1、首先确保转发开关打开
#vi /etc/sysctl.conf
net.ipv4.ip_forward = 1
#sysctl -p
2、核对双网卡配置
cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
HWADDR=
TYPE=Ethernet
UUID=61e9bdb5-b1ff-4c8f-8c19-938c834de345
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=static
IPADDR=192.8.8.57
NETMASK=255.255.255.224
GATEWAY=192.8.8.62
# cat /etc/sysconfig/network-scripts/ifcfg-eth2
DEVICE=eth2
HWADDR=
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=no
BOOTPROTO=static
IPADDR=11.10.10.2
NETMASK=255.255.255.0
3、执行iptables并保存
# iptables -t nat -A POSTROUTING -s 11.10.10.0/24 -j SNAT --to 192.8.8.57
# service iptables save