You probably are looking into Network and Sharing Center on windows, which says if you have internet or not, as shown bellow in the screen. But this is not always a reliable method. For example , on my college network, some computers say there's no internet, and yet I can surf internet just fine.
heemayl alrady mentioned ping
command which is the basic network testing tool on any system, windows or linux, and it is used in command line; the app for that is cmd
on windows and terminal
on ubuntu or any other linux distro, and macs. If you can ping -c4 google.com
and get response, you have internet.
There's another method, graphical, using gnome-nettool
, which is an app with network utilities all put together into graphical interface. Idea is the same, ping utility to test if you have response from internet; there's also traceroute, which will show if you can go past your router ip address to the internet or not.
Another way is through Unity Lenses and Scopes. Remember how when you type in dash when you search for some files, you get suggestions from amazon? well, that means those suggestions come from internet, right ? Personally, I have those disabled, so can't elaborate much on this.
But really, command line tools are far more reliable and much better and many linux users will strongly recommend you use those