Linux2009. 8. 10. 13:28
SYNOPSIS
       ifconfig [interface]
       ifconfig interface [aftype] options | address ...

       [-]broadcast [addr]
              If  the  address argument is given, set the protocol broadcast address for this interface.  Otherwise, set
              (or clear) the IFF_BROADCAST flag for the interface.

ifconfig에서 보면은
# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:00:00:00:00:00
          inet addr:123.45.67.8  Bcast:123.45.127.255  Mask:255.255.192.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8829 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:607276 (593.0 KiB)  TX bytes:1480 (1.4 KiB)
          Interrupt:133

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
위와 같이 나오는데 Bcast라는 항목이 존재한다.
물론 ifconfig에서 설정을 해줄 수도 있지만, 굳이 설정하지 않으면
자동으로 계산해서 값을 넣어준다.

결론 : 그냥 ip와 netmask만 설정하면 된다.
Posted by 구차니