Comment 7 for bug 911706

I ran into this today. NM hasn't been working so I switched to wicd and was surprised when it broke USC.

To resolve it, my first choice would be to simply attempt to use the network as usual and handle the exceptions if it fails.

However, if the UI needs to be configured differently depending on network state, I'd do a connectivity check like mpt suggested. Simply pinging or tcp connect()ing to ubuntu.com (or maybe the ratings and reviews server) would be sufficient in most cases. If you want to get a little more sophisticated and verify there's no content filter or captive portal in the way, one could instead HTTP GET a known page and verify the contents. But networking in Linux is so wildly variable on different systems that I wouldn't attempt to check any local config.