title: creating externalregistration page in Identityserver3
body: <p>I have identityserver3 service running great, the service is doing custom authentication and using angular pages to redirect for permissions, index, login and logoff pages as in IdentityServer3 example - CustomUser.</p>
  
  <p>Now, I need to add external providers (say Google). I am not sure I completely understand how to redirect to "someexternalregistration" after google successfully authenticate to a page that would ask the user for userid of our system that will be associated with google login on all future calls.</p>
  
  <p>so say the url for identity service is <a href="https://server/identity/login" rel="nofollow">https://server/identity/login</a>, <a href="https://server/identity/permissions" rel="nofollow">https://server/identity/permissions</a> etc.....</p>
  
  <p>How do I map <a href="https://server/identity/someexternalregistration" rel="nofollow">https://server/identity/someexternalregistration</a> to html page?</p>
  
  <p>Thank you
  Mark</p>