How to tell if your internet is up in Linux?

When on a local net or using wifi (that's just about everybody), you really need a way to tell if the "internet" is up or not.  Of course the network applet tells you the wifi or network is up, that is not what you need to know.  You need to know if the internet connection is up.  Here's a cool Gnome panel applet that does just that - it's just not installed on Hardy (Ubuntu 8.04) by default.

Link Monitor Applet is a GNOME Panel Applet displaying the round-trip time to a set of hosts in a bar graph.

Link Monitor Applet features include:

• A line graph able to display up to one week of round-trip time data
• Country flags and names
• Full ICMP and ICMPv6 support
• HIG 2.0 compliance

Link Monitor Applet is free software, released under the terms of the GNU General Public License.

sudo apt-get install link-monitor-applet

After  install with the command above, add the applet to gnome panel.  Add the OpenDNS host 208.67.222.222 and Delay to 10 seconds, Graphs scale to 3 seconds, and Tooltip to 5 minutes.  That should get you started.  Now hover the mouse over the Link Monitor Applet and you can tell if you are up or down and for how long it's been down, etc.  Very nice tool!

Even the Windows network tool can't always tell if you are online:(  With Linux and this applet, you will always know if your internet connection is up and it's displayed in a nice little graph.