text: #ifndef _IP_CT_TFTP
  #define _IP_CT_TFTP
  
  #define TFTP_PORT 69
  
  struct tftphdr {
  	u_int16_t opcode;
  };
  
  #define TFTP_OPCODE_READ	1
  #define TFTP_OPCODE_WRITE	2
  #define TFTP_OPCODE_DATA	3
  #define TFTP_OPCODE_ACK		4
  #define TFTP_OPCODE_ERROR	5
  
  extern unsigned int (*ip_nat_tftp_hook)(struct sk_buff **pskb,
  				 enum ip_conntrack_info ctinfo,
  				 struct ip_conntrack_expect *exp);
  
  #endif /* _IP_CT_TFTP */
  