code: func (p *ForwardedPort) ToString() string {
  	sport := strconv.Itoa(p.SrcPort)
  	dport := strconv.Itoa(p.DestPort)
  	if utils.IsLocalhost(p.SrcIP) {
  		return sport + ":" + net.JoinHostPort(p.DestHost, dport)
  	}
  	return net.JoinHostPort(p.SrcIP, sport) + ":" + net.JoinHostPort(p.DestHost, dport)
  }
docs: // ToString returns a string representation of a forwarded port spec, compatible
  // with OpenSSH's -L  flag, i.e. "src_host:src_port:dest_host:dest_port".