#security

The squiggly letters guarding every signup form are a 1950 thought experiment turned inside out: a human laboring to convince a machine it is not one. The acronym says exactly that, and the words it made you type were quietly put to work.

Before it filtered packets, a firewall was a literal wall — a fire-resistant barrier in buildings from the 1850s, then the iron bulkhead behind a vehicle's engine. The networking sense borrowed the metaphor in the late 1980s and was cemented by Cheswick and Bellovin's work at Bell Labs.

Tatu Ylönen wrote SSH at Helsinki University of Technology in July 1995 after a password-sniffing incident. Thirty years later it is the default remote-access protocol on every Unix-like operating system, including Windows. Almost nothing else in security tooling has lasted as long unchanged.