promisc 모드는 무차별 모드로 드랍 없이 모든 패킷을 받아들인다.

# ifconfig    명령을 통해 promisc 모드를 확인/설정을 할 수 있다.

# ifconfig eth0 promisc 와 같이 하면 되고, 설정을 해제하려면

# ifconfig eth0 -promisc 로 실행하면 된다.

[root@server /]# ifconfig

eth0      Link encap:Ethernet  HWaddr 00:C0:9F:37:ED:21  
          inet addr:192.168.1.5  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1273 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:144471 (141.0 Kb)  TX bytes:704 (704.0 b)
          Interrupt:18 Base address:0xece0 Memory:fe1e0000-fe200000

[root@server /]# ifconfig eth0 promisc

[root@server /]# ifconfig

eth0      Link encap:Ethernet  HWaddr 00:C0:9F:37:ED:21  
          inet addr:192.168.1.5  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:4123 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2297712 (2.1 Mb)  TX bytes:704 (704.0 b)
          Interrupt:18 Base address:0xece0 Memory:fe1e0000-fe200000