因开发需要获取有线网卡的MAC地址，发现网上获取的方法多数只能获取联网网卡的MAC地址，因此重写了下Ubuntu 10下测试通过。 下面代码无论网卡是否连线，都可以获取MAC地址，稍作修改，可以输出系统所有的网卡硬件MAC地址，无论是否已经联网。

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+i*IFNAMSIZ, 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;   }