Linux CentOS 6 NAT 转发 完整教程
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网络拓补图：
环境介绍：
一台CentOS6 主机，双网卡，两网段
网口设定如下：
[[email protected] ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 TYPE=Ethernet ONBOOT=yes BOOTPROTO=dhcp [[email protected] ~]# [[email protected] ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 DEVICE=eth1 TYPE=Ethernet ONBOOT=yes BOOTPROTO=static IPADDR=192.168.66.1 NETMASK=255.255.255.0 [[email protected] ~]# service network restart [[email protected] ~]# ifconfig -a eth0 Link encap:Ethernet HWaddr 00:0C:29:37:00:93 inet addr:172.16.20.183 Bcast:172.16.255.255 Mask:255.255.0.0 eth1 Link encap:Ethernet HWaddr 00:0C:29:37:00:9D inet addr:192.168.66.1 Bcast:192.168.66.255 Mask:255.255.255.0
打开网卡转发
[[email protected] ~]# vim /etc/sysctl.conf net.ipv4.ip_forward = 1
立即生效
[[email protected] ~]# sysctl -p
转发规则：
[[email protected] ~]# iptables -t nat -A POSTROUTING -s 192.168.66.0/24 -j SNAT --to 172.16.20.183 #出口为静态IP选这个 [[email protected] ~]# iptables -t nat -A POSTROUTING -s 192.168.66.0/24 -o eth0 -j MASQUERADE #出口为动态IP选这个
查看/保存转发规则
[[email protected] ~]# iptables -t nat -nL [[email protected] ~]# service iptables save
===================验证NAT===============
在192.168.66/24网段内，一台linux主机设置为：
[[email protected] ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 TYPE=Ethernet ONBOOT=yes BOOTPROTO=static IPADDR=192.168.66.2 NETMASK=255.255.255.0 GATEWAY=192.168.66.1 DNS1=180.76.76.76.76 DNS2=8.8.8.8 [[email protected] ~]# 重启网络服务 [[email protected] ~]# service network restart Shutting down interface eth0: [ OK ] Shutting down loopback interface: [ OK ]
开始测试
ping 自己测试 [[email protected] ~]# ping 192.168.66.2 PING 192.168.66.2 (192.168.66.2) 56(84) bytes of data. 64 bytes from 192.168.66.2: icmp_seq=1 ttl=64 time=0.042 ms ping网关测试 [[email protected] ~]# ping 192.168.66.1 PING 192.168.66.1 (192.168.66.1) 56(84) bytes of data. 64 bytes from 192.168.66.1: icmp_seq=1 ttl=64 time=0.261 ms ping nat出口测试 [[email protected] ~]# ping 172.16.20.183 PING 172.16.20.183 (172.16.20.183) 56(84) bytes of data. 64 bytes from 172.16.20.183: icmp_seq=1 ttl=64 time=0.280 ms ping nat外的工作机 [[email protected] ~]# ping 172.16.20.245 PING 172.16.20.245 (172.16.20.245) 56(84) bytes of data. 64 bytes from 172.16.20.245: icmp_seq=1 ttl=63 time=2.39 ms ping 百度DNS [[email protected] ~]# ping 180.76.76.76 PING 180.76.76.76 (180.76.76.76) 56(84) bytes of data. 64 bytes from 180.76.76.76: icmp_seq=1 ttl=52 time=10.2 ping 网易163 [[email protected] ~]# ping www.163.com PING 1stcncloud163.xdwscache.ourwebpic.com (114.80.143.193) 56(84) bytes of data. 64 bytes from 114.80.143.193: icmp_seq=1 ttl=55 time=9.58 ms ping 淘宝网 [[email protected] ~]# ping www.taobao.com PING www.taobao.com.danuoyi.tbcache.com (114.80.174.46) 56(84) bytes of data. 64 bytes from 114.80.174.46: icmp_seq=1 ttl=48 time=8.83 ms
完。。
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