code: func (p *DynamicForwardedPort) ToString() string {
  	sport := strconv.Itoa(p.SrcPort)
  	if utils.IsLocalhost(p.SrcIP) {
  		return sport
  	}
  	return net.JoinHostPort(p.SrcIP, sport)
  }
docs: // ToString returns a string representation of a dynamic port spec, compatible
  // with OpenSSH's -D flag, i.e. "src_host:src_port".