因開發需要獲取有線網卡的MAC地址，發現網上獲取的方法多數只能獲取聯網網卡的MAC地址，因此重寫了下Ubuntu 10下測試通過。 下面代碼無論網卡是否連線，都可以獲取MAC地址，稍作修改，可以輸出系統所有的網卡硬件MAC地址，無論是否已經聯網。

getmac.c

/*


getmac.c 

Created on: 2010-11-4 
Author: carl 
*/ 

include <stdio.h>
include <fcntl.h>
include <stdlib.h>
include <string.h>
include <unistd.h>
include <sys/ioctl.h>
include <sys/types.h>
include <sys/socket.h>
include <netinet/in.h>
include <linux/if.h>
define IFNAMSIZ 16
// data structs to store interface name list 
char ifname_buf[2048]; 
char *ifnames = ifname_buf; 
int count = 0;
void add_interface_name(const char  name) 
{ 
    int i; 
    for (i=0;i<count;i++) 
    { 
        if (!strcmp(ifnames+iIFNAMSIZ, name)) 
            return; 
    } 
    strncpy(ifnames+(count++)*IFNAMSIZ, name, IFNAMSIZ-1); 
}
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; 
}
// get /proc/net/dev interface name list into buffer 
// return 0 if success 
int get_procnet_list() 
{ 
    FILE *fh; 
    char buf[512]; 
    fh = fopen("/proc/net/dev", "r"); 
    if (!fh) 
        return -1;

fgets(buf, sizeof buf, fh); /* eat title lines */ 
fgets(buf, sizeof buf, fh); 
while (fgets(buf, sizeof buf, fh)) 
{ 
    char name[IFNAMSIZ]; 
    get_name(name, buf); 
    add_interface_name(name); 
} 
fclose(fh); 
return 0; 

}
long mac_addr_sys ( u_char addr) 
{ 
/ implementation for Linux / 
    struct ifreq ifr; 
    struct ifreq IFR; 
    struct ifconf ifc; 
    char buf[1024]; 
    int s, i; 
    int ok = 0;

// clear buffer 
memset(ifname_buf, 0, sizeof(ifname_buf)); 

s = socket(AF_INET, SOCK_DGRAM, 0); 
if (s==-1) { 
    return -1; 
} 

ifc.ifc_len = sizeof(buf); 
ifc.ifc_buf = buf; 
ioctl(s, SIOCGIFCONF, &ifc); 

IFR = ifc.ifc_req; 
// put the ioctl interface names in the list 
for (i = ifc.ifc_len / sizeof(struct ifreq); --i >= 0; IFR++) { 
        add_interface_name(IFR->ifr_name); 
} 
// put the /proc/net/dev interface names in the list 
if (get_procnet_list()) 
    return -1; 

// get the first mac address of eth* device hardware address 
for (i = 0; i < count; i++) { 
    strcpy(ifr.ifr_name, ifnames + i*IFNAMSIZ); 
    if (!strncmp(ifr.ifr_name, "eth", 3)) 
        if (ioctl(s, SIOCGIFFLAGS, &ifr) == 0) { 
            if (! (ifr.ifr_flags & IFF_LOOPBACK)) { 
                if (ioctl(s, SIOCGIFHWADDR, &ifr) == 0) { 
                    char *p = (char *)ifr.ifr_hwaddr.sa_data; 
                    if (!*((int *)p) && !*((int *)(p+2)) ) 
                        continue; 
                    // if not 00:00:00:00:00:00, yes, we get the real mac addr 
                    ok = 1; 
                    break; 
                } 
            } 
        } 
} 

close(s); 
if (ok) { 
    bcopy( ifr.ifr_hwaddr.sa_data, addr, 6); 
} 
else { 
    return -1; 
} 
return 0; 

}
/***/ 
/*

Main (only for testing) 
*/ 
int main( int argc, char **argv) 
{ 
 long stat; 
 int i; 
 u_char addr[6];
stat = mac_addr_sys( addr); 
 if (0 == stat) {

 printf( "MAC address = "); 
 for (i=0; i<6; ++i) { 
     printf("%2.2x", addr[i]); 
     if (i<5) 
         printf(":"); 
 } 
 printf( "\n"); 

} 
 else {

 fprintf( stderr, "can't get MAC address\n"); 
 exit( 1); 

} 
 return 0; 
} </pre>