ping的原理就是首先建立通道，然后發(fā)送包，對(duì)方接受后返回信息，這個(gè)包至少包括以下內(nèi)容，發(fā)送的時(shí)候，包的內(nèi)容包括對(duì)方的ip地址和自己的地址，還有序列數(shù)，回送的時(shí)候包括雙方地址，還有時(shí)間等，主要是接受方在都是在操作系統(tǒng)內(nèi)核里做好的，時(shí)刻在監(jiān)聽(tīng)，提供一段c程序的代碼，希望對(duì)大家有用。

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

#define packet_size 4096
#define max_wait_time 5
#define max_no_packets 3

char sendpacket[packet_size];
char recvpacket[packet_size];
int sockfd,datalen=56;
int nsend=0,nreceived=0;
struct sockaddr_in dest_addr;
pid_t pid;
struct sockaddr_in from;
struct timeval tvrecv;

void statistics(int signo);
unsigned short cal_chksum(unsigned short *addr,int len);
int pack(int pack_no);
void send_packet(void);
void recv_packet(void);
int unpack(char *buf,int len);
void tv_sub(struct timeval *out,struct timeval *in);

void statistics(int signo)
{ printf("\n--------------------ping statistics-------------------\n");
printf("%d packets transmitted, %d received , %%%d lost\n",nsend,nreceived,
(nsend-nreceived)/nsend*100);
close(sockfd);
exit(1);
}

/*校驗(yàn)和算法*/
unsigned short cal_chksum(unsigned short *addr,int len)
{ int nleft=len;
int sum=0;
unsigned short *w=addr;
unsigned short answer=0;

/*把icmp報(bào)頭二進(jìn)制數(shù)據(jù)以2字節(jié)為單位累加起來(lái)*/
while(nleft>1)
{ sum+=*w++;
nleft-=2;
}