SSL certificate for the backend certificate and export its public key to be used as authentication certification. 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. Message: The root certificate of the server certificate used by the backend does not match the trusted root certificate added to the application gateway. Ensure that you add the correct root certificate to whitelist the backend". If the backend server response for the probe request contains the string unauthorized, it will be marked as Healthy. @TravisCragg-MSFT: I have same configuration on different places which were built a while ago and those are perfectly working fine. -verify error:num=19:self signed certificate in certificate chain privacy statement. error. Unfortunately I have to use the v1 for this set-up. Nice article mate! If they aren't, create a new rule to allow the connections. Well occasionally send you account related emails. 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" This article describes the symptoms, cause, and resolution for each of the errors shown. f. Select Save and verify that you can view the backend as Healthy. to your account. What was the resolution? Application Gateway probes can't pass credentials for authentication. Message: Time taken by the backend to respond to application gateway's health probe is more than the timeout threshold in the probe setting. 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. We should get one Linux machine which is in the same subnet/VNET of the backend application and run the following commands. If the backend server doesn't If your certificate is working on browser directly hitting the app and not with AppGW then what is the exact problem? 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. Cause: When you create a custom probe, you can mark a backend server as Healthy by matching a string from the response body. In this article I am going to talk about one most common issue "backend certificate not whitelisted" . I will let you know what I find. 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. It is required for docs.microsoft.com GitHub issue linking. 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. Thanks for contributing an answer to Stack Overflow! This is the exact thing what we do when import .CER file in the HTTP Settings of the Application Gateway. Check whether the server is listening on the port that's configured. If they don't match, change the probe configuration so that it has the correct string value to accept. Content Source:<---> Passing negative parameters to a wolframscript. 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. 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). 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. The text was updated successfully, but these errors were encountered: @EmreMARTiN, Thanks for the feedback. If thats not a desired value, you should create a custom probe and associate it with the HTTP settings. 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 Check the document page that's provided in step 3a to learn more about how to create NSG rules. For example: probe setting. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Your email address will not be published. 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. Configure that certificate on your backend server. How to Change Network Location to Private, Public, or Domain in Windows 11? To do end to end TLS, Application Gateway requires the backend instances to be allowed by uploading authentication/trusted root certificates. A pfx certificate has also been added. 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. Check whether the host name path is accessible on the backend server. If you do not have a support plan, please let me know. Allow the backend on the Application Gateway by uploading the root certificate of the server certificate used by the backend. I will clean-up some of my older comments to keep it generic to all since the issue has been identified. To find out the reason, check OpenSSL diagnostics for the message associated with error code {errorCode}. 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. 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. Can you please add reference to relevant Microsoft Docs page you are following? Microsoft Word Multiple Choice Questions & Answers, Excel Multiple Choice Questions & Answers, Different Ways to Change Power Button Action 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. Make sure https probe is configured correctly as well. The section in blue contains the information that is uploaded to application gateway. 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/ Well occasionally send you account related emails. To do that, follow these steps: Message: The validity of the backend certificate could not be verified. c. Check to see if there are any default routes (0.0.0.0/0) with the next hop not set as Internet. The chain looks ok to me. Have done s_client -connect backend_ip:443 -servername backend_url -showcerts and found that Root CA is missing. The gateway listener is configured to accept HTTPS connections. 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). Thanks. 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. xcolor: How to get the complementary color. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. 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. applications. There is certificate with private key as PFX on listenner settings. 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". If Internet and private traffic are going through an Azure Firewall hosted in a secured Virtual hub (using Azure Virtual WAN Hub): a. thank you for sharing it . You should remove the exported trusted root you added in the App Gateway. This causes SSL/TLS negoatiation failure and AppGW marks the backend as unhealthy because it is not able to initiate the probe. Does a password policy with a restriction of repeated characters increase security? 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. 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. OpenSSL> s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts respond within the configured period (the timeout value), it's marked as Unhealthy until it starts responding within the configured timeout period again. You signed in with another tab or window. I had to add a directive in the webserver conf file to enable presentation of the full trust chain. Most of the browsers are thick clients , so it may work in the new browsers but PRODUCTs like Application Gateway will not be able to trust the cert unless the backend sends the complete chain. 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. 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. Version Independent ID: <---> certificate. We have not faced any issues with HTTP sites but we are facing issues with end-to-end SSL. I did not find this error message listed here https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting. 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. Posted in Azure Tagged 502webserver, Azure, azure502, azureapplicationgateway, azurecertificate, azurewaf, backend certificate not whitelisted Post navigation Azure Cyber Security: Protect & Secure Your Cloud Infrastructure 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 To learn more visit - https://aka.ms/UnknownBackendHealth. Sign in to the machine where your application is hosted. OpenSSL s_client -connect 10.0.0.4:443 -servername www.example.com -showcerts. In Azure docs, it is clearly documented that you dont have import Auth certificate in HTTP settings of the backend if your backend application has Global trusted certificate. During SSL negotiation , Client sends "Client Hello" and Server Responds with "Server Hello" with its Certificate to the Client. "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. Or, you can use Azure PowerShell, CLI, or REST API. We are in the 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." For File name, name the certificate file. Message: The Common Name (CN) of the backend certificate doesn't match the host header of the 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. The v2 SKU is not an option at the moment due to lack of UDR support. Something that you will see missing is microsft docs is having a default site binding to a SSL certificate without the SNI enabled. 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. here is the sample command you need to run, from the machine that can connect to the backend server/application. I am currently experimenting with different ways to add the backend pools and heath probes to find a working configuration. To learn more visit https://aka.ms/authcertificatemismatch" I have some questions in regards to application gateway and need help with the same : When i check health probe details are following: During SSL negotiation , Client sends "Client Hello" and Server Responds with "Server Hello" with its Certificate to the Client. To increase the timeout value, follow these steps: Message: Application Gateway could not create a probe for this backend. Enter any timeout value that's greater than the application response time, in seconds. @EmreMARTiN , you mentioned your backend certificate is from "Digicert" which is already a well-known trusted CA. Follow steps 1a and 1b to determine your subnet. The issue was on certificate. b. Cause: Application Gateway resolves the DNS entries for the backend pool at time of startup and doesn't update them dynamically while running. You can add this to the application gateway to allow your backend servers for end to end TLS encryption. 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. 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. https://docs.microsoft.com/en-us/azure/application-gateway/application-gateway-end-to-end-ssl-powershell, Azure Cyber Security: Protect & Secure Your Cloud Infrastructure, Send Text & WhatsApp Messages for Azure VM Status with Azure Automation, Migrate SOAR Use Cases from Splunk to Microsoft Sentinel, Azure Defender and Azure Sentinel Alerts Bi-Directional Sync. Was the error "exactly" the same before you explicitly added the exported root rather than relying on "Digicert" as known authority? 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. Best practices and the latest news on Microsoft FastTrack, The employee experience platform to help people thrive at work, Expand your Azure partner-to-partner network, Bringing IT Pros together through In-Person & Virtual events. . Learn how your comment data is processed. If you're using a default probe, the host name will be set as 127.0.0.1. 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. Have raise case with Microsoft as unable to resolve that myself. Azure Application Gateway: 502 error due to backend certificate not whitelisted in the AppGW, Troubleshoot backend health issues in Azure Application Gateway | Microsoft Docs. 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. Sub-service: <---> Message: The backend health status could not be retrieved. The output should show the full certificate chain of trust, importantly, the root certificate which is the one appgw requires. Your email address will not be published. or is that all the backend pools has to serve the request for one application ? (Ep. Next hop: Internet. You signed in with another tab or window. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? Ended up swapping to App Gateway V2 instead using the Trusted CA cert option on the backend http settings. -> it has been taken from application servers by exporting as documented on Microsoft docs for WAF v2. If you see an Unhealthy or Degraded state, contact support. site bindings in IIS, server block in NGINX and virtual host in Apache. security issue in which Application Gateway marks the backend server as Unhealthy. Is there such a thing as "right to be heard" by the authorities? This will take some time to track down, fix, and the docs will need to be updated with limitations & best practices. If the port mentioned is not the desired port, enter the correct port number for Application Gateway to connect to the backend server. Most of the best practice documentation involves the V2 SKU and not the V1. Error message shown - Backend server certificate is not whitelisted with Application Gateway. 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 Document Details 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. You'll see the Certificate Export Wizard. 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. Current date is not within the "Valid from" and "Valid to" date range on the certificate. Change the host name or path parameter to an accessible value. By default, Azure Application Gateway probes backend servers to check their health status and to check whether they're ready to serve requests. Check the backend server's health and whether the services are running. When we check the certificate with the openssl there were following errors: Set the destination port as anything, and verify the connectivity. Once the public key has been exported, open the file. For the v1 SKU, authentication certificates are required, but for the v2 SKU trusted root certificates are required to allow the certificates. As described earlier, the default probe will be to
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