Skip to main content

NuGet - Package Source Mappings

With NuGet 6.0, a new feature Package Source Mapping was introduced. Goal of this feature is to help improve security by safeguarding your software supply chain.

What is Package Source Mapping?

If I want to explain what Package Source Mapping is, I should start by explaining the concept of a Package Source. In NuGet a Package Source is the source where nuget searches for packages. This can a public source(like nuget.org) and/or a private source(like Azure Artifacts or a local disk).

You can add a package source by executing the following command:

dotnet nuget add source <source> –n MySource

It is possible to define multiple sources. By default when multiple sources are defined nuget will scan all configured package sources to find and restore a specific package. This introduces a risk as you are not sure where a specific package is coming from.

A risk that can be mitigated by using Package Source Mapping(PCM). PCM allows to centrally declare which source each package in your solution should restore from in your nuget.config file.

You can configure Package Source Mapping directly in the Visual Studio IDE.  For each mapping you need to specify a pattern and one or more package sources:


This will update your nuget.config file like this:

Starting from NuGet 6.7 this got improved even further as you can easily see when NuGet packages are (not) mapped to respective package source(s):


More information:

Announcing NuGet 6.7 – Keeping You Secure - The NuGet Blog (microsoft.com)

Package Source Mapping | Microsoft Learn

dotnet nuget add source command - .NET CLI | Microsoft Learn

Popular posts from this blog

DevToys–A swiss army knife for developers

As a developer there are a lot of small tasks you need to do as part of your coding, debugging and testing activities.  DevToys is an offline windows app that tries to help you with these tasks. Instead of using different websites you get a fully offline experience offering help for a large list of tasks. Many tools are available. Here is the current list: Converters JSON <> YAML Timestamp Number Base Cron Parser Encoders / Decoders HTML URL Base64 Text & Image GZip JWT Decoder Formatters JSON SQL XML Generators Hash (MD5, SHA1, SHA256, SHA512) UUID 1 and 4 Lorem Ipsum Checksum Text Escape / Unescape Inspector & Case Converter Regex Tester Text Comparer XML Validator Markdown Preview Graphic Color B

Help! I accidently enabled HSTS–on localhost

I ran into an issue after accidently enabling HSTS for a website on localhost. This was not an issue for the original website that was running in IIS and had a certificate configured. But when I tried to run an Angular app a little bit later on http://localhost:4200 the browser redirected me immediately to https://localhost . Whoops! That was not what I wanted in this case. To fix it, you need to go the network settings of your browser, there are available at: chrome://net-internals/#hsts edge://net-internals/#hsts brave://net-internals/#hsts Enter ‘localhost’ in the domain textbox under the Delete domain security policies section and hit Delete . That should do the trick…

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.