code: func TCPPing(address string) (time.Duration, error) {
  	start := time.Now()
  	conn, err := dialer.DialTimeout("tcp", address, time.Second)
  	if conn != nil {
  		conn.Close()
  	}
  	return time.Since(start), err
  }
docs: // TCPPing returns the duration required to establish a TCP connection
  // to the given host. ICMP packets require root privileges, hence why we use
  // tcp.