OpenSSG is an implementation of the Cisco Service Selection Gateway, which is available on IOS devices with the required feature image. It uses libipq for user-space packet inspection. Traffic flows of unauthenticated users are redirected to a SESM (Subscriber Edge Service Manager), where they are authenticated by whatever means (an HTTP server with a database backend, or a telnet server). Upon authentication, the user is authenticated with a certain IP and this is sent to the SSG server.
|Operating Systems||POSIX Linux|