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@austinmarton
Created February 27, 2012 08:40
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Send a raw Ethernet frame in Linux
/*
* 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 MY_DEST_MAC0 0x00
#define MY_DEST_MAC1 0x00
#define MY_DEST_MAC2 0x00
#define MY_DEST_MAC3 0x00
#define MY_DEST_MAC4 0x00
#define MY_DEST_MAC5 0x00
#define DEFAULT_IF "eth0"
#define BUF_SIZ 1024
int main(int argc, char *argv[])
{
int sockfd;
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);
/* 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] = MY_DEST_MAC0;
eh->ether_dhost[1] = MY_DEST_MAC1;
eh->ether_dhost[2] = MY_DEST_MAC2;
eh->ether_dhost[3] = MY_DEST_MAC3;
eh->ether_dhost[4] = MY_DEST_MAC4;
eh->ether_dhost[5] = MY_DEST_MAC5;
/* 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] = MY_DEST_MAC0;
socket_address.sll_addr[1] = MY_DEST_MAC1;
socket_address.sll_addr[2] = MY_DEST_MAC2;
socket_address.sll_addr[3] = MY_DEST_MAC3;
socket_address.sll_addr[4] = MY_DEST_MAC4;
socket_address.sll_addr[5] = MY_DEST_MAC5;
/* Send packet */
if (sendto(sockfd, sendbuf, tx_len, 0, (struct sockaddr*)&socket_address, sizeof(struct sockaddr_ll)) < 0)
printf("Send failed\n");
return 0;
}
@nxtxnt
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nxtxnt commented Nov 17, 2018

It works on eth0, but gives "send failed" on wlan0, any idea?

Because it's an ethernet frame ?

@devendranaga
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Hi. I had tried to run the code but i got "socket: Operation not permitted
SIOCGIFINDEX: Bad file descriptor
SIOCGIFHWADDR: Bad file descriptor
Send failed"
I had tried to fix it by using the methods proposed but still no avail. Can anyone guide me?

you dont have a wlan0. what is your wireless interface name ? ifconfig ?

@drafterleo
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How about to add close(sockfd); at the end? :)

@cyantarek
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Is it possible to run the src and destination to the same PC mac address?

@arjunnasa
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what about crc checksum after the payload?

@shahriarbasiri
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Is IPPROTO_RAW a valid option for AF_PACKET SOCK_RAW socket? However it doesn't matter for sending raw ethernet packet:)

@circl-lastname
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circl-lastname commented Mar 29, 2023

By using raw sockets is it possible full duplex communication of Ethernet frames

If your Ethernet controller is in Full Duplex mode then it will always do so regardless, if it's in Half Duplex then no

@mgulsoy
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mgulsoy commented May 23, 2023

Thanks for sharing. It helped a lot.

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