Linux Mail Server Setup and Howto Guide

Red Hat Enterprise Linux 5 and its derivative CentOS 5 includes a graphical tool called Security Level Configuration for configuring the firewall options. This article describes how to use the Security Level Configuration tool to open up the ports necessary for providing an email server.

Firewall Configuration (GUI)

This section describes how to use the Security Level Configuration tool to configure the firewall.

1. Click System, select Administration and click Security Level and Firewall. This will launch the Security Level Configuration window.

2. For a mail server with webmail, check Mail (SMTP), Secure WWW (HTTPS) and WWW (HTTP) in the Trusted services list.

3. We also need to open the ports for the POP3 and IMAP services. In the Other ports field, add the port numbers below.

 

Service

Port

POP3

110:tcp

POP3S

995:tcp

IMAP

143:tcp

IMAPS

993:tcp

Firewall Configuration (TUI)

This section describes how to use the Security Level Configuration text user interface (TUI) tool to configure the firewall.

Launch the Security Level Configuration tool using the command below.

system-config-securitylevel-tui

2. In Security Level Configuration screen, press the Customize button.

3. Open the ports you desire and press OK button when you are done.

You can see the list of service and port numbers by typing in getent services from the Terminal window.

Visit the forum to ask for help or to give a comment.

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Posted on 4/23/2007 and last updated on 8/28/2011
Filed under CentOS 5 , Red Hat Enterprise Linux 5 , System Administration