If you’re looking to build a network and plan on using multiple subnets then you’re going to need a router, without one your network simply won’t work. For each subnet you want your going to need a separate interface whether it is on the same router or on a different one. There are many instances where I have needed to build a quick network consisting of three or four subnets for testing purposes but lacked the equipment to do so.

Multiple interface routers are usually not very cheap (I’m not talking about your average home broadband router by the way!) and the Cisco range are especially on the expensive side when you want several LAN interfaces. You might be able to get a cheap second hand one on EBay but even they can be quite expensive and are usually in poor condition.

The alternative solution – build your own router

This alternative solution is very cheap and can be free in some cases. You will need the following:

  1. An old computer or workstation, the spec can be as low as a 486 with 16mb of ram and this will still work!
  2. Multiple network cards, these can be picked up for very cheap (a few bucks each), you will need one network card for each subnet you want.
  3. A copy of Fresco, the free Linux based router distribution. The software is tiny and fits on a floppy disk so your computer doesn’t even require a CD-drive for this to work. You can download fresco from here.

Step 1 – Prepare the computer

You will need an old computer for this, since the Linux distribution runs off a floppy drive; you won’t require the computer to have a hard drive or a cd-drive. Since you will be using a very low spec machine, the power output will be very low. Ensure you have all the network cards plugged in, you might need to get hold of an additional PCI riser card if you run out of slots for your NIC’s.

Step 2 – Download the Fresco package and copy to floppy.

You can download the latest Fresco release from the sourceforge link below. The zip file contains a batch file which you can run that will make a bootable floppy for you. At this point you’re ready to power on the computer and boot from the floppy disk

Step 3 – Configure Fresco

The Fresco interface is perhaps not the most user friendly in the world since it is Linux based but the functionality is everything you would expect or need. The distribution supports all kinds of networking features including:

  • DHCP server
  • Dial-in server
  • SSH server
  • DNS server

It also supports NAT commands if you want to configure it as a WAN router. A basic configuration will consist of each interface being configured with its respective IP address and subnet mask. Once this is done you will have a basic but fully functioning router that is ready to route packets between all of its subnets. Fresco can also be installed onto a hard drive or USB stick if you wish to do so. There are a whole host of tutorials and guides on the website to help you setup your configuration, there is also a support forum if you get really stuck.

 

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