IPTABLES port ing in LINUX

Linux iptables port ing-Linux Enterprise Application-Linux server application information. For details, see the following section. Iptables-a forward-s 0/0-p tcp -- dport 80-j ACCEPT

Iptables-t nat-a prerouting-p tcp-d 218.18.103.114 -- dport 80-j DNAT -- to 192.168.10.100: 80

The preceding command indicates:
For example:
The public IP address of the current Gateway is 218.18.103.114.
The Intranet CIDR block is 192.168.10.0.
There is a WEB server in the Intranet with the IP address 192.168.10.110
So that others can access the WEB server directly through the Internet. Operation Method:
Run the above two lines on the gateway.
When accessing your website, you only need to enter http: // 218.18.103.114/in the address bar to open your internal WEB server and access your webpage.
Other servers and so on:
80 is the WEB server port
21 is the FTP server port
25 is the mail server port
22 is the SSH port
27015 is the CS server port