/etc/network/interfaces の書き方
iface eth0 inet static address 192.168.202.100 netmask 255.255.255.0 gateway 192.168.202.1 broadcast 192.168.202.255 network 192.168.202.0
iface eth0 inet static address 192.168.202.100 netmask 255.255.255.0 gateway 192.168.202.1 broadcast 192.168.202.255 network 192.168.202.0