code: func (c *ChainInfo) Prerouting(action Action, args ...string) error {
  	a := []string{"-t", string(Nat), string(action), "PREROUTING"}
  	if len(args) > 0 {
  		a = append(a, args...)
  	}
  	if output, err := Raw(a...); err != nil {
  		return err
  	} else if len(output) != 0 {
  		return ChainError{Chain: "PREROUTING", Output: output}
  	}
  	return nil
  }
docs: // Prerouting adds linking rule to nat/PREROUTING chain.