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Question :

I’ve Redhat Enterprise Linux 5 server with Iptabeles firewall enabled. By default it is only allowing port 22. How do I open port 80 / 143 / 110 on Linux? I’ve started all services but don’t know how to open port using iptables.

Answer :

By default iptables firewall stores its configuration at /etc/sysconfig/iptables file. You need to edit this file and add rules to open port number. This file only avilable under Red Hat Enterprise Linux 3/4/5 and above

Open port 80

Open flle /etc/sysconfig/iptables :

vi /etc/sysconfig/iptables

Append rule as follows :

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT

Save and close the file. Restart iptables :

/etc/init.d/iptables restart

Open port 110

Append rule as follows :

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 110 -j ACCEPT

Open port 143

Append rule as follows :

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 143 -j ACCEPT

Restart iptables service. Type the following command :

service iptables restart

Verify that port is open. Run following command :

netstat -tulpn | less

Make sure iptables is allowing port 80/110/143 connections :

iptables -L -n

Refer to iptables man page for more information about iptables usage and syntax :

man iptables

Sumber:
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