In one embodiment, an authentication protocol used in a network security service is performed over non-secure connection, such as HTTP. A router subscribing to the service may send a service request for information about a URL to a server computer providing the service. The service request may be included in a first data set posted by the router to the server computer. The first data set may be described by an HTML form and include an encrypted device authenticator used by the server computer to validate the router. The first data set may further include a server authentication code. In responding to the service request, the server computer returns the server authentication code to the router along with information about the URL. The response may be in a second data set, such as an XML document sent by the server computer to the router over an HTTP connection.