· A firewall while simultaneously being your home website's mail, web and DNS server.
· A router that will use NAT and port forwarding to both protect your home network and have another web server on your home network while sharing the public IP address of your firewall
Originally, the most popular firewall / NAT package running on Linux was ipchains. It had a number of limitations, the primary one being that it ran as a separate program and not as part of the kernel. The Netfilter organization decided to create a new product called iptables in order to rectify this shortcoming. As a result of this, iptables is considered a faster and more secure alternative. iptables has now become the default firewall package installed under RedHat Linux.
Most RedHat Linux software products are available in the RPM format. Downloading and installing RPMs isn’t hard. If you need a refresher, the chapter on RPMs covers how to do this in detail. The latest version of the RPM for RedHat 8.0 is iptables-ipv6-1.2.6a-2.i386.rpm. Install the package using the following command:
[root@bigboy tmp]# rpm -Uvh iptables-ipv6-1.2.6a-2.i386.rpm
Preparing... ########################################### [100%]
1:iptables ########################################### [100%]
Preparing... ########################################### [100%]
1:iptables ########################################### [100%]
[root@bigboy tmp]#
You can start/stop/restart iptables after booting by using the following commands:
[root@bigboy tmp]# /etc/init.d/iptables start
[root@bigboy tmp]# /etc/init.d/iptables stop
[root@bigboy tmp]# /etc/init.d/iptables restart
[root@bigboy tmp]# /etc/init.d/iptables stop
[root@bigboy tmp]# /etc/init.d/iptables restart
To get iptables configured to start at boot:
All packets inspected by iptables pass through a sequence of built-in tables (queues) for processing. Each of these queue is dedicated to a particular type of packet activity and is controlled by an associated packet transformation / filtering chain. Don’t worry if this all seems confusing, there’ll be tables and examples of how the concepts are all interlinked.
For example, the chart and graphic below describe the steps taken by iptables when a packet traverses the firewall.
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