Port ing of iptables in CentOS

I. environment and requirements lab environment node network settings are as follows: node nic ip node Node1eth0172.19.104.33 intranet No I. environment and requirements lab environment

The network settings of the node are as follows:

Node	Nic	IP	Network
Node1	Eth0	172.19.104.33	Intranet
Node1	Eth1	6.6.5.5	Internet
Node2	Eth0	172.19.104.14	Intranet

Requirement

The function we need to implement is to map Port 8100 of Node1 to port 8000 of Node2, that is, access http: // 6.6.5.5: 8100 over the internet to access the WEB service on port 8000 of PC2.

II. implementation steps

The following operations are performed on node1. some modifications may require the root permission.

1. Edit/etc/sysctl.confConfiguration filenet.ipv4.ip_forward = 1The default value is 0. run the command again.sysctl -pMake it take effect

Or directly execute

echo 1 > /proc/sys/net/ipv4/ip_forward

2. execute

iptables -t nat -A PREROUTING -d 172.19.104.33 -p tcp --dport 8100 -j DNAT --to-destination 172.19.104.14:8000iptables -t nat -A POSTROUTING -d172.19.104.14 -p tcp --dport 8000 -j SNAT --to 172.19.104.33 iptables -A FORWARD -o eth0 -d172.19.104.14 -p tcp --dport 8000 -j ACCEPTiptables -A FORWARD -i eth0 -s 172.19.104.14 -p tcp --sport 8000 -j ACCEPTiptables save 

Note the IP address, port, and Nic configurations.

Or directly modify the location file

Edit/etc/sysconfig/iptables AddThe following content:

The following is a reference file, which can be modified according to the actual situation.

...-A PREROUTING -d 172.19.104.33 -p tcp -m tcp --dport 8100 -j DNAT --to-destination 172.19.104.14:8000-A POSTROUTING -d 172.19.104.14 -p tcp -m tcp --dport 8000 -j SNAT --to-source 172.19.104.33...-A FORWARD -o eth0 -d 172.19.104.14 -p tcp --dport 8000 -j ACCEPT-A FORWARD -i eth0 -s 172.19.104.14 -p tcp --dport 8000 -j ACCEPT...

3. restart iptables.

/etc/init.d/iptables restart  

Or

service iptables restart

III. test

Access http: // 6.6.5.5: 8100 to access the WEB service on port 8000 of Node2.