Most IP Update clients and remote authentication services rely on external servers to capture the local WAN IP. If such services are run from within a LAN / localhost and the remote user needs to verify the actual IP dishing out the services, it is best to parse the WAN IP from the local router.

Once such script for the NetGear DG834G WiFi ADSL router is now available at my repo. It does not use any cURL or other fancy libraries and can be run off localhost and CLI. It can be adapted for other routers / gateways that use such realm based authentication.