Security researchers have been warning about these internet-of-things botnets since at least the summer. In September, a botnet composed of DVRs and CCTVs took down the blog of Brian Krebs, a prominent cybersecurity journalist. And on October 1, an anonymous developer posted source code online that allowed anyone to string a similar kind of botnet together.

Krebs wrote that releasing that software, called Mirai, “virtually [guaranteed] that the Internet will soon be flooded with attacks from many new botnets powered by insecure routers, IP cameras, digital video recorders and other easily hackable devices.”

The first of those attacks to be successful on a broadly destructive scale transpired on Friday.

“This feels new,” Bruce Schneier, a long-time computer-security researcher, told me by phone on Friday. “There hasn’t been a successful attack like this before.” There have been many unsuccessful ones that may have been larger, he added.