Set default Domain name for authentication when using VPN

Question

Hello

 

I've setup an MVC C# wep application with Windows Authentication using MS Visual Studio 2013

authentication mode="Windows" 

 

It works great, when the user is on the corporate network (CN); when the user goes to the web app in IE or Chrome, the authentication is automatic and seamless. If the user uses Firefox, a popup requests the user's network credentials, which is fine... as long I don't have to manage usernames and passwords anymore.

By the way the popup is an integrated part of the browser reacting to the reponse from the web app, I do not control this. 

 

The problem happens when the user tries to connect to the web app from home through the use of a secure VPN. Once authenticated, when the user opens up IE to go the web app, the authentication is not "automatic and seamless" anymore...a popup requests the user's network credentials...but that is not all, the user must prefix his username with the corporate network (CN) else the active directory will not recognize him (cn\jorion) because I presumes the local domain name is used and different from the corporate network (CN)

 

Is there a way I can set it so the user does not have to prefix his username with the corporate domain name (cn) for authentication when using VPN?