Port forwarding is the legacy technology for supporting Winsock 2, TCP-based applications over a clientless SSL VPN connection. With port forwarding, remote users may need administrator privileges to connect the local application to the local port.As an administrator configuring port forwarding on the security appliance, you must specify the port the application uses; as an administrator configuring smart tunnel access, you must specify the name of the executable file.
http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/webvpn.html#wp1291474
