网站服务端：
iptables –F
iptables –F –t nat //清空filter表和nat表
service httpd start
网关：
vim /etc/sysctl.conf
Kernel sysctl configuration file for Red Hat Linux
#
For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and
sysctl.conf(5) for more details.
Controls IP packet forwarding
net.ipv4.ip_forward = 1 //开启路由转发功能
Controls source route verification
net.ipv4.conf.default.rp_filter = 1
iptables –F
iptables -t nat -A POSTROUTING -s 192.168.100.0/24 -o eth0 -j SNAT --to-source 12.0.0.1
//将内部局域网IP地址段转换为全局IP地址
SNAT配置完成
服务端验证转换是否生效
cd /etc/httpd/logs
cat access_log
网关服务器做DNAT：
iptables -t nat -A PREROUTING -d 12.0.0.1 -i eth0 -p tcp --dport 80 -j DNAT --to-destination 192.168.100.10
//允许公网服务器通过网关12.0.0.1访问内部网络192.168.100.10的网站