At present, the AspNetWindowsAuthentication is not supported in .NET Core. ASP.NET Core does allow for Windows Authentication (through IIS reverse proxy), so it would be great to have support for this in ServiceStack.

I made an attempt at porting it myself, and it kind of works, though I'm sure I'm missing some subtleties on how it works, as I sometimes get "header already set" errors on some requests. In case this never gets picked up, here's a gist of my attempt:

https://gist.github.com/darkonejr/7bcdcf7aea9fee7d21329fd58de5d43d