Build It Yourself: A Linux Network Appliance, Part 1

Welcome to our new series on how to build your own Linux-based network appliance. If you’re a small business owner with a shared Internet connection and some networked PCs, this is just what you need to secure your LAN with a powerful, flexible device that outperforms comparable commercial devices for a fraction of the cost, or even no cost at all.

We’ll take you step-by-step through the entire process. You don’t need to be an ace Linux or networking guru. All you need is some experience with computers and to not be afraid to roll up your sleeves and wade in. If you have an old PC lying around you won’t even have to spend any money. Best of all, you’ll understand its inner workings, so you’ll be able to customize it to serve your exact needs.

Why Linux?
You may be wondering why you should use Linux for this project: Because it’s the best tool for the job.

Linux is rock-solid and secure, and it supports the widest range of hardware platforms of any operating system, so you may use whichever one you like: Intel/AMD 32, Intel/AMD 64, Sparc, Apple, Alpha and many more. Linux scales nicely from home offices to small businesses to large enterprises, so it grows as you grow. The value proposition for SOHO use is unbeatable — the software is either free or affordably priced, and chances are you have old hardware lying around that can be recycled for all kinds of useful jobs. If your budget permits new hardware, you might check out low power, quiet, small form-factor computers like the Soekris boards and Mini-ITX.

Even better is the “free as in freedom” aspect. You won’t run afoul of the license police for making copies. You won’t be troubled with expensive server licenses or the Byzantine silliness of per-user/per-seat/concurrent-user/client-access licenses piled on top of the expensive server licenses. Nobody is going force you into “voluntary” compliance audits that you have to buy. You may even modify the source code, though be aware that if you choose to re-distribute it, you need to pay attention to the licensing terms. (See Resources for more information.)

You’ll need two PCs — one connected to the Internet so you can download software and get help, and one to serve as your appliance. Your Internet PC should also have a CD or DVD-writer so you can burn your own Linux installation disks, but if you don’t have this you may order installation disks for a small price. Your appliance PC should meet these minimum requirements:

  • AMD K6, Pentium II or Celeron CPU
  • 64 megabytes of RAM
  • 10-gigabyte hard drive
  • CD or DVD-ROM
  • Two Ethernet cards, different brands that use different drivers

Build a Linux Appliance

  • Part 1: Introduction and Hardware Requirements
  • Part 2: Install and Configure Linux
  • Part 3: The Firewall
  • Part 4: Locking Down the Firewall Box
  • Part 5: Internet Connection Sharing Firewall
  • Part 6: The Firewall

  • Some Linux devotees pride themselves on getting maximum mileage out of very old, feeble hardware, but be assured your geek cred won’t suffer from using more modern, powerful hardware. Newer machines perform better and aren’t as likely to keel over from exhaustion.

    Road Map
    Over the next few weeks, we’ll start with a customized Linux installation to make sure you have exactly what you need. After that we’ll build a nice, solid iptables firewall, then continue with other border services. Then we’ll get into LAN services such as file and print serving, and storage and backups.


    Adapted from, part of the Network.

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