DIY wireless networking - Part 2

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Wireless Lans come in all shapes and sizes, with a vast range of products to suit all requirements and budgets. These range from deploying an entire wireless corporate intranet to simply connecting two PCs without trailing a cable up the landing.

In between there are numerous solutions for wirelessly sharing an internet connection throughout your home, office, or in a public environment.

What products do you need?

Whatever your requirements, building a wireless network is very simple because they consist of only two types of products: wireless network adaptors and Waps.

All devices that connect to a wireless network need to be equipped with wireless adaptors. They're available with a variety of interfaces including USB, PCI, PC Cards and even Compact Flash (CF) cards; typically their antennas will either be a short stick or a bulge on the end of a card.

An increasing number of notebooks, tablets and even some PDAs come with built-in wireless adaptors as standard, and the long-term plan (kicked off by Intel's new Centrino technology) is to integrate wireless directly onto notebook and desktop motherboards.

A pair of wireless adaptors can communicate directly with each other in what's called an 'ad-hoc' network - this is effectively the wireless equivalent of connecting two machines with a single cable.

Both machines can then share each other's files, resources (printers or internet connections etc), run messaging applications and play network games.

More sophisticated and flexible are 'infrastructure' networks, where all wireless clients connect to the main network and its resources through a Wap. The Wap works like a wireless hub and can support multiple wireless clients simultaneously - 20 to 60 depending on the model.

Waps are fairly simple devices, essentially a small box with antennas at one end and an Ethernet port at the other. Connect one to your network hub and you're ready to share its resources with any wireless adaptor in range.

As explained earlier, both the Wap and adaptors need to be using compatible 802.11 systems to work together. Now we'll look at the equipment and costs of four typical wireless environments.

Networking two PCs

Networking a couple of PCs allows them to share files, printers and internet connections, along with playing games. While you could simply connect an Ethernet port in each with a single cross-over cable, laying the wire itself could be undesirable or even impossible.

Wireless networking can connect the two machines without a cable in sight. Simply equip both machines, be they desktops, notebooks or one of each, with a wireless adaptor and tell the supplied software that it is on an ad-hoc network.

he adaptors will then automatically go looking for each other and, so long as they're within range, your network is finished.

Pairs of basic 802.11b adaptors cost from £90 ex VAT and, if they're from the same company, Wi-Fi certification isn't essential.

Sharing broadband

If you have more than two computers or don't fancy leaving one switched on just in order to share an internet connection, then a router and Wap should form the heart of your network.

This set-up makes particular sense if you're using broadband, which is an always-on connection.

A router can automatically share your broadband internet connection and many models also include a hub with four network sockets, allowing you to connect any combination of PCs, Macs, notebooks, or even suitably equipped games consoles like the Xbox.

Not only will the router allow all connected devices to share your broadband, but the hub will let them exchange files and share other resources such as printers.

Some routers even include built-in ADSL modems from just £100 ex VAT, which is great news for new ADSL self-install customers who would have to buy their own modem for at least £50 anyway.

For wireless access, simply connect a Wap to the router (from around £85 ex VAT), or buy a router with a built-in Wap (from around £100 ex VAT).

A well-placed Wap could deliver wireless access throughout an entire home. One of the most integrated devices we've seen so far is Netgear's DG824M, which features an ADSL modem, broadband router, four-port Ethernet switch and built-in 802.11b Wap, all for £213 ex VAT.

The advantage of going for a separate Wap, though, is the ability to easily locate it high on a wall or swap it entirely for a faster 802.11 standard in the future. Having said that, most wireless routers can have separate antennas attached for easier positioning.

Additionally, since most broadband connections are between 1.5 and 2Mbps, the 11Mbps bandwidth of 802.11b is more than sufficient for sharing them wirelessly.

In terms of networking, 802.11b is also sufficiently quick for most home and small office requirements. Congestion on the 2.4GHz band and a maximum of around 20 wireless users per Wap also shouldn't be a problem for most installations.

If you want to transfer files faster, or perhaps stream high-quality video between your machines, then 802.11g should be considered.

It's unlikely to match the performance of 802.11a when many wireless clients are connected simultaneously, but most homes will have less than five, and it's likely to be a cheaper technology too.

One of 802.11g's major benefits could also be its Achilles' heel. Backwards compatibility with 802.11b sounds great in theory, but just one 802.11b client might force an 802.11g network to operate at 11Mbps.

We've only tested one pair of 802.11g products so far and, while we were impressed, more cautious users would be advised to wait until the standard becomes officially ratified later this year.

Deploying wireless networks In theory, deploying wireless access in a larger company is exactly the same as in the home. To get started you simply connect a Wap to the existing network and equip clients with compatible adaptors.

In practice, though, greater numbers of users, larger offices, stricter security and radio congestion all play an important role.

A budget Wap might only support fewer than 20 clients and deliver reduced performance over longer distances. While additional Waps can increase both the range and numbers of users, investing in higher-quality models from the outset is a better plan.

Models like 3Com's Access Point 6000 may cost three times the price of a budget 802.11b Wap, but deliver better performance over a longer range to more users, while also offering superior security.

A site survey is essential when deploying wireless in any business environment, and may reveal a number of potentially conflicting 802.11b networks nearby.

If congestion becomes an issue, then switching to the higher 5GHz frequency of 802.11a is the answer. Since it and 802.11b operate independently, a business can expand with a dual-mode access point delivering uncompromised support to clients of either standard.

Products such as Orinoco's AP-2500 (£485 ex VAT) come with 802.11b support as standard, but can take an 802.11a card later to expand. 802.11a PC Cards currently cost around £99 ex VAT - double that of 802.11b cards.

Finally, you should always carefully consider if wireless really is the best solution. Cabled networks are cheaper, faster and inherently more secure. If you can lay cables, we'd recommend doing so.

Using public hotspots

An increasing number of wireless networks are being built in public places such as cafes, airports, train stations, hotels or even entire urban city centres. These networks deliver broadband internet access to any wireless devices in range, either free of charge or in return for a subscription or one-off payment.

In order to be compatible with the largest installed based of wireless equipment, all public hotspots so far use 802.11b technology. If your device does not have 802.11b facilities built in, you'll need to equip it with an 802.11b adaptor, although an 802.11g or dual-mode adaptor should also do the trick.

If you're relying on accessing many different public hotspots, we'd advise fitting your portable with a Wi-Fi-certified adaptor to minimise potential incompatibilities, such as 3Com's Office Connect PC Card at £59 ex VAT - this will also obviously work on a home or office 802.11b network and, since it's an international standard, you'll also be able to use hotspots anywhere in the world.

BT is rolling out hotspots throughout the UK and its Openzone programme intends to have 400 public hotspots by June 2003; see www.bt.com/openzone.

Wireless security

Security is an essential part of wireless networking, as there's nothing stopping the radio waves penetrating the exterior walls of your home or office.

Indeed many wireless networks have been hacked by snoopers outside the building, while so-called war-chalkers mark areas where they've discovered unsecured wireless internet access.

When you look at it this way, the shorter range of 802.11a begins to look like a benefit, while the line-of-sight requirement of infrared becomes the ultimate security precaution.

If a wireless network has no security, the only piece of information required to connect is its Service Set Identifier (SSID) name.

SSIDs are normally broadcast by wireless devices and can be easily picked up by snooping utilities such as Netstumbler; Windows XP can even do the snooping for you with its option to list all the available SSIDs within range and automatically connect.

Fortunately a security protocol was defined as part of the 802.11b standard: Wired Equivalent Privacy (Wep) encrypts data at one end and decrypts it at the other in conjunction with a secret key which can be either 64 or 128bits in strength; these are sometimes called 40 and 104bit respectively.

To secure your network, simply activate Wep on the access point and provide the passkey to authorised users only.

As our results in the main feature show, activating Wep slightly reduces overall speeds, but unless you live miles from another wireless network or don't care about your data, we'd recommend using it.

Paranoid corporates should, however, watch out for rogue access points connected to their network without Wep, thereby providing security-free wireless access either intentionally or otherwise.

That said, Wep has been proven to be less secure than its developers hoped, and towards the end of 2003 it will be replaced by a more robust system, currently known as 802.11i.

Interestingly the Wi-Fi Alliance has already taken a subset of this to produce an interim solution called Wi-Fi Protected Access, and there should be updates available for most existing Wi-Fi products.