首先在能上外网的机器上增加一块网卡
我这里两块网卡配置如下
[root@muban1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 外网卡
DEVICE=eth0
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
IPADDR=192.168.56.100
NETMASK=255.255.255.0
GATEWAY=192.168.56.2
DNS1=192.168.56.2
DNS2=223.5.5.5
IPV6INIT=no
USERCTL=no
[root@muban1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 内网卡
DEVICE=eth1
BOOTPROTO=none
ONBOOT=yes
NETMASK=255.255.255.0
TYPE=Ethernet
IPADDR=172.16.1.1
#重启网络服务
service network restart
#编辑内核配置文件，开启转发
vim /etc/sysctl.conf
net.ipv4.ip_forward = 1
#使内核生效
sysctl -p
清空防火墙的filter表
iptables -F
添加转发规则
iptables -t nat -A POSTROUTING -s 172.16.1.0/24 -j MASQUERADE #这里172.16.1.0/24与内网网段对应
其他机器的机器没有上外网功能，只有内网网卡，需要与上面的内网网卡在同一局域网
网卡配置如下
[root@muban2 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth0
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=static
IPADDR=172.16.1.10
NETMASK=255.255.255.0
GATEWAY=172.16.1.1
DNS1=192.168.56.2
DNS2=223.5.5.5
#重启网络服务
service network restart
测试
[root@muban2 ~]# ping 172.16.1.1 -c4
PING 172.16.1.1 (172.16.1.1) 56(84) bytes of data.
64 bytes from 172.16.1.1: icmp_seq=1 ttl=64 time=0.329 ms
64 bytes from 172.16.1.1: icmp_seq=2 ttl=64 time=0.190 ms
64 bytes from 172.16.1.1: icmp_seq=3 ttl=64 time=0.189 ms
64 bytes from 172.16.1.1: icmp_seq=4 ttl=64 time=0.182 ms
--- 172.16.1.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3002ms
rtt min/avg/max/mdev = 0.182/0.222/0.329/0.063 ms
测试2
[root@muban2 ~]# ping www.baidu.com -c4
PING www.a.shifen.com (61.135.169.121) 56(84) bytes of data.
64 bytes from 61.135.169.121: icmp_seq=1 ttl=127 time=11.7 ms
64 bytes from 61.135.169.121: icmp_seq=2 ttl=127 time=32.7 ms
64 bytes from 61.135.169.121: icmp_seq=3 ttl=127 time=9.70 ms
64 bytes from 61.135.169.121: icmp_seq=4 ttl=127 time=9.99 ms
--- www.a.shifen.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3015ms
rtt min/avg/max/mdev = 9.700/16.060/32.761/9.676 ms
到这里，完成！
