添加到主机的路由

route add -host 192.168.1.2 dev eth0:0

route add -host 10.20.30.148 gw 10.20.30.40

添加到网络的路由

route add -net 10.20.30.40 netmask 255.255.255.248 eth0

route add -net 10.20.30.48 netmask 255.255.255.248 gw 10.20.30.41

route add -net 192.168.1.0/24 eth1

添加默认路由

route add default gw 192.168.1.1 //默认只在内存中生效

删除路由

route del -host 192.168.1.2 dev eth0:0

route del -host 10.20.30.148 gw 10.20.30.40

route del -net 10.20.30.40 netmask 255.255.255.248 eth0

route del -net 10.20.30.48 netmask 255.255.255.248 gw 10.20.30.41

route del -net 192.168.1.0/24 eth1

route del default gw 192.168.1.1 //删除所有的默认路由：route del default

设置包转发

vim /etc/sysctl.conf

net.ipv4.ip_forward = 1

sysctl -p

路由永久生效

vim /etc/network/interfaces

auto eth0
iface eth0 inet static
address 192.168.2.1
network 192.168.2.0
netmask 255.255.255.0
broadcast 192.168.2.255
gateway 192.168.2.254
up route add -net 192.168.3.0 netmask 255.255.255.0 gw 192.168.2.2 dev eth0
down route del -net 192.168.3.0 netmask 255.255.255.0 gw 192.168.2.2 dev eth0
up route add -net 192.168.4.0 netmask 255.255.255.0 gw 192.168.2.2 dev eth0
down route del -net 192.168.4.0 netmask 255.255.255.0 gw 192.168.2.2 dev eth0