This article will describe in depth how to configure and run Firestarter under Linux. It is broken into three sections: introduction and installation, first running and loading Firestarter at boot time.

I – Introduction

II – First running

In order to run, Firestarter, click on System -> Administration Tools -> Firestarter.

At the first running, a wizard will help you to configure Firestarter by choosing the monitoring interface (it will automatically detect any active interface). If your IP address was assigned by Dynamic Host Control Protocol (DHCP), you should tick the corresponding option.

The second dialog box will prompt you to share your Internet connection and use your computer as a DHCP server.
If your computer is directly connected to the Internet and share it with other computers on the same network, tick the 2 cases or click on Next and Save to quit the wizard.

If you install another network connection later on, you should (especially if the Firewall block your connection) run the wizard again by clicking on Firewall -> Run Wizard. For experts, it is also possible to use Edit -> Preferences.

II- 1 The Status Widget

This widget shows you the status of the firewall. It also helps you to monitor it. The status of the firewall could be one of the following:

1. Working: this means that the firewall is currently working so everything is ok
2. Stop: the firewall is idle so it is not interfering on the network traffic
3. Blocking: The firewall is currently blocking every incoming and outcoming connection. This also means that no data are currently moving on the network.
   

II – 2 The event widget

1. Black: Regular connection on a port but blocked by the firewall. So you should not worry.
2. Red: Likely intrusion entry but bloked by the firewall
3. Gray: Good broadcasting connections according to Firestarter
   

All these are illustrated at the next picture.

II – 3 The Policy Widget

This is where you should define for rules for your incoming and outcoming connections. For outcoming connections, I advise you to use the default option. For incoming connections, if you have some servers running on your computer, you should open their corresponding ports

1. Right click in the area “Allow a service”
2. “Add a rule”
3. Select in the list the name of service you would like to run for instance FTP for an FTP server  
4. In the source field, you should leave the default option in order to open the port for everybody.  
5. Finally you should click on Add

II – 4 Preferences

Default preferences will suit the user lambda. Those who already know some knowledge of network protocols and firewalling will not spend an awful amount of time to learn about it. For those who do not have enough skills, they should look at online references, Google is their friend.

III – Loading Firestarter at boot time

Although Firestarter is a good software, it is sometimes tricky to run it at the beginning of the session. Indeed, when you try to add Firestarter in System -> Preferences -> Sessions, you immediately have an error message saying that the eth0 interface is not available. This is due to that the interface will be started at the same time as the network.

The first thing you should do is to allow Firestarter to run:

$ su visudo

Append the line:

username ALL= NOPASSWD: /usr/sbin/firestarter

Warning: Do not forget to replace the username will your actual one!
Now you should create a blank file called .start_firestarter

$touch .start_firestarter

Edit the file.

gedit .start_firestarter

Copy the following information
With 2 network interfaces eth0 (wi-fi) and eth1 (LAN)

#! /bin/bash

verif=$(ifconfig eth0 | grep Octets | cut -d: -f2 | cut -d' ' -f1)
verif1=$(ifconfig eth1 | grep Octets | cut -d: -f2 | cut -d' ' -f1)
i="0"

while [ "$verif" -lt 900 ] && [ "$verif1" -lt 900 ] && [ "$i" -lt 100001 ]; do
verif=$(ifconfig eth0 | grep Octets | cut -d: -f3 | cut -d' ' -f1)
verif1=$(ifconfig eth1 | grep Octets | cut -d: -f2 | cut -d' ' -f1)
let $[ i=i+1 ]
done

if [ "$i" -lt 100000 ] ; then
{
sudo firestarter --start-hidden
}
fi

exit 0

With only 1 interface

#! /bin/bash

## Get the number of octects received on ethO
verif=$(ifconfig eth0 | grep Octets | cut -d: -f2 | cut -d' ' -f1)

## counter

i="0"
## Tif the network card is yet to receive 900 bytes or the counter is not finished
while [ "$verif" -lt 900 ] && [ "$verif1" -lt 900 ]; do
verif=$(ifconfig eth0 | grep Octets | cut -d: -f3 | cut -d' ' -f1)
let $[ i=i+1 ]
done

## if the loop is not finished before the counter, then Firestarter is run in the task bar
if [ "$i" -lt 100000 ] ; then
{
sudo firestarter --start-hidden
}
fi

exit 0

Now to end up everything, you should go to System -> Preferences -> Sessions and add:
Name : firestarter
command: sh /home/<<username>>/.start_firestarter

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