设置网卡混杂模式

设置网卡混杂模式

有时候为嗅探到网络上的数据，需要将网卡设置到混杂模式。进入该模式将网络上

的数据一并抓获，为此在设置nic的混杂模式的时候有诸多方法？通过shell命令来实现：

ifconfig eth1 promisc 设置混杂模式

ifconfig eth1 -promisc 取消混杂模式

www.2cto.com

执行结果如下

[root@localhost tftpboot]# ifconfig

eth6 Link encap:Ethernet HWaddr 08:00:27:70:1D:79

inet6 addr: fe80::a00:27ff:fe70:1d79/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:100124 errors:0 dropped:0 overruns:0 frame:0

TX packets:8795 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:12986638 (12.3 MiB) TX bytes:6452270 (6.1 MiB)

lo Link encap:Local Loopback

inet addr:127.0.0.1 Mask:255.0.0.0

inet6 addr: ::1/128 Scope:Host

UP LOOPBACK RUNNING MTU:16436 Metric:1

RX packets:1303 errors:0 dropped:0 overruns:0 frame:0

TX packets:1303 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:303973 (296.8 KiB) TX bytes:303973 (296.8 KiB)

[root@localhost tftpboot]# ifconfig eth6 promisc

[root@localhost tftpboot]# ifconfig

eth6 Link encap:Ethernet HWaddr 08:00:27:70:1D:79

inet6 addr: fe80::a00:27ff:fe70:1d79/64 Scope:Link

UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1

RX packets:100154 errors:0 dropped:0 overruns:0 frame:0

TX packets:8795 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:13007885 (12.4 MiB) TX bytes:6452270 (6.1 MiB)

lo Link encap:Local Loopback

inet addr:127.0.0.1 Mask:255.0.0.0

inet6 addr: ::1/128 Scope:Host

UP LOOPBACK RUNNING MTU:16436 Metric:1

RX packets:1303 errors:0 dropped:0 overruns:0 frame:0

TX packets:1303 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:303973 (296.8 KiB) TX bytes:303973 (296.8 KiB)

[root@localhost tftpboot]#

也可以通过C语言方式
编程
来实现，

#include <stdio.h>

#include <unistd.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <errno.h>

#include <linux/if_ether.h>

#include <net/if.h>

#include <sys/ioctl.h>

#include <string.h>

#define ETH_NAME "eth1"

int do_promisc(void) {

int f, s;

struct ifreq ifr;

if ( (f=socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)))<0){

return -1;

}

strcpy(ifr.ifr_name, ETH_NAME);

if ((s = ioctl(f, SIOCGIFFLAGS, &ifr))<0){

close(f);

return-1;

}

if(ifr.ifr_flags & IFF_RUNNING){

printf("eth link up\n");

}else{

printf("eth link down\n");

}

ifr.ifr_flags |= IFF_PROMISC;

if ((s = ioctl(f, SIOCSIFFLAGS, &ifr)) < 0){

return -1;

}

printf("Setting interface ::: %s ::: to promisc\n\n", ifr.ifr_name);

return 0;

}

int check_nic(void)

{

struct ifreq ifr;

int skfd = socket(AF_INET, SOCK_DGRAM, 0);

strcpy(ifr.ifr_name, ETH_NAME);

if (ioctl(skfd, SIOCGIFFLAGS, &ifr) < 0)

{

close(skfd);

return -1;

}

if(ifr.ifr_flags & IFF_RUNNING){

printf("link up\n");

close(skfd);

return 0; // 网卡已插上网线

}else {

printf("link down\n");

close(skfd);

return -1;

}

}

int main(void) {

do_promisc();

return 0;

}