/*ping program for learning IP protocol    author: jeff    date:    2014/10/25*/#include <stdio.h>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <errno.h>static int ICMP_create();static int opt_set(int sockfd);intmain(int argc, char* argv[]){    int sockfd = ICMP_create();    int optset = 0;    if(sockfd != -1)        printf("create socket ICMP success!\n");    else        printf("create socket ICMP failed [%d]!\n", errno);    optset = opt_set(sockfd);    if(optset != -1)        printf("sock set success\n");    else        printf("sock set failed\n");            return 0;}static int ICMP_create(){    return socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);}static int opt_set(int sockfd){    int on =1;    return setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on));    }