Firewalls

Definition from Intel
A firewall is a system that secures a network, shielding it from access by unauthorized users. Firewalls can be implemented in software, hardware or a combination of both. In addition to preventing unrestricted access into a network, a firewall can also restrict data from flowing out of a network.

Types of Firewalls

• Software firewalls – program based
• Hardware routers – a physical hardware box such as an internet router
• Wireless routers – a hardware box using wireless connectivity

In Simplistic Terms

Typically, an internet firewall is a hardware device (router) represented by a series of doors, on a physical wall, between your computer network and the internet.  These doors are either open or closed, depending on your settings.
On the outside of this wall, on the internet side, is a single address, similar to your house address. This is your
IP address and like your house, no two addresses, in the world, are the same.  This is so your mail, internet programs and visitors can find your network.  You can find this address by going on the internet and going to http://www.whatismyip.com/ .

The first step is to lock all unnecessary doors or ports.

Every internet access process has a nominated reserved port or door at which it will attempt to gain access to your network, through your router.  e.g. RDP – 3389, PCAnywhere – 5631 and 5632, Internet – 80 etc.

Examples of access processes
If you wish to take control of your computer from home

Windows uses a process called RDP (Remote Desktop Protocol).
In Windows XP, it can be found under Start/ All Programs/ Accessories/ Communications/ Remote Desktop Connection.
When you select this, you get the following window.

Diagram 1.

By putting in your work IP address (see how to find above) at where it says “Computer”, your home computer sends a process, out on the internet, knocking on door (port) 3389 on your router at work.   If you have anticipated this and put in the appropriate settings, door 3389 will open and lead the process (from your home computer) to the internal address of your work computer, giving you its login screen.  tycoordinator.aspx" id="MMMenu0630134824_1_Item_1" class="MMMIVStyleMMMenu0630134824_1" onmouseover="MM_menuOverMenuItem('MMMenu0630134824_1');"> Security Coordinator Details Security Policies and Training Access Control Procedures Anti-Virus Procedures Anti-Spyware Procedures Firewall Details Disaster Recovery Procedures Consulting Room & Front Desk Policies & Procedures Backup Procedures Network Maintenance Software Library Micellaneous Create PDF Doc