Interest of a firewall

When a computer is connected to the Internet (or to any network), it is a potential target for attacks. Numerous data packets are sent at random by hackers in order to locate machines connected to the network. They look for holes in security in order to exploit them and access the data on the computers.

Thus, it is necessary, in particular for people with an Internet connection (in particular cable or DSL), to protect themselves against intrusions by installing a firewall system. A firewall is a system that allows users to protect a computer from intrusions from the network (or to protect a LAN from attacks from the Internet).

A firewall also allows you to control access to the network by applications installed on the machine. In fact, the trojans are a type of virus that opens a gap in the system to allow remote control of the machine by a hacker. On the one hand, the firewall allows you to locate suspect connections on the machine, but it also allows you to prevent them.

Introduction to ZoneAlarm

ZoneAlarm is a personal firewall (i.e., a program intended for use by individuals) that allows you to protect a machine on a network. Its easy installation and configuration, as well as its high level of protection, make it a reference solution for the protection of personal computers.

This firewall allows you:

• to choose an internet and intranet (LAN) protection level
• to block all traffic (including automatically in stand-by mode)
• to determine which programs will have Internet access
• to determine theIP addresses of the machines authorized to connect
• to receive alerts in case of attempted external connections
• to manage updates

Installation of ZoneAlarm

The program is very easy to install: first, obtain the most recent version of ZoneAlarm:

• Download Zone Alarm

Then, just run the application and follow the installation steps.

Configuring ZoneAlarm

Once ZoneAlarm is installed, just run it (it is activated by default when the computer is booted).

At each first use of an application that attempts to connect to the network (web browser, messaging client, FTP client, etc.) ZoneAlarm will show you an alert asking you whether you wish to authorize the application's access to the Internet.

You are also assured that no information can leave your system without your authorization. The checkbox at the bottom of the page (Remember the answer each time I use this program) allows you not to have to answer more than once for each application.

The Programs tab allows you to adjust the settings for each application:

• A red X means that the application will never be able to connect
• A green checkmark means that the application will always be able to connect
• A black question mark means that ZoneAlarm will request confirmation each time the application attempts to connect.

The Security tab allows you to set the protection levels (Zones): ZoneAlarm defines two zones:

• The Internet zone, which represents remote machines and servers that you do not know, and which you therefore cannot trust. It is recommended to set a high security level for this zone in order to make your machine invisible to hackers.
• The Local zone, which represents machines you trust and to which you authorize access to your shared files and printers. The recommended level of the local zone is Medium.

Add machines to the local zone

It is easy to determine the machines to which you authorize access to your shared folders and printers. To do this, just click on the Advanced button in the Security tab.

By clicking on the Add button, it is possible to add the following:

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

Here is an example of how to add all IP addresses from 10.16.1.1 to 10.16.255.255.