iptables实现centos内网机器访问外网

2020-06-16

集群环境描述

外网机器

1
2
3

ubuntu 16.04系统
外网ip 166.111.38.131
内网ip 192.168.11.222

内网机器

1
2
3

centos7.6系统
内网ip1 192.168.11.98
内网ip2 192.168.11.99

实现方法

在带外网的机器上设置iptables规则

1.设置iptables转发规则
iptables -t nat -A POSTROUTING -s 192.168.11.0/24 -j SNAT --to 166.111.38.131
2.在外网机器上打开转发功能
sysctl -a | grep "net.ipv4.ip_forward" #查看是否开启转发规则，值为1为打开
echo "net.ipv4.ip_forward = 1" >/etc/sysctl.conf
sysctl -p #使配置生效

在内网机器上将网关指向外网的内网ip 192.168.11.222

###test1机器
vim /etc/sysconfig/network-scripts/ifcfg-enp33s0f1
TYPE=Ethernet
NAME=enp33s0f1
UUID=04c1412a-f44d-4c09-8c40-44d9716220fc
DEVICE=enp33s0f1
ONBOOT=yes
IPADDR=192.168.11.98
NETMASK=255.255.255.0
GATEWAY=192.168.11.222
DNS1=192.168.11.222
DNS2=8.8.8.8
DNS3=144.144.144.144

systemctl restart network

###test2机器
vim /etc/sysconfig/network-scripts/ifcfg-enp33s0f1
TYPE=Ethernet
NAME=enp33s0f1
UUID=3dae4422-d081-45d7-b359-dfd50bfd87e7
DEVICE=enp33s0f1
ONBOOT=yes
IPADDR=192.168.11.99
NETMASK=255.255.255.0
GATEWAY=192.168.11.222
DNS1=192.168.11.222
DNS2=8.8.8.8
DNS3=144.144.144.144

systemctl restart network

测试

###test1
[root@test1 ~]# ping baidu.com
PING baidu.com (39.156.69.79) 56(84) bytes of data.
64 bytes from 39.156.69.79 (39.156.69.79): icmp_seq=1 ttl=47 time=43.7 ms
64 bytes from 39.156.69.79 (39.156.69.79): icmp_seq=2 ttl=47 time=43.5 ms
64 bytes from 39.156.69.79 (39.156.69.79): icmp_seq=3 ttl=47 time=43.6 ms
64 bytes from 39.156.69.79 (39.156.69.79): icmp_seq=4 ttl=47 time=43.6 ms

###test2
[root@test2 ~]# ping baidu.com
PING baidu.com (220.181.38.148) 56(84) bytes of data.
64 bytes from 220.181.38.148 (220.181.38.148): icmp_seq=1 ttl=46 time=29.9 ms
64 bytes from 220.181.38.148 (220.181.38.148): icmp_seq=2 ttl=46 time=20.5 ms
64 bytes from 220.181.38.148 (220.181.38.148): icmp_seq=3 ttl=46 time=20.0 ms
64 bytes from 220.181.38.148 (220.181.38.148): icmp_seq=4 ttl=46 time=20.1 ms