Can I use Service Principal to authenticate an application that is not hosted in Azure using role-based access control? - azure

I've created an event hub that I want to call from an app hosted outside of Azure. Can I create a service principal in AAD and use it for authentication of the non-Azure hosted application?

Yes, it doesnt matter if the application is hosted in Azure or not, service principal is used to auth, it doesnt check where you are hosting the app.
But i dont think you can use service principal to talk to event hub, you will need to use connection string

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Provide App service security in Azure solutions

I have a click once windows application which already has authentication n Authorization built in. Earlier i used to deploy it on physical server n share the location with users so that they can install it n use it. But now we have decided to deploy it on azure PAAS service (App service ). But currently url is geting access by anyone which i want to restrict. Currently my organization AD is not synced with Azure AD. So not able to use Azure AD for authentication.
Kindly provide some better solutions other than restricting users based on IP.
If it's a file download you can put it on Azure Blob storage for download and generate short-time SAS tokens.
While IP address restrictions and Azure AD authentication would be one-efficient approach for your scenario. Since you do not want to go that route (due to environment limitations), If you wish you could authenticate users with the specified provider (Microsoft Account, Facebook, Google, Twitter or Any OpenID Connect provider). App Service provides built-in authentication and authorization support, so you can sign in users and access data by writing minimal or no code.
App Service uses federated identity, in which a third-party identity provider manages the user identities and authentication flow for you. You can also use multiple sign-in providers.
So the simple process could be:
The option is Log in with . App Service redirects all anonymous requests to /.auth/login/<provider> for the provider you choose. If the anonymous request comes from a native mobile app, the returned response is an HTTP 401 Unauthorized.
Kindly checkout step-step instructions on the process/workflow:
Configure your App Service or Azure Functions app to use Microsoft Account login
If your WebApp is on VNet, you can have service endpoints enabled for Microsoft.Web, through access restrictions.
See- Advanced usage of authentication and authorization in Azure App Service

Is it possible to connect to on-prem API through Azure AD Application Proxy without interactive user login?

I'd like to connect to an On-Prem API from an external cloud service using the Azure AD Application Proxy. I can connect and use the API by logging in with my Azure AD User in a browser, but would like a code-based-like login to use from my external service.
I've been digging through various articles the last couple of days, and it seems not possible without an Azure AD User interactive login. I am able to create an AD user for this service only if needed, but handling the interactive login from code or even through Postman seems troublesome.
Can someone point me in the right direction to solve this cloud-service to on-prem app solution? (unfortunately, I can't move the on-prem app to Azure).
EDIT: I'll be looking at using the pass-through option in the App registration, which means i need to handle the authentication and security in my API.
Perhaps you could consider using an on-premises data gateway instead, but it depends on where your external cloud service is hosted.
https://learn.microsoft.com/en-us/azure/logic-apps/logic-apps-gateway-install
Essentially, if your external cloud service is completely outside your environment and your control, the data gateway can still be used, then you can expose a Logic App as a facade that can integrate with the on-premises data gateway. The external cloud service can then call the logic app to trigger the request, which can be secured by other means e.g. SAS key.

Is it possible to have Azure App Registration in one tenant and App Services in another

Does anyone know if it's possible to create a App Registration in one tenant and then use that registration in another tenant within App Services?
Regards, Oskar
In general yes it is. If you create an app registration, you might define the URL of the App Service in its reply URLs.
Then you can define on the App Service that it should use authentication with a given AAD tenant.
After all you can use AAD authentication anywhere, on an app hosted in AWS, the Google cloud or an on-prem server.
Of course the Authentication/Authorization feature of App Service is only available there, but that doesn't stop you from configuring authentication within your app.
Managed Identity is a feature that only works within the tenant connected to the subscription though.

Access on Premise resources using Azure AD Application proxy

we have configured azure active directory pass-through authentication . Need to access on premise resources from the azure deployed application. can we do this by configuring application proxy?. so that on premise application authenticated with azure AD. so the communication between azure application and on premise application be seamless. Is it possible?
I'm not entirely sure if I understand you correctly but what you want is probably possible by using Azure Hybrid Connections: https://learn.microsoft.com/en-us/azure/app-service/app-service-hybrid-connections
You install the Hybrid Connector on-prem, e.g. on a VM, and then for instance an Azure App Service can access certain resources on-prem.
Or for anything more advanced you might want to look at Azure VPN (or ExpressRoute in the long run).

Make back end APIs only accessible via Azure API management

I have multiple Web APIs deployed in Azure without applying authentication, so anyone has access to internet has the access to the Web APIs.
Now I would like to apply authentications to the Web APIs, instead of implementing the same authentication logic in different Web APIs, I found Azure API gateway (API management) is a potential solution.
With Azure API management documentation, I learned I can apply policies like validate-jwt to authenticate requests to back end Web APIs. However, endpoints of the back end Web APIs are still available to users.
So, how should I hide them? Must I define a sub network or does Azure API management have a feature for this?
Recently I also had this same problem. Finally I found the solution by using 'IP Restrictions' function. See the following steps:
1) Go to your API management Overview page in Azure portal, copy the VIP.
2) In your Web APP > Networking
3) Paste in your VIP
Microsoft's Solution: How to secure back-end services using client certificate authentication in Azure API Management
Using this approach, any attempt to access a back-end service without the required certificate will result in a 403 - Forbidden response.
You can use a self-signed certificate as opposed to using a trusted CA signed certificate ($$). I chose to implement an Azure Key Vault where I generated a new certificate, downloaded it as a *.PFX file, and uploaded it into my API Management instance as described in the article.
Here is an answer from #PramodValavala-MSFT
https://github.com/MicrosoftDocs/azure-docs/issues/26312#issuecomment-470105156
Here are options:
IP restrictions (as described by #redman)
Function keys
Authentication/Authorization for Functions
Managed Identity for APIM
p.s. in my case I want with IP restrictions since it allows to keep all of the auth on the API Management Gateway.
Or you could use:
Basic auth
Mutual certificate auth
VPN
to secure Azure API Management service communication with your backend service.
Look into setting up TLS on Azure API Management so that all connections to your backend API must come through the API proxy.
Azure API management cannot modify your backend service. It's role is limited to being a proxy.
You will have to apply authentications to each Web API or configure your firewall to accept requests only from Azure APIM.
Is your backend app an Azure Function app or an App Service app?
If so, Managed Identity may be the simplest way to restrict access. No need to store client secrets/certificates in the API Management + not as flaky as IP whitelisting method.
Create an Azure Active Directory Application for the Function App.
Enable Authentication/Authorization module on the Function App and reference the AAD app from step 1.
Enable a Managed Identity on the APIM instance.
Add a <authentication-managed-identity> policy to the APIM and reference the AAD app from step 1.
I've blogged about this approach in more detail in Restrict Azure Functions to API Management with Terraform
Reference:
Use managed identities in Azure API Management
Configure your App Service or Azure Functions app to use Azure AD login

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