Automatically build and deploy .NET core 3 console application as a Windows service

In this post, I want to share an example of using Azure Devops to automatically build and deploy a .NET console application as a windows service to run on a Windows VM.

How to resolve “An exception was forcibly closed by the remote host” in a .NET app running on an azure VM behind a load balancer.

I get the error “An exception was forcibly closed by the remote host” occasionally at work. This is an I.O exception and happens when a HTTP request fails to reach the destination host. To troubleshoot, I often ping or tracert the destination IP/URL, and the error usually comes down to the firewall restricting the connection, and goes away once we have updated the firewall to handle the connection. However, another instance when I get this error is when my app that runs on an azure VM of a load balancer tries to send a request to another app which has a DNS that points to the same load balancer.

How to retrieve connection strings in azure key vault from ASP.NET using configuration builders, XML transformation and azure devops.

Configuration builders are mechanisms to retrieve connection strings from external sources. Using configuration builders, you may not have to do much codings besides installing packages and providing XML configurations for connecting to popular sources. In this post, I share with you my experience in using configuration builders for .NET to securely retrieve connection strings from an azure key vault. I’ll go over the setup and share some of the issues I face while integrating my app with azure key vault.

Obtain access token via authorization code grant with PKCE in angular using oidc-client-js and Microsoft Identity Platform.

Recently, I learned about why implicit flow is not secure because of exposing the access token in the browser. Authorization code grant with PKCE is more secure and should be preferred over implicit flow for protecting a public application which cannot keep the client secret secure. The good new is if you already use oidc-client-js and get tokens from azure ad via implicit flow, the changes you have to make to use authorization code flow with PKCE are minimal. In this post, I show what you need to change to use authorization code grant with PKCE.

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Securely log to blob storage using NLog with connection string in key vault.

If you do a simple google search on how to log to blob storage using NLog, you can find examples from the project page as well as posts from other developers. However, in most of the examples I have found, the connection string for the blob storage are directly embedded in the nlog.config file, which is not ideal. In this post, I show you another example of using NLog to log to azure blob storage, with the connection string coming from an azure key vault.

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How to authenticate user against Azure ADB2C from Angular app using oidc-client-js.

In this post, I show you how to authenticate your user against azure adb2c to obtain an id and access token. Specifically, we’ll discuss the following:

• Create azure adb2c directory
• Register applications in b2c tenant.
• Define scopes and setup permissions.
• Setup sign up and sign in user flow.
• Authentication service.
• Response to authentication events in component.

Please checkout the latest codes for this post here.

Also, check out the follow-up posts relating to using oidc-client-js to interact with Azure ADB2C:

• Integrate Azure ADB2C edit-profile user flow.
• Integrate Azure ADB2C reset-password user flow.

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Implement OAuth2 Client-Credentials flow with Azure AD and Microsoft Identity Platform.

OAuth2 Client Credentials flow is a protocol to allow secure communication between two web APIs. Specifically, the protocol specifies the flow of obtaining authorization for a client to access protected endpoints of a resource server with no user interaction involved. With Microsoft Identity Platform, Azure portal, Microsoft Authentication Library (MSAL), and .NET core security middleware, you can implement the OAuth2 client credentials flow without much difficulty. In this post, I go over how to leverage those technologies to protect your ASP.NET core web APIs.

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Connect to azure key vault from an ASP.NET core app using azure managed identity

Of the three different ways to access an azure key vault from an ASP.NET core application, if your app runs on an azure resource, the best option is using azure managed identities for simplicity and the highest security. In this post, I go over how I configure the application and azure sides to leverage azure managed identities when accessing the key vault.

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Configure OAuth2 implicit flow for Swagger UI

In this post, I share some example codes of how to enable OAuth2 implicit flow within Swagger UI to obtain an access token from Microsoft Identity Framework (v2.0 endpoint).

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Pass user’s identity and authorization from a client application to a web API to another web API using OAuth 2.0 On-Behalf-Of flow.

A few months ago, I gave an overview of the libraries I use to implement OpenID Connect implicit flow in an angular app, and On-Behalf-Of (OBO) flow in ASP.NET core backend APIs. You can checkout this post for more info. In that post, I talk about the security flow from the angular app to the downstream APIs. The angular app communicates only with a single backend API which acts as a gateway that forwards the requests from to other downstream APIs.

In this post, I go over the details of obtaining an access token via the OBO flow to call protected endpoints from a web API (which I refer to as the gateway in this post) to another web API .

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