1.读取网卡mac地址
可以通过ioctl(sock,SIOCGIFHHWADDR，&ifr)读取mac地址，对任意类型的socket都适用，只需指定第三参数struct ifreq ifr的ifr.ifr_name,这个ifr_name就是网络设备的名字，如eth0,eth1,lo等，在/proc/net/dev可找到，ioctl通过ifr_name获取设备信息。
struct ifreq ifr;
strncpy(ifr.ifr_name,name,6);
if(ioctl(sock,SIOCGIFHHWADDR，&ifr) < 0)
{
perror("get_hwaddr ioctl:");
close(sock);
return -1;
}
具体实现：
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h> // to avoid warning at inet_ntoa
#include <net/if.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
void printhex(void *hex, int len, char *tag)
{
int i;
unsigned char *p = (unsigned char *)hex;
if(len < 1)
return;
for(i = 0; i < len - 1; i++){
if(*p < 0x10)
printf("0%x%s", *p++, tag);
else
printf("%2x%s", *p++, tag);
}
if(*p < 0x10)
printf("0%x\n", *p++);
else
printf("%2x\n", *p++);
}
int main(int argc,char* argv[])
{
struct ifreq ifr;
unsigned char memzero[6];
int sock;
unsigned char hwaddr[6] = {0};
char *name = "enp0s3";
if(name == NULL || hwaddr == NULL)
{
printf("get_hwaddr:NULL para\n");
//return -1;
}
sock = socket(AF_INET,SOCK_STREAM,0);
if(sock < 0)
{
printf("get_hwaddr:socket error");
}
// get eth1 mac addr
memset(hwaddr,0,6);
memset(&ifr,0,sizeof(ifr));
strncpy(ifr.ifr_name,name,6);
if(ioctl(sock,SIOCGIFHWADDR,&ifr) < 0)
{
perror("get_hwaddr ioctl:");
close(sock);
return -1;
}
else
{
memcpy(hwaddr,ifr.ifr_hwaddr.sa_data,6);
printf("hwaddr:");
printhex(hwaddr, 6, ":");
}
memset(memzero,0,6);
if(memcmp(memzero,hwaddr,6) == 0)
{
printf("no mac\n");
return -1;
}
close(sock);
return 0;
}
运行结果：
hwaddr: 8 : 0 : 27 : c9 : 2e : 9b
2.raw socket收发底层网络数据包
2.1 创建raw socket
int sock = socket(PF_PACKET,SOCK_RAW,htons(ETH_P_ALL));
if(sock < 0)
{
perror("sock");
return -1;
}
第三个参数htons(ETH_P_ALL)只对recvfrom有意义。用这个socket发送的数据，都需要自己维护数据包协议首部，包括网络数据包中的mac地址。
2.2 发送数据包
2.2.1 发送数据包函数原型
int sendto(int s,const void *buf,int len,unsigned int flags,
const struct sockaddr *to,int tolen);
2.2.2 返回值
成功则返回实际传送出去的字符数，失败返回-1，错误原因会存在于errno中
2.2.3 参数说明
s：socket描述符；
buf：rawsocket数据包缓存区(包含待发送数据)
len：rawsocket数据包的长度
flags：调用方式标志位(一般设置为0)
to：指向接收数据的主机地址信息的结构体(sockaddr_in需要进行类型转换)
tolen: to所指结构体的长度
2.2.4 使用方法
struct sockaddr_ll sll;
memset(&sll,0,sizeof(sll));
sll.sll_ifindex = 2; // 指定网卡
if(sendto(sock,packet_start,sizeof(packet_start),0,&sll,sizeof(sll)) < 0)
{
perror("sendto");
return 1;
}
sendto发送原始数据包，只需用struct sockaddr_ll的sll_ifindex指定网卡。
2.2.5 代码实例
发送raw socket(rawsocket_send.c):
#include <sys/socket.h>
#include <string.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <features.h> /* for the glibc version number */
#include <asm/types.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h> /* The L2 protocols */
#include <stdio.h>
#include <netinet/in.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <errno.h>
#define _PATH_PROCNET_DEV "/proc/net/dev"
static char *get_name(char *name, char *p)
{
while (isspace(*p))
p++;
while (*p) {
if (isspace(*p))
break;
if (*p == ':') { /* could be an alias */
char *dot = p, *dotname = name;
*name++ = *p++;
while (isdigit(*p))
*name++ = *p++;
if (*p != ':') { /* it wasn't, backup */
p = dot;
name = dotname;
}
if (*p == '\0')
return NULL;
p++;
break;
}
*name++ = *p++;
}
*name++ = '\0';
return p;
}
/**
* read_netdev_proc - read net dev names form proc/net/dev
* @devname: where to store dev names, devname[num][len]
*/
static int read_netdev_proc(void *devname, const int num, const int len)
{
FILE *fh;
char buf[512];
int cnt = 0;
char *dev = (char *)devname;
if(devname == NULL || num < 1 || len < 4){
printf("read_netdev_proc: para error\n");
return -1;
}
memset(devname, 0, len * num);
fh = fopen(_PATH_PROCNET_DEV, "r");
if (!fh) {
fprintf(stderr, "Warning: cannot open %s (%s). Limited output.\n",
_PATH_PROCNET_DEV, strerror(errno));
return -1;
}
fgets(buf, sizeof buf, fh); /* eat two line */
fgets(buf, sizeof buf, fh);
cnt = 0;
while (fgets(buf, sizeof buf, fh) && cnt < num) {
char *s, name[IFNAMSIZ];
s = get_name(name, buf);
strncpy(devname, name, len);
devname += len;
printf("get_name: %s\n", name);
}
if (ferror(fh)) {
perror(_PATH_PROCNET_DEV);
}
fclose(fh);
return 0;
}
/**
* get_hwaddr - get netdevice mac addr
* @name: device name, e.g: eth0
* @hwaddr: where to save mac, 6 byte hwaddr[6]
* @return: 0 on success, -1 on failure
*/
int get_hwaddr(char *name, unsigned char *hwaddr)
{
struct ifreq ifr;
unsigned char memzero[6];
int sock;
if(name == NULL || hwaddr == NULL){
printf("get_hwaddr: NULL para\n");
return -1;
}
sock = socket(AF_INET, SOCK_STREAM, 0);
if(sock < 0){
printf("get_hwaddr: socket error\n");
//return -1;
}
//get eth1 mac addr
memset(hwaddr, 0, 6);
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, name, 6);
if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0){
perror("get_hwaddr ioctl:");
close(sock);
return -1;
} else {
memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, 6);
//printf("hwaddr: %2x : %2x : %2x : %2x : %2x : %2x\n", hwaddr[0], hwaddr[1],hwaddr[2], hwaddr[3],hwaddr[4], hwaddr[5]);
}
memset(memzero, 0, 6);
if(memcmp(memzero, hwaddr, 6) == 0){
printf("no mac\n");
return -1;
}
close(sock);
return 0;
}
unsigned char packet_start[]={
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,//dst mac
0x00, 0x23, 0x54, 0x0e, 0xe5, 0xd8,//src mac
0x88, 0x8e, //Type: 802.1x authentication
0x01, //Version:v1
0x01, //Type: Start (1)
0x00, 0x00//Length 0
};
void printhex(void *hex, int len, char *tag)
{
int i;
unsigned char *p = (unsigned char *)hex;
if(len < 1)
return;
for(i = 0; i < len - 1; i++){
if(*p < 0x10)
printf("0%x%s", *p++, tag);
else
printf("%2x%s", *p++, tag);
}
if(*p < 0x10)
printf("0%x\n", *p++);
else
printf("%2x\n", *p++);
}
int main(int argc, char **argv)
{
int i;
unsigned char hwaddr[6];
char devname[3][7];
unsigned char buf[1024]; // for revevied packet
int ret;
read_netdev_proc(devname, 3, 7);
for(i = 0; i < 3 && get_hwaddr(devname[i], hwaddr) != 0; i++){
//empty
}
printf("devname: [ %s ]\t", devname[i]);
printhex(hwaddr, 6, ":");
int sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if(sock < 0){
perror("sock");
return -1;
}
struct sockaddr_ll sll;
memset(&sll, 0, sizeof(sll));
sll.sll_ifindex = 2; // It seems only need this to specify whiAWSch NIC to use
memcpy(packet_start + 6, hwaddr, 6);
while(1){
if (sendto(sock, packet_start, sizeof packet_start, 0, &sll, sizeof(sll)) < 0){
perror("sendto");
return 1;
}
printf("Sendto Success!\n");
sleep(1);
}
return 0;
}
2.3 接收数据包
2.3.1 接收数据包函数原型
int recvfrom(int s,void *buf,int len,unsigned int flags,
struct sockaddr *from,int *fromlen)
2.3.2 返回值
成功则返回实际接收到的字符数，失败返回-1,错误原因存于errno中。
2.3.3 参数说明
s: socket描述符
buf: rawsocket数据报缓存区(包含所接收的数据)
len: 缓冲区长度
flags: 调用操作方式(一般设置为0)
from：指向发送数据的客户端地址信息的结构体(sockaddr_in需类型和转换)
fromlen:指针，指向from结构体长度值
2.3.4 使用方法
ret = recvfrom(sock,buf,1024,0,NULL,NULL);
2.3.5 代码示例
接收raw socket(rawsocket_recv.c):
#include <sys/socket.h>
#include <string.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <features.h> /* for the glibc version number */
#include <asm/types.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h> /* The L2 protocols */
#include <stdio.h>
#include <netinet/in.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <errno.h>
void printhex(void *hex, int len, char *tag)
{
int i;
unsigned char *p = (unsigned char *)hex;
if(len < 1)
return;
for(i = 0; i < len - 1; i++){
if(*p < 0x10)
printf("0%x%s", *p++, tag);
else
printf("%2x%s", *p++, tag);
}
if(*p < 0x10)
printf("0%x\n", *p++);
else
printf("%2x\n", *p++);
}
int main(int argc, char **argv)
{
int i;
unsigned char hwaddr[6];
char devname[3][7];
unsigned char buf[1024]; // for revevied packet
int ret;
int sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if(sock < 0){
perror("sock");
return -1;
}
while(1){
ret = recvfrom(sock, buf, 1024, 0, NULL, NULL);
printf("recv: ");
printhex(buf, ret, " ");
}
return 0;
}
将以上两份代码编译生成两个可执行程序：
gcc rawsocket_send.c -o rawsocket_send
gcc rawsocket_recv.c -o rawsocket_recv
手动执行收发程序：
sudo ./rawsocket_send
sudo ./rawsocket_recv
运行结果：
发送端
接收端
wireshark抓取报文
参考文章：
读取linux下的网络设备的mac地址与发送原始数据包_linux检查报文源mac-CSDN博客
UDP协议 sendto 和 recvfrom 浅析与示例 - 阳光长脸兽 - 博客园 (cnblogs.com)
标签：片段,name,int,sock,网络协议,char,Linux,hwaddr,include From： https://www.cnblogs.com/Wangzx000/p/18292170