void icmp_protocol (unsigned char * icmp_data) 
{
Struct icmp_header * icmp_protocol; 
Icmp_data icmp_protocol=(struct icmp_header *); 
Printf (" -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- the Transport Layer: the Internet Control Message Protocol -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- \ n "); 
The switch (icmp_protocol - & gt; Type) {
Case 0: 
Printf (" Type: 0 (Echo (ping) the reply) \ n "); 
Printf (" Code: % d \ nChecksum: 0 x % 4 x \ n ", icmp_protocol - & gt; Code, ntohs (icmp_protocol - & gt; Checksum)); 
break; 
Case 8: 
Printf (" Type: 8 (Echo request (ping)) \ n "); 
Printf (" Code: % d \ nChecksum: 0 x % 4 x \ n ", icmp_protocol - & gt; Code, ntohs (icmp_protocol - & gt; Checksum)); 
break; 
Case 3: 
Printf (" Type: 3 (Destination unreachable) \ n "); 
The switch (icmp_protocol - & gt; Code) {
Case 1: 
Printf (" Code: 1 (Host unreachable) \ nChecksum: 0 x % 4 x ", ntohs (icmp_protocol - & gt; Checksum)); 
break; 
Case 3: 
Printf (" Code: 3 (Port unreachable) \ nChecksum: 0 x % 4 x ", ntohs (icmp_protocol - & gt; Checksum)); 
break; 
Case 4: 
Printf (" Code: 4 (Need sliced) \ nChecksum: 0 x % 4 x ", ntohs (icmp_protocol - & gt; Checksum)); 
break; 
Default: 
Printf (" Unknow code \ n "); 
break; 
} 
Case 11: 
Printf (" Type: 11 (Survival time timeout) "); 
Printf (" Code: % d \ nChecksum: 0 x % 4 x ", icmp_protocol - & gt; Code, ntohs (icmp_protocol - & gt; Checksum)); 
break; 
Default: 
Printf (" Unknow type \ n "); 
break; 
} 
Printf (" Identifier (BE) : % d "(0 x % 4 x), ntohs (icmp_protocol - & gt; Icd_id), ntohs (icmp_protocol - & gt; Icd_id)); 
Printf (" Sequence number (BE) : % d "(0 x % 4 x), ntohs (icmp_protocol - & gt; Icd_sequence), ntohs (icmp_protocol - & gt; Icd_sequence)); 
} 

 # # ifndef _BASIC_H_ 
# define _BASIC_H_ 

#include  
#include  
#include  
#include  
#include  
#include  
#include  
#include  
#include  

Struct ether_header 
{
Unsigned char ether_dhost [6].//destination MAC 
Unsigned char ether_shost [6].//source MAC 
Unsigned short ether_type;//Ethernet type 
}; 

Struct ip_header 
{
Unsigned int ip_v: 4;//version 
Unsigned int ip_hl: 4;//the header length 
U_int8_t ip_tos;//the type of service 
U_short ip_len;//total length 
U_short ip_id.//identification 
U_short ip_off;//fragment offset field 
/* # define IP_RF 0 x8000//reserved fragment flag 
# define IP_DF 0 x4000//dont fragment flag 
# define IP_MF 0 x2000//more fragments could flag 
# define IP_OFFMASK 0 x1fff//mask for fragmenting bits */
U_int8_t ip_ttl;//time to live 
U_int8_t ip_p;//protocol 
U_short ip_sum;//checksum 
Struct in_addr ip_src ip_dst;//source and dest address 

}; 

Struct arp_header 
{
Unsigned short int ar_hrd;//the Format of the hardware address. 
Unsigned short int ar_pro;//the Format of protocol address. 
Unsigned char ar_hln;//the Length of the hardware address. 
Unsigned char ar_pln;//Length of protocol address. 
Unsigned short int ar_op;//ARP opcode (command). 
U_int8_t arp_sha [6].//the sender hardware address 
U_int8_t arp_spa [4].//sender protocol address 
U_int8_t arp_tha [6].//the target hardware address 
U_int8_t arp_tpa [4].//the target protocol address 
}; 

Struct rarp_header 
{
Unsigned short int rar_hrd;//the Format of the hardware address. 
Unsigned short int rar_pro;//the Format of protocol address. 
Unsigned char rar_hln;//the Length of the hardware address. 
Unsigned char rar_pln;//Length of protocol address. 
Unsigned short int rar_op;//ARP opcode (command). 
U_int8_t rarp_sha [6].//the sender hardware address 
U_int8_t rarp_spa [4].//sender protocol address 
U_int8_t rarp_tha [6].//the target hardware address 
U_int8_t rarp_tpa [4].//the target protocol address 
}; 

Struct tcp_header 
{
U_int16_t source; 
U_int16_t dest. 
U_int32_t seq. 
U_int32_t ack_seq; 
U_int16_t doff: 4; 
U_int16_t res1:4; 
U_int16_t res2:2; 
U_int16_t urg: 1; 
U_int16_t ack: 1; 
U_int16_t PSH: 1; 
U_int16_t RST: 1; 
U_int16_t syn: 1; 
U_int16_t fin: 1; 
U_int16_t window; 
U_int16_t check; 
U_int16_t urg_ptr; 
}; 

Struct udp_header 
{
U_int16_t sport; 
U_int16_t dport; 
U_int16_t len.//udp length 
U_int16_t check;//checksum 
}; 

Struct icmp_header 
{
U_int8_t type;//the message type 
U_int8_t code;//type sub - code 
U_int16_t checksum.//catalog. 
U_int16_t icd_id; 
U_int16_t icd_sequence; 

/* union 
{
U_char ih_pptr;//icmp_paramprob 
Struct in_addr ih_gwaddr;//gateway address 
Struct ih_idseq//echo datagram 
{
U_int16_t icd_id; 
U_int16_t icd_sequence; 
} ih_idseq; 
U_int32_t ih_void; 

//icmp_unreach_needfrag 
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