Access either the Administration Server or the Server Manager and choose the Preferences tab.
From the Server Manager you must first select the server instance from the drop-down list.
Click the Edit Listen Sockets link.
The Edit Listen Sockets page appears.
Click the Listen Socket Id link corresponding to the listen socket you are requiring client authentication for.
The Edit Listen Socket page appears.
To require client authenticate for the listen socket, select Required from the Client Authentication drop-down list.
From the Server Manager, click Apply, and then Restart for changes to take effect.
Currently, there is a single certificate trust database per web server instance. All the secure virtual servers running under that server instance share the same list of trusted client CAs. If two virtual servers require different trusted CAs, then these virtual servers should be run in different server instances with separate trust databases.