t_enabling_sslvpn
Go to Network > User VPN > SSL VPN > General.
Check the Enable SSL VPN check box.
See also:
Installing the SSL VPN Client
Secure Socket Layer Virtual Private Network
Configuring General SSL VPN Server Settings
Configuring Local Networks for SSL VPN
Configuring Virtual IP Address Pools for SSL VPN
Configuring Advanced Settings for SSL VPN
Viewing SSL VPN Clients
Viewing SSL VPN Logs
Troubleshooting SSL VPN