~/.bash_completion.d/

bash-completion-ssh.sh

# http://fahdshariff.blogspot.co.za/2011/04/writing-your-own-bash-completion.html
# https://unix.stackexchange.com/a/181603/111459
_ssh() {
  local cur prev opts
  COMPREPLY=()
  cur="${COMP_WORDS[COMP_CWORD]}"
  prev="${COMP_WORDS[COMP_CWORD-1]}"
  opts=$(grep --no-messages '^Host' ~/.ssh/config ~/.ssh/config.d/* | grep -v '[?*]' | cut -d ' ' -f 2-)

  COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
  return 0
}
complete -F _ssh ssh