linux 检测网线拨出

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link_stat.c

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <errno.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/socket.h> #include <linux/if.h> #include <linux/sockios.h> #include <linux/ethtool.h> int get_netlink_status(const char *if_name); int main() { if(getuid() != 0) { fprintf(stderr, "Netlink Status Check Need Root Power.\n"); return 1; } printf("Net link status: %d\n", get_netlink_status("eth0")); return 0; } // if_name like "ath0", "eth0". Notice: call this function // need root privilege. // return value: // -1 -- error , details can check errno // 1 -- interface link up // 0 -- interface link down. int get_netlink_status(const char *if_name) { int skfd; struct ifreq ifr; struct ethtool_value edata; edata.cmd = ETHTOOL_GLINK; edata.data = 0; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, if_name, sizeof(ifr.ifr_name) - 1); ifr.ifr_data = (char *) &edata; if (( skfd = socket( AF_INET, SOCK_DGRAM, 0 )) < 0) return -1; if(ioctl( skfd, SIOCETHTOOL, &ifr ) == -1) { close(skfd); return -1; } close(skfd); return edata.data; }

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# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:25:35:68:CC:D6 inet addr:192.168.1.168 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::215:c5ff:fe18:ccd6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:130722 errors:0 dropped:0 overruns:0 frame:0 TX packets:112560 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:104371099 (99.5 MiB) TX bytes:20518584 (19.5 MiB) Interrupt:16

其中的RUNNING就表示网卡与网线正常链接，拔掉网线再运行此命令就会发现RUNNING不在了。
我的目的是用C语言来实现程序，而linux系统提供了popen/pclose进程管道让C和shell很方便的交互，不过使用的时候要注意设置权限，以免造成安全隐患。废话不多说，看下面C代码结合shell命令检测网卡与网线连通状况：
netstat.c

#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> /********************************************************************** * 函数名称： GetNetStat * 功能描述：检测网络链接是否断开 * 输入参数： * 输出参数：无 * 返回值：正常链接1,断开返回-1 * 其它说明：本程序需要超级用户权限才能成功调用ifconfig命令 * 修改日期版本号修改人修改内容 * --------------------------------------------------------------------- * 2010/04/02 V1.0 eden_mgqw ***********************************************************************/ int GetNetStat( ) { char buffer[BUFSIZ]; FILE *read_fp; int chars_read; int ret; memset( buffer, 0, BUFSIZ ); read_fp = popen("ifconfig eth0 | grep RUNNING", "r"); if ( read_fp != NULL ) { chars_read = fread(buffer, sizeof(char), BUFSIZ-1, read_fp); if (chars_read > 0) { ret = 1; } else { ret = -1; } pclose(read_fp); } else { ret = -1; } return ret; } int main() { int i=0; i = GetNetStat(); printf( "\nNetStat = %d\n", i ); return 0; }

转载地址：http://www.cnblogs.com/cute/archive/2011/09/20/2182289.html

#include <ctype.h>;#include <err.h>;#include <errno.h>;#include <stdio.h>;#include <stdlib.h>;#include <string.h>;#include <unistd.h>;#include <sys/ioctl.h>;#include <sys/socket.h>;#include <net/if.h>;#include <net/if_types.h>;#include <net/if_media.h>;intmain(int argc,char **argv) {       int s;        struct ifreq ifr;       struct ifmediareq ifmr;       int *media_list;       char name[IFNAMSIZ];              if(2 != argc){           printf("Usage:\ntest cardname(e.g: vr0)\n");           return 1;       }                  strncpy(name, argv[1], sizeof(name));              ifr.ifr_addr.sa_family = AF_INET;       strncpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));       if ((s = socket(ifr.ifr_addr.sa_family, SOCK_DGRAM, 0)) < 0)               err(1, "socket");       (void) memset(&ifmr, 0, sizeof(ifmr));       (void) strncpy(ifmr.ifm_name, name, sizeof(ifmr.ifm_name));       if (ioctl(s, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0)               err(1, "SIOCGIFMEDIA");       if (ifmr.ifm_count == 0) {               warnx("%s: no media types?", name);               return;       }       media_list = (int *)malloc(ifmr.ifm_count * sizeof(int));       if (media_list == NULL)               err(1, "malloc");       ifmr.ifm_ulist = media_list;       if (ioctl(s, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0)               err(1, "SIOCGIFMEDIA");       if (ifmr.ifm_status & IFM_AVALID) {               printf("\tstatus: ");               switch (IFM_TYPE(ifmr.ifm_active)) {               case IFM_ETHER:                       if (ifmr.ifm_status & IFM_ACTIVE)                               printf("active");                       else                               printf("no carrier");                       break;               case IFM_FDDI:               case IFM_TOKEN:                       if (ifmr.ifm_status & IFM_ACTIVE)                               printf("inserted");                       else                               printf("no ring");                       break;               case IFM_ATM:                       if (ifmr.ifm_status & IFM_ACTIVE)                               printf("active");                       else                               printf("no carrier");                       break;               case IFM_IEEE80211:                       if (ifmr.ifm_status & IFM_ACTIVE)                               printf("associated");                       else                               printf("no carrier");                       break;               }               putchar('\n');       }       free(media_list);       return 0; }

#include <sys/types.h>;  #include <sys/socket.h>;  #include <sys/ioctl.h>;  #include <net/if.h>;  #include <linux/sockios.h>;  #include <linux/types.h>;   struct mii_data {     __u16   phy_id;     __u16   reg_num;     __u16   val_in;     __u16   val_out;  };   int main()  {     int skfd;     struct ifreq ifr;     struct mii_data *mii;      if ((skfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {         perror("socket");         exit(1);     }      strncpy(ifr.ifr_name, "eth0", IFNAMSIZ-1);     ifr.ifr_name[IFNAMSIZ-1] = 0;      if (ioctl(skfd, SIOCGMIIPHY, &ifr) < 0) {         perror("ioctl");         exit(1);     }      mii = (struct mii_data *)&ifr.ifr_data;     mii->;reg_num = 0x01;      if (ioctl(skfd, SIOCGMIIREG, &ifr) < 0) {         perror("ioctl");         exit(1);     }     if (mii->;val_out & 0x0004)         puts("link ok");     else         puts("no link");      close(skfd);      return 0;  }

转载地址：http://bbs.chinaunix.net/thread-618079-1-1.html

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