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Published on The O'Reilly Network (http://www.oreillynet.com/) http://www.oreillynet.com/pub/a/bsd/2001/04/05/Big_Scary_Daemons.html See this if you're having trouble printing code examples Wireless Networking 04/05/2001 Today I made my wife happy. Yesterday, a 50-foot Ethernet cable ran across the living room floor, under the dining room table, over the gerbil cage, down the cold air return grate, through the basement rafters, and into my basement office hub. Today, it's gone. Instead, a little PC card sticks out two inches or so from the side of the laptop. Here's what you need to know to set up a wireless network in your home or office. First of all, wireless networks are deceptively similar to Ethernet. Both are broadcast media, and can actually interoperate via a bridge. If you're familiar with Ethernet, you're 80% of the way towards getting your wireless network set up. The other 20% is enough to drive you nuts if you don't know what's going on. There's three different standards for wireless communication: HomeRF, Bluetooth, and 802.11b. HomeRF is an older standard. Throughput peaks at 1.6 meg on a good day, with a maximum range of about 150 feet. Bluetooth has been promised for quite some time. It's fast, secure, and reliable. No hardware is actually available yet. (This might change by the time this article is printed.) Since neither hardware nor BSD drivers are available, we don't really care about this right now. 802.11b is more expensive than HomeRF, has considerably greater range, and supports speeds up to 11meg/second. This is the most popular option, and the one with the best FreeBSD support, so we'll cover it here. 802.11b is an IEEE standard, much like classic 802.3 Ethernet. This means that products from different vendors are supposed to work reliably together. There are still few enough vendors that this is basically true; interoperability testing is fairly straightforward. Lucent, Cisco, Apple, and 3Com are the major vendors, while smaller companies like D-Link are just starting to enter the fray. When establishing a wireless system, you need to start up front with some basic decisions about how your setup will work. Do you want to build a separate IP network just for wireless communications, or do you want to bridge your wireless systems into an existing Ethernet? If all the devices on your network are wireless, all you need is a wireless NIC for each machine. Unlike Ethernet, no central hub is required. This is called "ad-hoc" mode. If you want to integrate wireless into an existing network, you need to invest in a wireless access point to bridge between the two. This is "infrastructure" mode. You can use ad-hoc mode in combination with an existing Ethernet, but you can't bridge them together. You would need a router with one wireless interface and one Ethernet interface, and each network needs separate blocks of IP addresses. This might make sense if your network is large enough. Most people are probably interested in infrastructure mode. No company can afford to simultaneously replace all their NICs with wireless ones, let alone discard all their old-fashioned CAT5 network infrastructure. Besides, a wireless network will never run as fast as a physical network. Ethernet relies on "collision detection." Only one packet can be transmitted over an Ethernet at a time. When two machines transmit Ethernet packets simultaneously, this is a collision. Both machines wait