Advantages of a firewall

When a computer is connected to the Internet (or any other network), it is a potential target for attacks. Numerous data packets are randomly sent by hackers to spot connected machines. The latter are looking for a security hole to exploit it and access its data.

As a result, it is necessary, particularly for internet users with an internet connection (particularly cable or ADSL), to protect your computer from network intrusions by installing a firewall system. A firewall is a system that lets you protect a computer from network intrusions (or protect a local area network from Internet attacks).

In addition, a firewall lets you control network access for the applications installed on the machine. Trojan horses are a kind of virus that open a flaw in the system to give a hacker remote control of the machine. A firewall lets you spot suspicious connections on the machine, but it also lets you prevent them.

Introduction to ZoneAlarm

ZoneAlarm is a personal firewall (a software program for private individuals) that makes it possible to protect a networked machine. Its extremely simple installation and configuration as well as its high protection level make it a reference solution for personal computer protection.

This firewall lets you:

• choose an internet and intranet (local area network) protection level
• block all traffic (possibly automatically when in standby mode)
• define programs with Internet access
• define the IP addresses of machines authorized to connect
• receive alerts when outside connection attempts are made
• manage updates

Installing ZoneAlarm

Installing the software is extremely simple: you firstly need to acquire the latest version of ZoneAlarm:

• Download ZoneAlarm

Configuring ZoneAlarm

Once ZoneAlarm is installed, simply execute it (it is activated by default at startup).

Whenever you use an application for the first time that tries to connect to the network (Internet browser, messaging client, FTP client, etc.) ZoneAlarm will present you with a warning asking to you authorize or reject the application's access to the Internet.

You are therefore reassured that no information can leave your system without your authorization. The box you can check at the bottom of the page (Remember the answer each time I use this program) lets you respond only once for each application.

The Programs tab lets you define each application's parameters:

• A red cross means the application can never connect
• A green checkmark means the application can always connect
• A black question mark means ZoneAlarm will ask for confirmation whenever the application tries to connect.

The Security tab lets you define protection levels (called Zones). ZoneAlarm defines two zones:

• The Internet zone representing distant machines and servers you do not know and therefore cannot trust. You are advised to set a high security level for this zone in order to make your machine invisible to hackers.
• The Local zone representing the machines you trust and allow to access your files and shared printers. The recommended level for the local zone is Medium.

Adding machines to the local zone

Defining the machines you allow to access your shared directories and printers is easy. Simply click the Advanced button in the Security tab.

By clicking the Add button, you can add the following items:

• Host/site: a machine identified by its domain name
• IP address: a machine identified by its IP address
• IP range: a group of machines identified by a range of IP addresses
• Subnet: a subnet identified by an IP address and a subnet mask

Here is an example showing how to add the group of IP addresses ranging from 10.16.1.1 to 10.16.255.255.