Have a spare PC gathering dust? Turn it into a multi-purpose server using ZeroShell. Whether there's a real need or you want to do some tinkering around, you ought to find something useful in ZeroShell. Best of all, its Linux-based, open sourced, and free.

ZeroShell is a live CD and doesn't have to be installed. Just pop in the disc and it will boot. You only need a small drive--flash will do--to store the settings.

Here are just some of the features provided by ZeroShell:

• Load balancing and failover for multiple Internet connections.
• RADIUS server for 802.1X authentication, so you can do WPA-Enterprise encryption.
• Captive portal for public hotspot applications.
• QoS (Quality of Service) and traffic shaping features to control traffic flow.
• Wireless access point (AP) mode--soft AP--with multiple SSID and VLAN support.
• VPN server (L2TP/IPsec) to secure local connections, or connect; plus LAN-to-LAN support.

For a complete list, see their website.

Setting up ZeroShell

First things first--gather the hardware. Zeroshell should work well on just about any computer, on typical 32-bit PCs, and higher performance 64-bit machines. An old dusty box loaded with a network adapter or two should be fine. But keep in mind, you'll need at least a Pentium 233MHz processor, 96MB of RAM, and a CD-ROM (ATA) drive, or an ATA Compact Flash (CF) adapter for embedded devices. So you can store your configuration, you'll want some type of storage device, such as a IDE, SATA, or SCSI hard drive; or a external or flash USB drive. All the typical VGA graphic cards and RS232 serial port adapters are supported. Additionally, ZeroShell supports all the Linux-capable PCI, USB and PCMCIA network cards.

If you want to replace your wired or wireless router with ZeroShell, you'll need at least two Ethernet cards loaded in the PC. That way one can plug into the Internet modem and the other to a computer or a switch. To support multiple

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computers on the network without using a switch, try setting up the soft access point (AP) feature. If you want to experiment with its wireless capabilities, throw in a wireless card. You should stick with a Wi-Fi card that uses an Atheros chipset and is supported by the MadWifi drivers. This directory can help you find the chipsets of adapters.

When you're ready to get started, download the CD image (ISO) file from ZeroShell's site and burn it to a CD. Then pop it in the machine you've crafted. Plus make sure you have the machine connected to your router, or directly to the Internet connection, with an Ethernet cable. Once it boots up, you'll see the main command-line menu. The default login credentials and IP address is shown in the upper right corner of the screen.

Before anything, you should change the default password. From the main menu, type P, enter a new password, and hit Enter.

Using ZeroShell along with an existing router

There's two different ways you can integrate ZeroShell into your network. You can either use it to replace an existing router or keep the router and connect the computer to the network. We're first going to discuss the latter, which is easier and still lets you take advantage of other services provided by ZeroShell. This way you don't have to configure the routing and DHCP features of ZeroShell; your existing router can still do those jobs.

In order for ZeroShell to communicate with the network, it must be in the same subnet of the network. By default, ZeroShell assigns itself an IP of 192.168.0.75. Thus if the existing router is in the 192.168.0 subnet (for example, if it has an IP of 192.168.0.1), no further configuration is necessary. However, if the router is in another subnet, you need to change the default IP settings of ZeroShell; here's how: (see page 2)

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