Acacia Free Wireless LAN

This project provides details on how to set up a free public Wireless LAN (WLAN) so that you can share some of your bandwidth with your neighbors.

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Quick Settings

If you are close to Acacia (in Melba, ACT - Australia), you will see a Wireless LAN called AcaciaLTPublicWWW that you can connect to by setting the following:

All that we ask is that you comply with our Acceptable Use Policy and that you email us to tell us your experience with this facility.


Note: this project has been upgraded to the new MegaRouter and this page is currently being updated. FC4 is used for routing between 5 subnets and works really well. Geoff. 4 Apr 06.

The aim of this project is to share spare Internet capacity with others in the local area without exposing the Acacia LAN to the world. This is a major problem with the simplistic approach taken by the WLAN equipment suppliers. It seems so simple to purchase a WLAN base station router, connect it to your ADSL modem and network, and provide roaming access all over your property! The catch is that everyone within radio range also has access to your PCs and data. The firewall in these devices is only designed to protect your network from the Internet, but leaves your LAN fully exposed to anyone within radio range. Don't forget that directional antennas such as used for satellite TV can be used to connect to your WLAN from up to 2 km away.

This project provides all of the details that you will need in order to set up a similar shared access facility.

Although this project looks very straight forward, it took a number of days to get it all functioning. The main difficulty is that all components link together like a chain, and any one setting (like your browser proxy setting) can make it appear that nothing is working. I trust that the steps set out in this project will let you avoid much of this pain.


The Acacia network started off with a single Windows 98 PC, configured with a network card connected to an ADSL modem. As soon as this was working, another NIC was added and connected to an 8 port network hub and from this to a number of other Windows and Linux PCs. Hardware problems with the ADSL modem meant resetting by switching power on and off was needed. Linux with 240V X10 control soon entered the equation, pinging Internet sites and doing an automatic power reset operation as required to retain Internet connectivity.

This configuration is probably typical of many small networks, but note the lack of firewall, proxying and dependence on unreliable Windows systems.

Acacia soon moved to a seperate Linux based firewall (ipchains), and using RP ADSL software. Separate web and mail servers were added.

The first attempt to hook up a WLAN access point quickly revealed the security vulnerabilities noted above and the device was removed. Later, an extra internal firewall was added to isolate the WLAN device into a subnetwork and force all traffic through the main gateway to the Internet. This had problems as many of the LAN facilities such as DHCP, DNS and Web Server had to be exposed from the protected LAN out to the WLAN.

The final iteration of WLAN facilities is described in this project. The installation is based on a "MegaRouter" with 6 network interfaces including:

The "MegaRouter" makes it simple to implement a comprehensive firewall to handle all traffic between all subnets. It also allows any required services to be masqeraded directly at the network interface whilst allowing them to be hosted on any of the subnets.

Physical Configuration

As can be seen in the following diagram, the "MegaRouter" consists of a single Linux server with 6 network ports running iptables firewall. In order to support web access, DHCP, DNS and Squid proxy servers are also installed.


To emulate this public access WLAN configuration, you will need:

And optionally:


In order to implement this project in your own environment, you will need one or more PCs with the following software installed:

Configuration and Testing

This is a fairly complex project, but the following steps should guide you through the process:


Download the wlan_firewall script.

Download the wlan_dhcpd.conf script.

Download the wlan_admcfg.cfg script.


It may be worth reading some of the following links if you are encountering problems:


This is a growing project. Some enhancement ideas include:

Please let me know if you have problems setting this up or you have suggestions or corrections.

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If you would like to get any further information on this or any of the other projects shown on this web site, please send an email to Acacia Lateral Technologies. or place a comment in our Guest Book

You might also like to submit your idea to our Free Ideas page for the benefit of other like-minded soles.