Cisco IOS Software-based SSG services provide subscriber authentication, service selection, service connection, and accounting capabilities in conjunction with the Cisco CNS SESM, a software toolkit that resides on a Windows, UNIX, or Linux server. Integrated services routers with SSG services can support up to 1000 users and can provide an ideal system for large, multiservice provider hotspots (for example, airports) and distributed public WLAN network deployments:
* SSG can authenticate and authorize subscribers to access public (or enterprise) WLAN services.
* In conjunction with a billing server, SSG can provide per-subscriber, per-service billing in both post- and prepaid billing modes.
* In conjunction with SESM, SSG can provide a Web portal for subscriber authentication and self-subscription, as well as service provider branding.
* SSG provides open-garden and walled-garden services for controlled access of information to subscribers.
Check the following link for configuring SSG :
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008044c352.html