用ioctl控制，通过SIOCGIFHWADDR获取MAC地址，SIOCSIFHWADDR设置MAC地址，不过在设 置MAC地址之前，要先把网卡down掉，设置好了以后，再UP起来。

#include 
    
       /* for socket(2) and related bits and pieces */#include 
     
       /* for socket(2) */#include 
      
            /* for struct ifreq */#include 
       
         /* for ARPHRD_ETHER */#include 
        
           /* for IOCTL's */#include 
         
           /* for fprintf etc */#include 
          
            /* for close */
          
         
        
       
      
     
    

int main(int argc,char **argv){    struct ifreq ifr;    int skfd;    if (argc<3) 　{        fprintf(stderr,"usage:/n%s interface hwaddr/n",argv[1]);        return 1;    }    /* Fill in the structure */    snprintf(ifr.ifr_name, IFNAMSIZ, "%s", argv[1]);    ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;    /* TODO: write some code to parse argv[2] into ifr.ifr_hwaddr.sa_data */    /* memcpy(&ifr.ifr_hwaddr.sa_data, argv[2], sizeof(ether.address)); */    /* Create a socket fd */    skfd = socket(PF_INET,SOCK_STREAM,0);    /* call the IOCTL */    if (ioctl(skfd, SIOCSIFHWADDR, &ifr) < 0) {        perror("ioctl(SIOCSIFHWADDR)");        return 1;    }