解決辦法：

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <net/if.h>

#include <net/if_arp.h>

#include <sys/ioctl.h>

#include <netinet/in.h>

void err_sys(const char *errmsg);

int getmac(char *out,int sockfd)

{

int i;

struct ifreq ifr;

struct arpreq arpr;

char *p;

strncpy(ifr.ifr_name, "eth0", sizeof(ifr.ifr_name));

/* get hardware address */

ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;

if (ioctl(sockfd, SIOCGIFHWADDR, &ifr) == -1)

return -1;

/* output hardware address */

p=out;

for (i = 0; i < 6; i++) {

unsigned char *mac = (unsigned char *) ifr.ifr_hwaddr.sa_data;

p+=sprintf(p,"%02x", (int) mac);

if (i != 5)

p+=sprintf(p,"%c", ":");

}

return 0;

}

GetIfEntry GetIfTable

下面是例項

http://www.codeproject.com/KB/IP/BytesSentReceived.aspx

bool GetIPV4Gateway(const char * pNICName, char *pGateway, unsigned long len)

{

char buffer[200] = { 0 };

unsigned long bufLen = sizeof(buffer);

unsigned long defaultRoutePara[4] = { 0 };

FILE * pfd = fopen(PATH_ROUTE, "r");

if (NULL == pfd)

{

return false;

}

while (fgets(buffer, bufLen, pfd))

{

sscanf(buffer, "%*s %x %x %x %*x %*x %*x %x %*x %*x %*x\n", (unsigned int *)&defaultRoutePara[1], (unsigned int *)&defaultRoutePara[0], (unsigned int *)&defaultRoutePara[3], (unsigned int *)&defaultRoutePara[2]);

if (NULL != strstr(buffer, pNICName))

{

//如果FLAG標誌中有 RTF_GATEWAY

if (defaultRoutePara[3] & RTF_GATEWAY)

{

unsigned long ip = defaultRoutePara[0];

snprintf(pGateway, len, "%d.%d.%d.%d", (ip & 0xff), (ip >> 8) & 0xff, (ip >> 16) & 0xff, (ip >> 24) & 0xff);

break;

}

}

memset(buffer, 0, bufLen);

}

fclose(pfd);

pfd = NULL;

return true;

}

這裡PATH_ROUTE是/proc/net/route

RTF_GATEWAY需要包括標頭檔案#include <net/route.h>

假設要獲取wifi的閘道器，比如wlan0

char gateway[32] = { 0 };

GetIPV4Gateway("wlan0", gateway, 32);