How do you find the users name/Identity in C#

c# .net windows-authentication identity
minty picture minty · Dec 9, 2008 · Viewed 33k times · Source

I need to programatically find the users name using C#. Specifically, I want to get the system/network user attached to the current process. I'm writing a web application that uses windows integrated security.

Answer

Marc Gravell picture Marc Gravell · Dec 9, 2008

The abstracted view of identity is often the IPrincipal/IIdentity:

IPrincipal principal = Thread.CurrentPrincipal;
IIdentity identity = principal == null ? null : principal.Identity;
string name = identity == null ? "" : identity.Name;

This allows the same code to work in many different models (winform, asp.net, wcf, etc) - but it relies on the identity being set in advance (since it is application-defined). For example, in a winform you might use the current user's windows identity:

Thread.CurrentPrincipal = new WindowsPrincipal(WindowsIdentity.GetCurrent());

However, the principal can also be completely bespoke - it doesn't necessarily relate to windows accounts etc. Another app might use a login screen to allow arbitrary users to log on:

string userName = "Fred"; // todo
string[] roles = { "User", "Admin" }; // todo
Thread.CurrentPrincipal = new GenericPrincipal(new GenericIdentity(userName), roles);

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