Example of opening port 80 in a firewall in Linux

Linux If the firewall is just installed when we commonly used port is not added, that is, can not access, then how to add the common port to the firewall through the state, the following we take 80 port as an example.

Recently I was learning Linux. Build a LNMP environment. Everything is fine during the test. Then restart Linux. Visiting the website again cannot be opened. The final reason is that there are no rules to join port 80 in the firewall. Here's how:

It is very necessary to configure the Iptables firewall under CentOS. Come to us to learn how to configure! , other versions:

1. Open the Iptables configuration file:

The code is as follows	Copy Code
Vi/etc/sysconfig/iptables

by/etc/init.d/iptables Status

The command query has open port 80 if there are no two ways to handle it:

1. Modify the Vi/etc/sysconfig/iptables command to add a firewall open 80 port

The code is as follows	Copy Code
-A rh-firewall-1-input-m state--state new-m tcp-p TCP--dport 80-j ACCEPT

2. Turn off/On/restart the firewall

code such as Under	copy code
/etc/init.d/iptables stop     #start open   #restart restart

After adding the firewall rules as follows:

The code is as follows

Copy Code

# Firewall Configuration written by system-config-firewall  # Manual Customization of the This file was not RECOMMENDED.  *FILTER&NBSP : INPUT accept [0:0]  : FORWARD accept [0:0]  : OUTPUT accept [0:0]  -A input- M state –state Established,related-j accept  -a input-p icmp-j accept  -a input-i lo-j ACCE pt  -a input-m state –state new-m tcp-p TCP –dport 22-j accept  -a input-m state –state new-m tcp-p tcp –dport 80-j accept  -A input-m State –state new-m tcp-p TCP –dport 3306-j accept  -a input-j REJECT –reject-with icmp-host-prohibited  -A Forward-j REJECT –reject-with icmp-host-prohibited  COMMIT /etc/init.d/iptables restart

Add, some friends like to do it

/tbody>

code such as Under	copy code
vi/etc/sysconfig/iptables -a input-m State –state new-m tcp-p TCP –dport 80-j ACCEPT (allow port 80 via firewall)   -a input-m State –state new-m tcp-p TCP –dport 3306-j ACCEPT (Allow port 3306 via firewall)

In this way, the two lines of error are returned when the firewall is restarted.

[Root@localhost ~]#/etc/init.d/iptables Restart
Iptables: Clear Firewall rule: [OK]
Iptables: Set the chain to policy accept:filter [OK]
Iptables: Uninstalling module: [OK]
Iptables: Application firewall rules: Bad argument ' –-state '
Error occurred at Line:11
Try ' iptables-restore-h ' or ' Iptables-restore--help ' for more information.
Failed

Finding this method is not so easy, so try another way to add a port by command.

code as follows	copy code
[root@centos httpd]#/sbin/iptables-i input-p tcp--dport 80-j ACCEPT [root@centos httpd]#/etc/rc.d/init.d/iptables save [root@centos httpd]#/etc/init.d/iptables restart

That's it, look at the effect.

The code is as follows	Copy Code
[Root@centos httpd]#/etc/init.d/iptables Status

Example of opening port 80 in a firewall in Linux