A system and method for authenticating a legacy service using internet technology is disclosed. An authentication module is associated with the legacy server. Service requests from a user of the legacy server are passed to the authentication module. The authentication module generates a service request for a web server, requesting access to a protected page from the web server, and transmits the user's credentials to the web server. The web server attempts to access the protected server, which causes the web server to access a network-based authentication service to determine whether the user's credentials qualify for access to the protected page. The web server transmits a message back to the authentication module, which determines whether the user's credentials qualify for access the legacy server based on the message from the web server.