假设CentOS缺省网关是74.86.49.129，通常做法
# vi /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=yes
HOSTNAME=wan.nixcraft.in
GATEWAY=74.86.49.129
# /etc/init.d/networking restart
也可以通过setup程序设置网卡的缺省网关，但在有多块网卡的情况下，总是最后一块网卡的缺省网关有效，有时候这并不符合我们的期望。
根据网卡设置路由的方法是编辑 /etc/sysconfig/network-scripts/route-eth* 文件，
Open /etc/sysconfig/network and append
GATEWAY=eth0.gateway.IP.address
Open /etc/sysconfig/network-scripts/route-eth1 and add routing for eth1 and restart it. For example:
202.54.1.2/29 via 202.54.2.254
Also, set static route for /etc/sysconfig/network-scripts/route-eth0:
10.1.2.3/8 via 10.10.38.95
Do not add gateway entries to /etc/sysconfig/network-scripts/ifcfg-eth1 and /etc/sysconfig/network-scripts/ifcfg-eth0