设置IP和掩码  
ifconfig eth0 192.168.5.40 netmask 255.255.255.0  
设置网关  
route add default gw 192.168.5.1


route add -net 192.168.3.0/24 dev eth0
route add -net 192.168.2.0/24 gw 192.168.3.254