Security app wrapper?

Hi all.

Is there any commercial systems that you can wrap a web forms app in and host securely on the internet?

I have a CRM intranet  system that's not on the internet and we want to put it on the internet. I dont know a great deal about adding security for internet so wondered if there is a way to wrap  an existing app. To host it securely. 

E.g. you'd log into it and it would the  give you access to the program under it.

Tia

Dave