SSH clients can be configured with environment variables,
command-line options, and keywords in configuration files.
Command-line options have the highest precedence, followed by your
local client configuration file, and finally the global client
Client configuration files consist of sections, and multiple sections
can apply to a single invocation. If the same keyword is set multiple
times, the earliest value is the winner.
When experimenting with client configuration, remember verbose mode.
If you experience unusual SSH behavior, your first instinct should be
to add the -v option and run the client again,
watching the debug output for clues.