ssh_config(5) on macOS
The text 7e0acd55c3bd, as Mac OS X 10.5.8, Mac OS X 10.5.7, Mac OS X 10.5.6, Mac OS X 10.5.5 shipped it.
OpenSSH SSH client configuration files
The text 7e0acd55c3bd, as Mac OS X 10.5.8, Mac OS X 10.5.7, Mac OS X 10.5.6, Mac OS X 10.5.5 shipped it.
OpenSSH SSH client configuration files