ソースコード例：Ethernetパケット受信

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
#include <netpacket/packet.h>
#include <netinet/ip.h>
#include <sys/ioctl.h>
#include <net/if.h>

static char buff[ETHER_MAX_LEN];

int main(int argc, char **argv) {
	struct ether_header	*ether;
	struct iphdr		*ip;
	struct ifreq		ifr;
	struct sockaddr_ll	sa;
	char			smac[20], dmac[20];
	char			sip[16], dip[16];
	int			sockfd, len, proto, i, ret;
	unsigned int		saddr, daddr, ipsize;
	char			adrbuf[INET_ADDRSTRLEN + 1];

	if(argc != 2) {
		printf("Usage : %s dev\r", argv[0]);
		return -1;
	}

	sockfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
	if(sockfd < 0) {
		printf("socket error\r");
		return -1;
	}
	memset(&ifr, 0, sizeof(struct ifreq));
	strcpy(ifr.ifr_name, argv[1]);
	ret = ioctl(sockfd, SIOCGIFINDEX, &ifr);
	if(ret < 0) printf("ioctl error\r");
     
 	memset(&sa, 0, sizeof(struct sockaddr_ll));
	sa.sll_family = AF_PACKET;
	sa.sll_halen = ETH_ALEN;
	sa.sll_ifindex = ifr.ifr_ifindex;
	bind(sockfd, (struct sockaddr *)&sa, sizeof(struct sockaddr_ll));

	for(;;) {
		len = recv(sockfd, buff, sizeof(buff), 0);
		if(len < 0){
			printf("recv error\r");
			break;
		}
		ether = (struct ether_header *)buff;
		for(i = 0;i < 6;i++) {
			printf("%02x", ether->ether_shost[i]);
			if(i < 5) putchar(':');
		}
		printf(" --> ");
		for(i = 0;i < 6;i++) {
			printf("%02x", ether->ether_dhost[i]);
			if(i < 5) putchar(':');
		}
		printf(" (%d byte)\r", len);
		proto = ntohs(ether->ether_type);
		switch(proto) {
		case ETHERTYPE_IP:
			ip = (struct iphdr *)(buff + sizeof(struct ether_header));
			saddr = ip->saddr;
			daddr = ip->daddr;
			ipsize = ntohs(ip->tot_len);
			inet_ntop(AF_INET, &saddr, adrbuf, INET_ADDRSTRLEN);
			printf("%s --> ", adrbuf);
			inet_ntop(AF_INET, &daddr, adrbuf, INET_ADDRSTRLEN);
			printf("%s (%d byte)\r", adrbuf, ipsize);
			break;
		case ETHERTYPE_ARP:
			printf("ARP\r");
			break;
		case ETHERTYPE_REVARP:
			printf("Reverse ARP\r");
			break;
		default:
			printf("other protocol\r");
			break;
		}
		for(i = 0;i < len;i++) {
			if((i % 16) == 0) printf("%04x : ", i);
			printf("%02x ", buff[i] & 0xff);
			if((i % 16) == 15) putchar('\r');
		}
		putchar('\r');fflush(stdout);
	}
	close(sockfd);
	return 0;
}