struct in_addr{
u_long s_addr;
};


struct ether_header{
u_char ether_dhost[6]; //destination host (adresse de destination)
u_char ether_shost[6]; //source host (adresse source)
u_short ether_type;    //type de trame
u_short ether_Htype;
u_short ether_protocol;
u_char ether_HLen;
u_char ether_PLen;
u_short ether_op;
u_char ether_Hsender[6];
struct in_addr ip_src;
u_char ether_Htarget[6];
struct in_addr ip_dst;
};

/* IP header */
struct ip_header{
   #if BYTE_ORDER == LITTLE_ENDIAN
   u_int ip_hl:4, /* header length */
   ip_v:4; /* version */
   #if BYTE_ORDER == BIG_ENDIAN
   u_int ip_v:4, /* version */
   ip_hl:4; /* header length */
   #endif
   #endif /* not _IP_VHL */
   u_char ip_tos; /* type of service */
   u_short ip_len; /* total length */
   u_short ip_id; /* identification */
   u_short ip_off; /* fragment offset field */
   #define IP_RF 0x8000 /* reserved fragment flag */
   #define IP_DF 0x4000 /* dont fragment flag */
   #define IP_MF 0x2000 /* more fragments flag */
   #define IP_OFFMASK 0x1fff /* mask for fragmenting bits */
   u_char ip_ttl; /* time to live */
   u_char ip_p; /* protocol */
   u_short ip_sum; /* checksum */
   struct in_addr ip_src,ip_dst; /* source and dest address */
};