I have honestly never seen that message. It seems like it would be a rare situation that you would see it though. Still. Interesting looking at the rundown and the code logic behind it. Archive: https://archive.today/XpFx8 From the post: >>Once my holidays had passed, I found myself reluctantly reemerging into the world of the living. I powered on a corporate laptop, scared to check on my email inbox. However, before turning on the browser, obviously, I had to run a ping. Debugging the network is a mandatory first step after a boot, right? As expected, the network was perfectly healthy but what caught me off guard was this message: I was not expecting ping to take countermeasures that early on in a day. Gosh, I wasn't expecting any countermeasures that Monday! Once I got over the initial confusion, I took a deep breath and collected my thoughts. You don't have to be Sherlock Holmes to figure out what has happened. I'm really fast - I started ping before the system NTP daemon synchronized the time. In my case, the computer clock was rolled backward, confusing ping.