class Net::SSH::Connection::Keepalive

def send_as_needed(readers, writers)
  return unless readers.nil? && writers.nil?
  return unless should_send?
  info { "sending keepalive #{@unresponded_keepalive_count}" }
  @unresponded_keepalive_count += 1
  @session.send_global_request("keepalive@openssh.com") { |success, response|
    debug { "keepalive response successful. Missed #{@unresponded_keepalive_count-1} keepalives" }
    @unresponded_keepalive_count = 0
  }
  @last_keepalive_sent_at = Time.now
  if keepalive_maxcount > 0 && @unresponded_keepalive_count > keepalive_maxcount
    error { "Timeout, server #{@session.host} not responding. Missed #{@unresponded_keepalive_count-1} timeouts." }
    @unresponded_keepalive_count = 0
    raise Net::SSH::Timeout, "Timeout, server #{@session.host} not responding."
  end
end