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
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.
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.
2. In Security Level Configuration
screen, press the Customize
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.
Posted on 4/23/2007 and last updated on 8/28/2011
Filed under CentOS 5 , Red Hat Enterprise Linux 5 , System Administration