code: func ClearEntriesForPort(execer exec.Interface, port int, isIPv6 bool, protocol v1.Protocol) error {
  	if port <= 0 {
  		return fmt.Errorf("Wrong port number. The port number must be greater than zero")
  	}
  	parameters := parametersWithFamily(isIPv6, "-D", "-p", protoStr(protocol), "--dport", strconv.Itoa(port))
  	err := Exec(execer, parameters...)
  	if err != nil && !strings.Contains(err.Error(), NoConnectionToDelete) {
  		return fmt.Errorf("error deleting conntrack entries for UDP port: %d, error: %v", port, err)
  	}
  	return nil
  }
docs: // ClearEntriesForPort uses the conntrack tool to delete the conntrack entries
  // for connections specified by the port.
  // When a packet arrives, it will not go through NAT table again, because it is not "the first" packet.
  // The solution is clearing the conntrack. Known issues:
  // https://github.com/docker/docker/issues/8795
  // https://github.com/kubernetes/kubernetes/issues/31983