Wireless on Linux, Part 1 - Page 2
August 20, 2003
Adding Wireless to Wired the Cheap and Easy Way
Adding a wireless node to a wired Ethernet is simple, at least in theory: install and configure an access point somewhere on the LAN, next install and configure a wireless NIC on the client machine, and then voilá, you're connected! And sometimes it even works that way.
Newer Linux distributions, such as Red Hat 9, Mandrake 9, Lindows 4, and SuSE 8.1 automatically recognize and install the drivers for wireless NICs. All you have to do is configure the network settings. Lindows has a useful page listing all the wireless NICs that work with it, as well as some that don't; this list should apply to any Linux.
You don't need a lot of fancy folderol; simply buy a Linksys WAP11 for around $90 and a Linksys WMP11 (for desktop PCs) or a WPC11 (for notebooks) for about $60. Plug 'em in, configure them, and away you go.
Of course, there are other brands that work just fine and that are priced right as well. I mention Linksys simply because that is what I'm the most familiar with. All the usual suspects – D-Link, NetGear, SMC – have Linux-compatible 802.11b devices, and any 802.11b WAP that uses browser-based configuration should work with Linux.
In your shopping travels for a wireless base station, you'll see all manner of sleek and kewl devices like the Apple AirPort or the Linksys WAP54G. These are 802.11g wireless access points, which means they work with both 802.11g and 802.11b NICs. Tri-mode wireless access points that support 802.11b, 802.11g, and 802.11a are becoming available as well, as are tri-mode NICs.
These types of WAPs come in a variety of configurations. Some are Ethernet bridges, with user management and security options. Some are routers for sharing broadband connections, and come with firewall capabilities, NAT, and DHCP. Prices for these lower-end WAPs run from $90-$300. The high-end WAPs (the Cisco Aironet 1200, for example) come with more functionality and much better management software, but cost around $600 and up.
A multi-mode access point should make planning for the future a reasonable proposition, but the lack of Linux support makes it a crapshoot. The safest route for the present is to stick with plain ole 802.11b.
Roll Your Own
Because most NICs can be put into "Host AP" (or Host Access Point) mode, you can turn a PC into a sophisticated wireless access point, with all the security, monitoring, and user management you desire. WAPs and NICs contain the exact same chipsets; the only real difference is in the packaging and software.
Most wireless NICs are PCMCIA cards. The ones for desktop machines are stuck onto adapter cards so they fit in PCI slots. And they do look funky. But they work fine.
It's standard now for even the lowest-end devices to come with built-in antennas. It makes a big difference in terms of performance, so don't bother with older devices that do not have one.
WEP: Why Bother?
In terms of built-in security, wireless currently offers WEP (wireless encryption protocol), which comes in various strengths, typically 40-bit and 128-bit. (64-bit is actually 40-bit, and 152-bit is really 128-bit.) The different encryption strengths are not compatible with each other. Given its increasing reputation for being weak, and the silly numbers games vendors play, WEP may not be worth bothering with.
But do not plan to go without some kind of security — your wireless signal is a direct pipeline into your network, an important issue we'll cover in greater detail next week.