Service Portal Redirect

[Ashish Kathait]

Users are using Portal but not sure about dev or Prod, So I want only few test users to be able to open service portal rest will not. How and which is ideal way to achieve it. 

[Ashish Kathait]

Thanks @ ChiranjeeviR  I am trying the same option at bottom with User Criteria but not working. Will check with Roles check box.