This uses processing to see if you're currently connected to the internet.

very expensive network connection checker.pde

/* Very expensive network connection checker
  Steve Lambert 2017-04-26
  */

void setup() {
  size(250,250);
  smooth();

} // end setup


void draw() {

  if (frameCount % 100 == 0){ // every 100th frame do this...
  
  // pull lines of text from google's webpage into a string:
  String[] lines = loadStrings("http://google.com"); 

  // Now, check to see if anything comes back. If nothing comes
  // back, it returns "null". If we don't check for that, it 
  // will cause an error and the program will crash. So we test
  // for null, which will tell us if we're connected at all.
  
  if (lines == null){
    println("congratulations, you're off the internet");
  } else {
  //println("there are " + lines.length + " lines");
  println("Hi, I see you're on the internet");
  }
} 


} // end draw