The Perfect Linux Firewall Part I -- IPCop

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Submitted by evolutionaryit (Contact Author) (Forums) on Tue, 2006-01-17 20:00. :: Security
The Perfect Linux Firewall Part I -- IPCop
Version 2.3
Author: Joseph Guarino
Last edited 02/22/2006

This document describes how to install the GNU/Linux GPL IPCop firewall and create a small home office network. In the second installment we cover creating a DMZ for hosting your own web server or mail server and the Copfilter proxy for filtering web and email traffic.

This is intended to be a quick and dirty overview on creating a IPCop firewall and comes without warranty of any kind!

What is IPCop

The IPCop project is a GNU/GPL project that offers an exceptional feature packed stand alone firewall to the internet community. Its comprehensive web interface, well documented administration guides, and its involved and helpful user/administrative mailing lists make users of any technical capacity feel at home. It goes far beyond a simple ipchains / netfilter implementation available in most Linux distributions and even the firewall feature sets of commercial competitors.

Firewalls have had to undergo a tremendous metamorphosis as a result of evolving threats. IPCop is exemplary in offering such a range of default features and even further a large set of optional plug-ins which can provide further functionality.

Some of IPCops impressive base install features include: secure https web administration GUI, DHCP Server, Proxying (Squid), DNS Proxying, Dynamic DNS, Time Server, Traffic Shaping, Traffic/Systems/Firewall/IDS graphing, Intrusion Detection (Snort), ISDN/ADSL device support and VPN (IPSec/PPTP) functionality. As if these base features were not an astounding enough there are dozens of add-ons which can further expand the functionality of your IPCop from Web Filtering to Anti virus scanning.

Pre-Requisites for Your IPCop
IPCop installation generally runs 25 minutes, and you can complete it with relatively modest hardware requirements such as a 386 processor with 32MB RAM and >300MB of disk, and 3 Network Cards (2 if there is no need for a DMZ). If you plan to utilize caching proxy, IDS or other add-ons, consider additional horsepower in terms of RAM/Processor.

Building Your IPCop What you need
  • 386 Processor with 32MB RAM, 300MB hard disk and 3 Network Cards
  • 2 x 5 port 10/100/1000 switch or a Layer 3 switch
  • Network Cables
  • Burned ISO CD
IPCop Example Network

Architectural Decisions: Segmentation
One essential consideration you have to make before installing is network architecture (segmentation/address space). IPCop uses color-coding system of Red, Green, Blue and Orange to describe the roles or security levels which an interface/network segment will have in protecting your network. Color coding is logical in that it represents a continuum of network access from restricted to permissive. A RED interface is your untrusted interface/segment like the Internet, whereas Green is the trusted interface/segment of your internal network. Additionally, Blue is for a separate segment for Wireless Devices, while Orange is for a DMZ or where any publicly accessible servers you want available to the Internet. In this case we are only configuring a Green/Red/Orange network installation with 3 network interfaces one of which is your cable broadband providers cable modem (Ethernet).

Understanding and Picking your address space

Before you begin it is important to know how your ISP TCP/IP settings. Does your ISP give you a DHCP address or a static IP address? In many cases simply going to your ISP's Support page offers you this information. Most ISPs use DHCP to dynamically allocate IP address space so you get a non-static IP address that applies to your RED interface. Make note of the TCP/IP setting your ISP would have you use before you install.
In architecting your IPCop solution you have the choice of setting up NAT (Network Address Translation) network address space. Green, Blue and Orange networks depend entirely on how many nodes or machines you will have on each network. There are 3 network spaces defined by the standards body, IETF, that can be used for these NAT'ed networks and they are: - (10/8 prefix) - (172.16/12 prefix) - (192.168/16 prefix)

If your Green network contains 15 hosts you can use Your Green interface will run DHCP and pass out addresses to your internal network in this range. The same logic applies to address space on your Orange or DMZ network select a network space appropriate for the number of hosts/networks you will require.

Installing your IPCop

Verify hardware compatibility at IPCop website.
Download the ISO's and burn them.
Connect all the physical layer i.e. Ethernet cables, hook up your monitor, keyboard and mouse to the machine that will be your IPCop
Boot off the CD.
Run through the simple prompt-based installation. NOTE: These are all very self-explanatory steps such as selecting your Language. The arrow Keys, Tab and Enter will help you navigate.

Install Process
  • Select your language.
  • Select your Installation Medium, a CD in this case.
  • Configure your network cards The fastest way to configure your network interface cards is by selecting Probe option. If you know the network card information you can choose to your exact interface from Select.

Next, when you are asked enter your Green Interface an address which must be within your chosen address space (192.168.1.x in our example). Enter in place in the IP address field.

Following this, IPCop will format and copy itself to your hard drive. See below.

After the install has completed you will be prompted to reboot and run setup as shown. See below.

Initial Setup
Having installed IPCop we now have to enter some further configuration information in setup for our setup to be complete.

  • Enter in Keyboard, Time Zone and Hostname/Domain.
  • ISDN Setup As you are not using ISDN you should select to disable it
  • Network Configuration Type - Select the Interface configuration you will be running by tabbing to Network Configuration Type and hit the Enter key.

In our case you would select Red / Orange / Green.

Since we have 3 interfaces and only have set up Green, repeat the interface setup options for the Red and Orange interfaces as described above.
Configure the RED interface to use DHCP as this is interface connected to the Internet (i.e. Your ISP). Then configure your ORANGE interface to use the 192.168.10.x address space. For Red tab over to the DHCP box and select it by hitting Enter. So if your Green network will contain 15 hosts you can use To set this up simply add in this range and tab down to OK.

Password Setup - IPCop has 2 users which you will be asked to setup passwords for the root and admin. Set these both to a strong password > 8 character password that is not a word in any language and contains Caps. A good example would be 1luv19c0p. Root password will be used to log on and add any add-ons or upgrades via SSH. Admin user is used to manage your IPCop day to day.

At the end of the IPCop installation you will be asked to reboot. After reboot go to another machine on your LAN and force your network interface card to update your dynamic (DHCP) address with ifconfig (Linux/Unix) or ipconfig (Windows). Verify you are live and active on the new network you have setup with an address on 192.168.1.x. With this validated connect to secure https web interface of IPCop. Type or and log in as the admin user.

Validate all your settings and connectivity. Then check out all the features you get with this great GNU Open Source Firewall. In the second installment of this how to we will discuss setting up a dynamic DNS, filtering email/web/proxing with Copfilter and allowing access to web/mail server of your choice in the DMZ or orange network. Until then go check out the website & Happy Hacking!!

Evolutionary IT is an independent provider of systems, network and security solutions. Please do feel free to email comments or suggestions Many thanks for the help of my amazing sister Antonina in editing this article.

2006 Licensed under Creative Commons Attribution-NonCommercial_ShareAlike 2.5

Joseph Guarino -- Evolutionary IT --

Please do not use the comment function to ask for help! If you need help, please use our forum.
Comments will be published after administrator approval.
Submitted by access repair (not registered) on Wed, 2011-01-05 08:12.
Although not an official part of IPCop, there are many addons, some based on the addon server, that add additional functionality to IPCop, such as advanced QoS, e-mail virus checking, traffic summary, extended interfaces for controlling the proxy, and many more.
Submitted by iconfly (registered user) on Fri, 2006-11-17 21:51.

This has been a great help to me in the last few days.

Very well written article! 

Submitted by Anonymous (not registered) on Thu, 2006-03-16 13:32.
As far as I remember, IPCop allows any traffic going out from the LAN to the Internet (great for trojans). I wish you could do an article regarding a fix for that.
Submitted by weedguy (registered user) on Mon, 2006-05-08 15:08.

Most firewalls allow connections from the trusted LAN (Green) out to the internet. This can be configured or blocked within IPCop (on CLI w/ IPTABLES) and there are addons to help as well. Check out BOT As I always say one cannot look at a firewall as a panacea but as part of a set of security tool, techniques and processes.



Submitted by Anonymous (not registered) on Thu, 2006-02-09 18:10.
seeing the second part of the article. Ipcop + copfilter = network bliss.
Submitted by Anonymous (not registered) on Thu, 2006-02-02 21:30.

As a user of Ipcop for many years now I have to concur that it is a great gnu firewall.

Submitted by Anonymous (not registered) on Tue, 2006-01-31 21:23.
Great work on the article.
Submitted by weedguy (registered user) on Mon, 2006-02-06 07:41.
Yeah bro its mine too. =)
Submitted by Anonymous (not registered) on Fri, 2006-01-27 22:41.

and am happy to see it getting some coverage and exposure because it is a great GNU/Linux firewall. Everyone should check it out

Submitted by Anonymous (not registered) on Fri, 2006-01-27 15:00.

If you don't want to dedicated a machine as a firewall, Shorewall is great. Excellent documentation. I have been using it for 4 years on my home network.

Submitted by Anonymous (not registered) on Wed, 2006-01-25 16:51.

mybe is better to talk about ipcop addons..... many many

Submitted by Internet_lan (registered user) on Tue, 2006-12-05 02:16.

Good ariticle. In-depth review..

The main difference among other linux firewall is that is its interface is more simple.

Besides, Ipcop firewall has been added to our useful resources.(category firewall).

Best regards,

Sophia Parker

The Directory

Submitted by weedguy (registered user) on Fri, 2006-01-27 17:25.
I just might cover them in the future. =) As I state in the article I will cover my favorite add-on copfilter.
Submitted by Anonymous (not registered) on Fri, 2006-02-03 05:38.

One great addon is the Zerina OpenVPN addon, which is an alternative method of constructing a VPN that is simpler to use than IPSec yet cross-platform. It's based on OpenSSL for secure transport. OpenVPN is regarded as secure, compared to some of the amateur efforts at VPNs in the past like CIPE.

It would be good to cover this and increase the popularity of IPCop and Zerina

Submitted by weedguy (registered user) on Mon, 2006-02-06 07:30.


I do concur. =) Zerina OpenVPN is another amazing IPCop add-on which I hope becomes part of the code base in future releases. Copfilter is another of my favorites which has my vote for inclusion in future releases of IPCop.

Thanks for your comments,

Submitted by Anonymous (not registered) on Mon, 2006-01-23 07:54.

I have been using IPCop for several years now and am very happy about it. This article is very well-written and looking forward to its second part. If both the parts are available togehter in a printer-friendly version, its usfulness would increase.


Submitted by admin (registered user) on Tue, 2006-01-24 12:31.
Below the howto is a "printer friendly" link.
Submitted by weedguy (registered user) on Mon, 2006-02-06 07:35.


There is the link below and these will also be on the Internet Archive in the near future once the second installment is completed. For those of you that do not know about the Internet Archive it is please do check it out at



Submitted by weedguy (registered user) on Fri, 2006-01-27 17:26.
The link will be placed when the series is complete. =)
Submitted by Anonymous (not registered) on Sun, 2006-01-22 00:35.

Good job man! I use IPCop on my own networks and on dozens of clients and I am very happy with it. Keep up the good work IPCop team.

Submitted by Anonymous (not registered) on Fri, 2006-01-20 23:51.
I disagree. I find IPCop to be easy to use and setup but not very extensible. I prefer Clarkconnect

which has many modules and addons and MUCH better community support.


Submitted by weedguy (registered user) on Fri, 2006-01-27 17:39.
Hello Peekj, I have used both as well as the vast majority of commercial firewalls and have ended up sticking with IPCop. For me it does more of what I want and has an amazing support community.
Submitted by Anonymous (not registered) on Mon, 2009-08-10 06:09.
What about other commercial products? have you tried affordable solutions like ideco
i think its functionaly is amazing i think for many companies its more reasonable to employ ready to work solutions rather that figuring out how to use a number of free programs right

Submitted by Anonymous (not registered) on Mon, 2006-01-23 05:37.
The free home version of Clarkconnect may not be that flexible for more demanding tasks? If you want more, don't those Clarkconnect modules and addons often cost money?
Submitted by Anonymous (not registered) on Sat, 2006-01-21 17:46.

Hello Anonimus,

Clarkconnect has 1/2 of the features and many fewer addons than exist for IPCop. The IPCop community has been incredible and I am very happy with the project in every aspect. As well Klarkconnect is not as open and transparent a development community more focused on creating a commercial software NOT a usable free software GPL'd firewall. For this and many other reasons it is a superior Linux firewall.

IPCop Addons

List of IPCop Addons

Submitted by Anonymous (not registered) on Fri, 2006-01-20 08:33.
Good article. I had installed ip-cop long before. Really it is a great free solution. And some add-ons can be applied to ip-cop such as p2p blocking, content filtering and intrusion detection.
Submitted by weedguy (registered user) on Fri, 2006-01-27 17:41.
Thanks so much for your kind words. I hope that you get a chance to check out our second installment.
Submitted by Anonymous (not registered) on Fri, 2006-01-20 02:17.
Thank you for taking the time to write this very helpfull tutorial. I hope you'll also cover using ipcop for vpn access on the next tutorial.
Submitted by weedguy (registered user) on Fri, 2006-01-27 17:28.
I do appreciate your kind words. =) Maybe I will focus on the VPN side of things in a later series.
Submitted by Anonymous (not registered) on Thu, 2006-01-19 22:51.
Just post all of it it would have made for a better read in my opinion. or make both parts available at the same time.
Submitted by Anonymous (not registered) on Thu, 2006-01-19 20:10.

This article is a good intro and it got me going on a FOSS project I did not know about. Good stuff!

Submitted by Anonymous (not registered) on Wed, 2006-02-15 02:25.
I think the invisible firewall feature of pfsense makes it an interesting addition to an IPCop protected network, especially if the tutorial author could persuaded to publish it on
Submitted by weedguy (registered user) on Thu, 2006-02-16 19:22.


Thanks for dropping by. =) Pfsense looks like an interesting project and I am happy to innovation happening in all arenas of free and open source software. My hope is that more firewalls share code and expertise to improve the open firewall options that consumers have.