# File lib/knife-solo/ssh_command.rb, line 104
    def validate_ssh_options!
      if config[:identity_file]
        ui.warn '`--identity-file` is deprecated, please use `--ssh-identity-file`.'
      end
      unless first_cli_arg_is_a_hostname?
        show_usage
        ui.fatal "You must specify [<user>@]<hostname> as the first argument"
        exit 1
      end
      if config[:ssh_user]
        host_descriptor[:user] ||= config[:ssh_user]
      end

      # NOTE: can't rely on default since it won't get called when invoked via knife bootstrap --solo
      if config[:ssh_keepalive_interval] && config[:ssh_keepalive_interval] <= 0
        ui.fatal '`--ssh-keepalive-interval` must be a positive number'
        exit 1
      end
    end