Methods and systems authenticate and authorize an extranet client to a secure intranet business application with a perimeter network topology, where connections to the secure intranet business application from outside the secure intranet are not permitted. A perimeter network proxy is authenticated within the secure intranet. The perimeter network proxy corresponds to an authenticated extranet client. If the perimeter network proxy is authenticated, information on an intranet business application client is acquired and used to create a session with the intranet business application. The intranet business application client corresponds to the extranet client, and the extranet client uses the session to submit requests to the intranet business application.