How can i go about programaticaly getting the IP address of my network as seen from the Internet? Its obviously a property that my router has access to when it connects to the ISP. Is there any way to get this info from a router using a standard protocol. My only other option is to either find a WS which returns my IP address (suprisingly difficult to do), or just go to something like whatismyip.com and strip out all the HTML (very dirty and susceptable to change). Is there any other way???
Answer
Don't scrape whatismyip.com, see here for how you can call their API which just returns your address.
If you don't use this, you have to write something like it yourself, i.e. a host beyond your router which can report back your apparent address.
Note that webserver might not see your real WAN IP address because:
your ISP might be transparently proxying HTTP traffic, and the server would see the IP of the proxy. In that case, you'd typically need to look for and parse a X-Forwarded-For header.
or, as Olaf noted, there may be another NAT router between you and the wide open Internet, in other words, the WAN address of your router is on a private network. The best you'd get from a service like whatismyip.com is the IP of the outermost NAT router.