Question: News reports tell of major DDoS against a famous company. You receive a letter from your ISP saying that your home is sending malicious Linux-sourced traffic. But you don't own a Linux computer, in fact you don't own any computer. Your home electronics are limited to a smart TV with a Blu-ray player and a DVR or Digital Video Recorder. What has happened?
A: Nothing, your ISP is wrong
Blu-ray players and many smart TVs and DVRs contain small single-board Linux systems, running a very old version of the operating system with no way to patch it. At least one of them is part of a botnet like Mirai.