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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 Tiny Personal Firewall

Tiny Personal Firewall is a personal firewall (i.e., a program intended for use by individuals) that allows you to protect a machine on a network.

Tiny Personal Firewall is free for personal use (professional use must be paid for).

Tiny Personal Firewall supplies a high level of protection, but users will have to have a minimum of knowledge about following protocols TCP/IP. Thus, it is not for beginners. Beginners, however, may make use of a more user-friendly personal firewall such as ZoneAlarm.

This firewall offers three security modes:

• cut me off: which allows you temporarily disconnect your computer from the network.
• ask me first: the software requests the user's input (accept or refuse connection) each time unknown traffic is detected.
• don't bother me: the software lets the unknown traffic through

The Tiny personal firewall also allows:

• protected access to configuration and logs using a password
• remote management of the machine (optional)
• determination of which programs will have Internet access
• creation of a checksum (MD5) for each application. Thus, when an application is modified, the program will notify the user and request confirmation.
• determination of theIP addresses of the machines authorized to connect
• to check access according to time schedules
• alerts in the case of attempted external connections

Tiny Personal Firewall installation

The software is very easy to install: first, obtain the most recent version of Tiny Personal Firewall:

• Download Tiny Personal Firewall

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

After installing, the program will ask you to restart the machine.

Configuring Tiny Personal Firewall

When you run it for the first time after installation, Tiny Personal Firewall will display a screen in which you can choose the action to take.

At each first use of an application that attempts to connect to the network (web browser, messaging client, FTP client, etc.) Tiny Personal Firewall 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 (create appropriate filter rule and don't ask me again) means that you only have to respond once for each application, by defining the local ports involved as well as the destination IP addresses with which the program is authorized to communicate.

Similarly, upon each connection request from a network computer, Tiny Personal Firewall will ask you to authorize or refuse the connection, and to create any filter rules appropriate for each type of connection.

Advanced Tiny Personal Firewall configuration

Tiny Personal Firewall will appear on the Windows taskbar once it is loaded:

A double-click on this icon allows you access to the configuration of Tiny Personal Firewall.
The configuration interface offers the three security modes listed below on its first tab:

• cut me off: which allows you temporarily disconnect your computer from the network.
• ask me first: the software requests the user's input (accept or refuse connection) each time unknown traffic is detected.
• don't bother me: the program lets the unknown traffic through

The second tab (miscellaneous) allows you to set a password for access to configuration and the log.

In the first tab (firewall), the Advanced button gives you access to the advanced configuration of tiny personal firewall.

The advanced configuration of Tiny Personal Firewall offers several tabs:

• Filter rules, which allow you to edit, add, or delete filter rules
• Microsoft Networking, which allows you to specifically set which machines have access to Microsoft sharing
• Miscellaneous, which allows you to manage log access (possibly to a separate server)
• MDF applications, allowing you to check the signing of applications for which there is a rule

Editing filter rules

Tiny Personal Firewall allows you to precisely define the filter rules using the avanced firewall configuration interface:

The interface shows all rules set by the user. Each line represents a filter rule set by:

• A description, accompanied by a symbol
  • This symbol represents an authorized outgoing communication
  • This symbol represents an authorized incoming communication
  • This symbol represents an authorized bidirectional communication
  • This symbol represents an unauthorized outgoing communication
  • This symbol represents an unauthorized incoming communication
  • This symbol represents an unauthorized bidirectional communication
• The protocol(s) involved(UDP, TCP, ICMP, ...)
• The IP address and local port involved
• The IP address and remote port involved
• The application involved

The Add... button allows you to add a rule after the rules already set.
The Insert... button allows you to insert a rule after the selected rule.
The Edit... button allows you to edit the selected rule.
The Delete... button allows you to delete the selected rule.

Editing filter rules

A right-click on the Tiny Personal Firewall item allows you to access the list of open connections in real time.

The green lines represent incoming communications, while the pink lines represent outgoing communications. Finally, the white lines indicate local applications with open ports, i.e., the applications acting as servers, awaiting a connection.

The File menu allows you to start remote administration of a machine. The Logs menu allows you to access the statistics of the firewall system and the logged files.

More information

For more information on firewalls, feel free to consult the page dedicated to the subject. If you have any questions, you can use the CCM forum.

Here is a list of additional sites on the subject:

• The editor's page
• Firewall-net
• The Wanadoo cable security page

Article by Jean-François PILLOU