linux下检测网卡与网线连通状态

1、(只能针对100M网卡)：

/* Check network adapter is up or down */

// Note: one or two adapter drivers may be not support this method
// exemple: based virtual machine

#include
#include
#include
#include
#include
#include
#include
#include

const char* VERSION = "0.6.0.48 --maintain by isnowran";

struct mii_data
{
        __u16 phy_id;
        __u16 reg_num;
        __u16 val_in;
        __u16 val_out;
};

int main( int argc, char* argv[] )
{
        if( argc != 2 )
        {
                printf( "Version: %s\n", VERSION );
                printf( "Useage: argv[0] ethNO.\n" );
                return 0;
        }

        int skfd = 0;
        if( ( skfd = socket( AF_INET, SOCK_DGRAM, 0 ) ) < 0 )
        {
                perror( "socket" );
                return -1;
        }

        struct ifreq ifr;
        bzero( &ifr, sizeof( ifr ) );
        strncpy( ifr.ifr_name, argv[1], IFNAMSIZ - 1 );
        ifr.ifr_name[IFNAMSIZ - 1] = 0;
        if( ioctl( skfd, SIOCGMIIPHY, &ifr ) < 0 )
        {
                perror( "ioctl" );
                return -1;
        }

        struct mii_data* mii = NULL;
        mii = (struct mii_data*)&ifr.ifr_data;
        mii->reg_num = 0x01;
        if( ioctl( skfd, SIOCGMIIREG, &ifr ) < 0 )
        {
                perror( "ioctl2" );
                return -1;
        }

        if( mii->val_out & 0x0004 )
                printf( "Linkup\n" );
        else
                printf( "Linkdown\n" );

        close( skfd );
        return 0;

}

 2、Linux_stat.c

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#include    
#include    
#include    
#include    
#include    
#include    
#include    
#include    
#include    
#include    
#include    
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;   
}  
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
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;
}

3、在linux下使用ifconfig命令能很方便的查看网卡与网线是否连通，运行ifconfig eth0命令大致输出如下：

# 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
#include
#include
#include

/**********************************************************************
* 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;
}

 

下面是编译运行程序的输出结果（正常返回1，断开返回-1）：
# cc netstat.c 
# ./a.out 
NetStat = 1

4、用C编程实现检测网卡是否连上网线

#include   // IFF_RUNNING
#include
#include
#include
#include

int main()
{
    if(check_nic("eth0") == 0)
        printf("detect ok./n");
    else
        printf("detect fail./n");
}

//如果网卡已连上网线，返回0，否则返回-1.
int check_nic(char *nic_name)
{
        struct ifreq ifr;
        int skfd = socket(AF_INET, SOCK_DGRAM, 0);

        strcpy(ifr.ifr_name, nic_name);
        if (ioctl(skfd, SIOCGIFFLAGS, &ifr) < 0)
        {
                return -1;
        }
        if(ifr.ifr_flags & IFF_RUNNING)
                return 0;  // 网卡已插上网线
else return -1;
}

5、Linux命令检测网卡是否连上网线

root# ethtool eth0