如何使用ioctl函数获取客户端的MAC地址？

Question

我想捕获所有请求我的服务器的客户端MAC地址。我使用以下程序获取客户端的MAC地址，但显示“ioctl：协议族不支持”。如何获取MAC地址？..

#include<stdio.h> 
#include<sys/socket.h> 
#include<sys/types.h> 
#include<netinet/in.h> 
#include<netdb.h> 
#include<errno.h> 
#include<string.h> 
#include<netinet/if_ether.h> 
#include<net/if.h> 
#include<linux/sockios.h> 
int main() 
{ 
    int socket1, socket2; 
    socket1 = 0; 
    socket2 = 0; 
    struct sockaddr_in server, client; 
    int returnstatus = 0; 
socket1 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); 
if(socket1 == -1) 
{ 
    perror("socket()"); 
} 

server.sin_family = AF_INET; 
server.sin_addr.s_addr = INADDR_ANY; 
server.sin_port = htons(8888); 
returnstatus = bind(socket1, (struct sockaddr*)&server, sizeof(server)); 
if(returnstatus == -1) 
{ 
    perror("bind()"); 
} 
returnstatus = listen(socket1, 5); 
if(returnstatus == -1) 
{ 
perror("listen()"); 
} 
for(;;) 
{ 
    int buffr[4]; 
    int addrlen, n; 
    addrlen = sizeof(client); 
    socket2 = accept(socket1, (struct sockaddr *)&client, &addrlen); 
    printf("%s\n",inet_ntoa(client.sin_addr)); 
    printf("%d\n",(int) ntohs(client.sin_port)); 
struct arpreq arpreq_; 
bzero(&arpreq_, sizeof(struct arpreq)); 

if((n = ioctl(socket2, SIOCGARP, &arpreq_)) < 0){ 
perror("ioctl"); 
} 

unsigned char *ptr = &arpreq_.arp_ha.sa_data[0]; 
printf("MAC: %x:%x:%x:%x:%x:%x\n", *ptr, *(ptr+1), *(ptr+2), *(ptr+3), 
*(ptr+4), *(ptr+5)); 

if (socket2 == -1) 
{ 
    perror("accept()"); 
} 
returnstatus = read(socket2, buffr, sizeof(buffr)); 

if(returnstatus == -1) 
{ 
    perror("read()"); 
} 
int c[2]; 
int *w; 
c[0] = buffr[0] + buffr[1]; 
w = c; 
returnstatus = write(socket2, w, sizeof(c)); 
if(returnstatus == -1) 
{ 
perror("write()"); 
} 
close(socket2); 

} 
close(socket1); 
return 0; 
} 

int addition(int x, int y) 
{ 
int z; 
z = x + y; 
return(z); 
} 

Answer 1

随着ioctl(SIOCGARP)你可能会得到本地子网的唯一MAC地址，因为SIOCGARP将从本地的ARP表中返回的MAC地址。

您正在使用SIOCGARP一点点错误的方式。 SIOCGARP的论点是一种投入产出类型。因此，在致电ioctl之前，您必须填写arpreq_的一些字段。 见man page。

当对等设备不在以太网子网中时，流量将通过路由器传输，对等设备可能位于以太网或不在（例如：手机）。所以从每个对等体获得以太网MAC地址是不可能的。

当你主机与对等体通信时，使用第一个路由器的MAC地址。

Answer 2

我有一些代码似乎做你想做的。

我一直在试图获得一些C++代码，它将从我的网络上的远程计算机获取MAC地址。花了相当长的时间才弄明白这一点。我设法将几个示例合并并修改为一个工作演示。修改这个以使用Socket连接应该很容易。

这段代码将网络设备和IP地址作为参数。 （例如192.168.1.1的eth0）

程序将检查IP的正确性，则它将ping IP地址将其添加到ARP表中，那么它会提取从ARP表中的MAC地址，那么它将显示MAC地址。

我不是一个C++编码器（或者至少我是一个新手），所以代码可能会被刷新。

此代码仅在Raspbian上进行过测试！

#include <errno.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <sys/socket.h> 
#include <sys/ioctl.h> 
#include <net/if_arp.h> 
#include <arpa/inet.h> 
#include <sstream> 


bool isValidIpAddress(char *ipAddress) { 
    int result = 0; 
    struct sockaddr_in sa; 
    result = inet_pton(AF_INET, ipAddress, &(sa.sin_addr)); 
    return result; 
} 

/** 
* @brief Convert String to Number 
*/ 
template <typename TP> 
TP str2num(std::string const& value){ 
    std::stringstream sin; 
    sin << value; 
    TP output; 
    sin >> output; 
    return output; 
} 

/** 
* @brief Convert number to string 
*/ 
template <typename TP> 
std::string num2str(TP const& value){ 
    std::stringstream sin; 
    sin << value; 
    return sin.str(); 
} 

/** 
* @brief Execute Generic Shell Command 
* 
* @param[in] command Command to execute. 
* @param[out] output Shell output. 
* @param[in] mode read/write access 
* 
* @return 0 for success, 1 otherwise. 
* 
*/ 
int Execute_Command(const std::string& command, 
    std::string& output, 
    const std::string& mode = "r") { 

    // Create the stringstream 
    std::stringstream sout; 

    // Run Popen 
    FILE *in; 
    char buff[512]; 

    // Test output 
    if(!(in = popen(command.c_str(), mode.c_str()))){ 
     return 1; 
    } 

    // Parse output 
    while(fgets(buff, sizeof(buff), in)!=NULL){ 
     sout << buff; 
    } 

    // Close 
    int exit_code = pclose(in); 

    // set output 
    output = sout.str(); 

    // Return exit code 
    return exit_code; 
} 

/** 
* @brief Ping 
* 
* @param[in] address Address to ping. 
* @param[in] max_attempts Number of attempts to try and ping. 
* @param[out] details Details of failure if one occurs. 
* 
* @return True if responsive, false otherwise. 
* 
* @note { I am redirecting stderr to stdout. I would recommend 
*   capturing this information separately.} 
*/ 
bool Ping(const std::string& address) { 
    // Format a command string 
    std::string command = "ping -c " + num2str(2) + " " + address + " 2>&1"; 
    std::string output; 
    std::string details; 

    // Execute the ping command 
    int code = Execute_Command(command, details); 
    return (code == 0); 
} 


static char *ethernet_mactoa(struct sockaddr *addr) { 
    static char buff[256]; 
    unsigned char *ptr = (unsigned char *) addr->sa_data; 

    sprintf(buff, "%02X:%02X:%02X:%02X:%02X:%02X", 
     (ptr[0] & 0xff), (ptr[1] & 0xff), (ptr[2] & 0xff), 
     (ptr[3] & 0xff), (ptr[4] & 0xff), (ptr[5] & 0xff)); 

    return (buff); 
} 


int main(int argc, char *argv[]) { 
    int s; 
    struct arpreq areq; 
    struct sockaddr_in *sin; 
    struct in_addr ipaddr; 

    if (argc != 3) { 
     fprintf(stderr, "-- Usage: %s device ipaddress\n", argv[0]); 
     exit(1); 
    } 

    /* Get an internet domain socket. */ 
    if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 
     perror("socket"); 
     exit(1); 
    } 


    if (!isValidIpAddress(argv[2])) { 
     fprintf(stderr, "-- Error: invalid IP Address '%s'.\n", 
      argv[2]); 
     exit(1); 
    } 

    if (inet_aton(argv[2], &ipaddr) == 0) { 
     fprintf(stderr, "-- Error: bad dotted-decimal IP '%s'.\n", 
      argv[2]); 
     exit(1); 
    } 

    /* Ping the Address for ARP table listing */ 

    if (!Ping(argv[2])) { 
     fprintf(stderr, "-- Error: unable to ping IP '%s'.\n", 
      argv[2]); 
     exit(1); 
    } 

    /* Make the ARP request. */ 
    memset(&areq, 0, sizeof(areq)); 
    sin = (struct sockaddr_in *) &areq.arp_pa; 
    sin->sin_family = AF_INET; 

    sin->sin_addr = ipaddr; 
    sin = (struct sockaddr_in *) &areq.arp_ha; 
    sin->sin_family = ARPHRD_ETHER; 

    strncpy(areq.arp_dev, argv[1], 15); 

    if (ioctl(s, SIOCGARP, (caddr_t) &areq) == -1) { 
     perror("-- Error: unable to make ARP request, error"); 
     exit(1); 
    } 

    printf("%s -> %s\n", 
    inet_ntoa(((struct sockaddr_in *) &areq.arp_pa)->sin_addr), 
    ethernet_mactoa(&areq.arp_ha)); 

    return 0; 
}