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Receive raw Ethernet frames in Linux
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/* | |
* This program is free software: you can redistribute it and/or modify | |
* it under the terms of the GNU General Public License as published by | |
* the Free Software Foundation, either version 3 of the License, or | |
* (at your option) any later version. | |
*/ | |
#include <arpa/inet.h> | |
#include <linux/if_packet.h> | |
#include <stdio.h> | |
#include <string.h> | |
#include <stdlib.h> | |
#include <sys/ioctl.h> | |
#include <sys/socket.h> | |
#include <net/if.h> | |
#include <netinet/ether.h> | |
#define DEFAULT_IF "eth0" | |
#define BUF_SIZ 1024 | |
uint8_t bytes[6] = {0x11, 0x22, 0x33, 0x44, 0x55, 0x66}; | |
int values[6]; | |
int main(int argc, char *argv[]) | |
{ | |
int sockfd, i; | |
struct ifreq if_idx; | |
struct ifreq if_mac; | |
int tx_len = 0; | |
char sendbuf[BUF_SIZ]; | |
struct ether_header *eh = (struct ether_header *) sendbuf; | |
struct iphdr *iph = (struct iphdr *) (sendbuf + sizeof(struct ether_header)); | |
struct sockaddr_ll socket_address; | |
char ifName[IFNAMSIZ]; | |
/* Get interface name */ | |
if (argc > 1) | |
strcpy(ifName, argv[1]); | |
else | |
strcpy(ifName, DEFAULT_IF); | |
if (argc > 2) | |
if (6 == sscanf(argv[2], "%x:%x:%x:%x:%x:%x%c", | |
&values[0], &values[1], &values[2], | |
&values[3], &values[4], &values[5])) { | |
/* convert to uint8_t */ | |
for(i = 0; i < 6; ++i) | |
bytes[i] = (uint8_t)values[i]; | |
} | |
printf("Sending to MAC %02x:%02x:%02x:%02x:%02x:%02x via %s interface\n", | |
bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], | |
ifName); | |
/* Open RAW socket to send on */ | |
if ((sockfd = socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW)) == -1) { | |
perror("socket"); | |
} | |
/* Get the index of the interface to send on */ | |
memset(&if_idx, 0, sizeof(struct ifreq)); | |
strncpy(if_idx.ifr_name, ifName, IFNAMSIZ-1); | |
if (ioctl(sockfd, SIOCGIFINDEX, &if_idx) < 0) | |
perror("SIOCGIFINDEX"); | |
/* Get the MAC address of the interface to send on */ | |
memset(&if_mac, 0, sizeof(struct ifreq)); | |
strncpy(if_mac.ifr_name, ifName, IFNAMSIZ-1); | |
if (ioctl(sockfd, SIOCGIFHWADDR, &if_mac) < 0) | |
perror("SIOCGIFHWADDR"); | |
/* Construct the Ethernet header */ | |
memset(sendbuf, 0, BUF_SIZ); | |
/* Ethernet header */ | |
eh->ether_shost[0] = ((uint8_t *)&if_mac.ifr_hwaddr.sa_data)[0]; | |
eh->ether_shost[1] = ((uint8_t *)&if_mac.ifr_hwaddr.sa_data)[1]; | |
eh->ether_shost[2] = ((uint8_t *)&if_mac.ifr_hwaddr.sa_data)[2]; | |
eh->ether_shost[3] = ((uint8_t *)&if_mac.ifr_hwaddr.sa_data)[3]; | |
eh->ether_shost[4] = ((uint8_t *)&if_mac.ifr_hwaddr.sa_data)[4]; | |
eh->ether_shost[5] = ((uint8_t *)&if_mac.ifr_hwaddr.sa_data)[5]; | |
eh->ether_dhost[0] = bytes[0]; | |
eh->ether_dhost[1] = bytes[1]; | |
eh->ether_dhost[2] = bytes[2]; | |
eh->ether_dhost[3] = bytes[3]; | |
eh->ether_dhost[4] = bytes[4]; | |
eh->ether_dhost[5] = bytes[5]; | |
/* Ethertype field */ | |
eh->ether_type = htons(ETH_P_IP); | |
tx_len += sizeof(struct ether_header); | |
/* Packet data */ | |
sendbuf[tx_len++] = 0xde; | |
sendbuf[tx_len++] = 0xad; | |
sendbuf[tx_len++] = 0xbe; | |
sendbuf[tx_len++] = 0xef; | |
/* Index of the network device */ | |
socket_address.sll_ifindex = if_idx.ifr_ifindex; | |
/* Address length*/ | |
socket_address.sll_halen = ETH_ALEN; | |
/* Destination MAC */ | |
socket_address.sll_addr[0] = bytes[0]; | |
socket_address.sll_addr[1] = bytes[1]; | |
socket_address.sll_addr[2] = bytes[2]; | |
socket_address.sll_addr[3] = bytes[3]; | |
socket_address.sll_addr[4] = bytes[4]; | |
socket_address.sll_addr[5] = bytes[5]; | |
/* Send packet */ | |
if (sendto(sockfd, sendbuf, tx_len, 0, (struct sockaddr*)&socket_address, sizeof(struct sockaddr_ll)) < 0) | |
printf("Send failed\n"); | |
return 0; | |
} |
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The content looks like it's sender not receiver.