You asked for it, it's the: ## # ## ##### ## ##### ##### ## ## ### # # # ## # # # # # # # # # # # # # # #### # ### #### # # # ### ## ## # # # # # # #### # ## ##### # Last updated: 3/30/03 By -> Rob Flickenger and Adam Flaherty (and a cast of thousands) Get it at -> http://nocat.net/faq.txt Version: 1.02 (c) 2001 Rob Flickenger Publish, disseminate, use at will, just don't change it or claim you wrote it. Send updates to faq (at) nocat (dot) net, and they'll be incorporated into the master copy, with full credit to you. This is a work in progress. It's probably entirely untrue, libelous, and blasphemous. Use at your own risk. Have fun. ~~~~~ Who we are ~~~~~~~~~~ A smallish (50 or so) community group in western Sonoma County, CA trying to get a free access wireless network together. We do this on our own time, for no pay, fronting costs, promoting, developing software, trying hardware, and pulling together group hardware discounts wherever possible. There is probably a group like us near you! If not, start one yourself! I guarantee you won't be bored! This FAQ was banged out in a couple of days, and will likely metamorphosize as time goes on. Send additions, corrections, and ideas to faq (at) nocat (dot) net. ~~~~~ Table of contents ~~~~~~~~~~~~~~~~~ General questions Q: 802.11b? 802.11? 802.11a? Bluetooth? Ricochet? CDMA? FHSS? DSSS? What's it all about? Q: What does it take to set it up? Q: How fast is it? Q: How far can it go? Q: Can I get rid of my DSL/Cable connection? Q: I've read that wireless networks are just backdoors into my wired LAN. Is this true? Should I be afraid of 3l33t w@rDrIv3rZ 0wning my net???!?! Hardware questions Q: Will a 'Brand X' wireless card work? Q: How do I upgrade when something faster comes along? Q: What's LMR-200? 400? 600? Why is this cable so thick and expensive? Q: What's a BNC/SMA/N/UHF connector? Q: What's a Pigtail? Antenna questions Q: What kind of antenna do you use? Q: Do I have to use an antenna from the same manufacturer that made my card? Q: Do I need the same kind of antenna on both sides of a link? Q: What are the frequencies that 802.11b uses? Q: Where can I get an antenna? Q: What about amps? Q: Is it legal? Specific applications Q: Can I hookup my classroom / office / house? Q: Can I use 802.11b to unplug my Desktop machines, so I don't need yards of CAT5 running around the house? Q: Can I setup a point to point link to get internet access to somewhere that can't otherwise get it? Community network questions Q: Why would I bother setting up community access to a service I'm paying good money for? Q: How can I provide community access over my local internet connection? Glossary ~~~~~ Q: 802.11b? 802.11? 802.11a? Bluetooth? Ricochet? CDMA? FHSS? DSSS? What's it all about? A: Right now, there are probably dozens of competing wireless technologies, all with different capabilities, requirements, and implementation goals. Some (like Ricochet and CDMA phone networks) are commercial, pay-per-use services. Others, like Bluetooth and 802.11a, allow for easy, one time cost network connections, but aren't quite ready for prime time (as of this writing.) The NoCat Community LAN project, like many popping up around the world, has decided to (at least initially) standardize on 802.11b as a method for getting people connected to the Internet, due to its very low cost and increasing ubiquity. Any product that is truly 802.11b compliant can communicate with any other, regardless of platform or operating system, without requiring a Telco or other information carrier. Support for 802.11b is available for laptops, desktops, handhelds (like the Compaq iPAQ and the Handspring Visor), and nearly any device that has a PCMCIA slot. Manufacturers like Apple, IBM, Dell, and Compaq are integrating 802.11b into the design of their portable PCS, bringing wireless access and computing power into a single package. This FAQ specifically tries to answer basic questions about 802.11b wireless networking. See the Glossary at the end for some definitions of other wireless technologies. ~~~~~ Q: What does it take to set it up? A: It depends on what you want it to do. If you want to access an existing wireless network (like NoCat or your local community network, or the wireless network at your office or a conference) you need a card capable of talking 802.11b. These are usually PCMCIA devices, but USB, PCI, Ethernet, Springboard, and even serial radios are available. This usually plugs into a laptop, desktop, or handheld computer to let you access the local wireless network. Total cost: $50-$300, depending on the radio. If you want to repeat your house LAN over wireless (so that you don't need to plug in your laptop to access the Net) then you'll also need a device called an Access Point (which lets the Wire and your Wireless gear talk to each other). Total cost: between $300 - $500, depending on the gear you choose. See the discussion below on APs, Cards, and what they are capable of. Keep in mind that in addition to the AP, each of your client machines (i.e., laptops) will need a radio card as well. If you want to setup a long distance point-to-point link, you'll either need two APs that can talk to each other over the air, or a PC and an access point, or two PCs and two radio cards, plus antennas and cabling. Total cost: probably $500 to $2000 or more (depending on how much you're willing to make for yourself.) That would get a wireless link going to a single point, several miles away. If you want to provide access to a large group of people, you have several options: roll your own, use one or several low end access points, or buy high end commercial POP gear. The commercial stuff can run upwards of $20,000 (if you think you want to become a WISP, this is the stuff for you.) Networks supporting several hundred people have been built for less than $2000. See below for examples on how to do this. If you want to setup a cooperative of wireless gateways for community access, you're not alone. Check out the nearly infamous wireless community list at http://www.toaster.net/wireless/community.html. Also see the discussion below about active portals and free access wireless gateways. ~~~~~ Q: How fast is it? A: It depends. The card manufacturers would like you to believe that you could get 11Mbs. That is the raw radio rate, not the effective data rate. Due to the overhead of the 802.11b protocol, plus TCP/IP, your best throughput will top out around 6.5Mbps (with nobody else using the same channel.) Note that this is about comparable to traditional 10baseT wired ethernet. As you move further from an access point, your radio will reduce the data rate to get a better signal at a distance. Most 802.11b gear supports data rates of 11, 5.5, 2, and 1Mbps. The slower you go, the further you can stray from the AP. Other factors (people on the same network, noise, bad line of sight to your access point) can also bring the speed down a bit. But in most circumstances, it's FAST. ~~~~~ Q: How far can it go? A: Depends on how fast you want to talk; see above. With no external antennas, the typical indoor AP range is listed around 25 meters at 11Mbps, and 50 meters at 1Mbps. Outdoor, with unobstructed line of sight is typically quoted at 150 meters at 11Mbps, 500 meters at 1Mbps. These figures vary wildly, depending on the radio output power (see below), environmental noise (such as 2Ghz cordless phones, Microwave ovens, X10 gear, older 802.11 networks, Bluetooth), and intervening walls and other obstructions that absorb or reflect microwaves (like brick, concrete, metal, and trees). On long distance links, weather can cause additional signal loss as well. Adding appropriate antennas, with good line of sight, can extend the range of typical client cards for several miles. Even a small external antenna on your client PC can make a huge difference in communications range. Point to multipoint links of half a mile or more are not uncommon. Point to point links of five miles or more are straightforward to setup, with the proper antennas. In the NoCat network we have three 11 mile links with a 16 dbi sector antenna at one end and a 24 dbi sector at the other end. These are operating just fine at 11 mbps speeds. ~~~~~ Q: Can I get rid of my DSL/Cable connection? A: Maybe, but probably not. If you want to talk to the Internet, your traffic has to hit a land line at some point. There's no way to get around this. Wireless bandwidth may be free (cost of equipment), but Internet bandwidth costs money. If you are looking to offset the cost of that fancy new DSL/Cable connection you could always get a few friends and neighbors together and share the cost between everyone, but be aware that you do so at your own risk. Be sure that your ISP allows for this sort of arrangement. Most seem to have no trouble with sharing a connection, but take offense at reselling for profit. Others (notably Cable Modem providers) actively seek out and shut down people who violate their one user per account agreement. In short, make sure it's legal with your ISP before setting up anything, and only choose ISPs that allow fair use of their service! If you can't get high speed access where you are (if you are geographically or politically isolated, for example), and you have line of sight to someone who can, you may be able to setup a point-to-point link and share your neighbor's line. Contact them directly and see what you can work out. We can give you technical pointers, but you're the one who has to introduce yourself. If you're particularly ambitious (like Seattle Wireless or the Personal Telco Project (see references)) you may be able to help setup a parallel wireless network where most nodes don't use an ISP at all. Take a look at their great sites to see how this is being done. NoCat's immediate goal is to provide fair (and safe) internet line sharing to the local community. This requires high speed net access at each wireless gateway. If you want to be a NoCat node, you'll need to provide internet access somehow (either through DSL or other high speed connection, or over a wireless backbone to another node.) ~~~~~ Q: I've read that wireless networks are just backdoors into my wired LAN. Is this true? Should I be afraid of 3l33t w@rDrIv3rZ 0wning my net???!?! A: It's possible to setup any network insecurely. The freedom that wireless gives you also could expose you to unwanted access. It's also possible to write your PIN number on the back of your ATM card, and leave it in a public phone booth, or keep your house key under the welcome mat. It is now generally considered a bad idea to rely only on builtin wireless security features (like WEP encryption and closed networks) to keep your wired net secure. It's widely regarded as a good idea to put your wireless services outside of your firewall, so that in the worst possible case, an intruder would still gain little more than Internet access. If you're interested in setting up open access to your network, many people are working on ways to do it so that bandwidth use is fair and discourages abuse. One simple way to lock down a gateway would be to connect your AP over ethernet directly to a firewall that only allows access to ports 80 (http), 443 (SSL), and maybe 22 (ssh) and 1723 (MS VPN). You could further use throttling rules to limit the total available bandwidth to the wireless users. Alternatively, only allowing ssh and VPN access would ensure that people would have to authenticate themselves to a machine SOMEWHERE before getting further access. The details of these kinds of rules and methods for making them happen are still in flux. Hopefully a general consensus can be reached in the near future. In the meantime, feel free to experiment! Check out the Advanced Routing HOWTO and Firewall HOWTO, both at the LDP (http://www.linuxdoc.org). ~~~~~ Hardware Questions ~~~~~~~~~~~~~~~~~~ Q: Will a 'Brand X' wireless card work? A: The standard NoCat is currently using is IEEE 802.11b. The short answer is: if it's 802.11b then it will probably work. See the Card List for more specific information. We don't use WEP encryption, so don't worry about what level your card does or doesn't support. If you want to use WEP (like on a point to point link, or at your home or office) then be sure that all cards in the system support it. The 802.11b standard defines 40bit WEP encryption. Anything beyond that is manufacturer specific, and isn't guaranteed to interoperate. Even WEP can be dicey, as some manufacturers have taken liberties with interpreting how to do it. Don't rely on WEP to keep your network secure anyway, as it's been proven to be less than impenetrable. ~~~~~ Q: How do I upgrade when something faster comes along? A: New technology is constantly in development and we are always evaluating what is available. Having the radio on PCMCIA does help when wanting to upgrade your system. However, the newer 802.11a cards are likely to be CardBus cards, so your funky old 486 laptop may not cut it (unless it has CardBus support, and even then will probably have trouble keeping up with the higher data rates.) Consider this question, though: What is your reason for wanting to upgrade? If you want faster internet access, keep in mind that the vast majority of websites are still at speeds of 1.5Mbit or less, and are designed to support users on 56k modems. Having a 56Mbit wireless connection will generally do you no good if there's net congestion upstream. As faster wireless technologies emerge, we're certainly going to look into using them to boost backbone speeds and support fast connections to local servers. But 802.11b will likely be with us for quite a while, as it is so cheap, so ubiquitous, and still so much faster than most Internet connections. ~~~~~ Q: What's LMR-200? 400? 600? Why is this cable so thick and expensive? A: LMR is a kind of coax cable made by Times Microwave. All cable introduces some loss as signal travels through it. LMR is designed to have lower loss at microwave frequencies than other types of coax. It uses a braided outer shield and solid center conductor. Heliax is another kind of cabling made by Andrew (http://www.andrew.com). It is made of a semi-rigid corrugated outer shell that borders on copper tubing, rather than the braided strands found in coax. The center conductor can either be solid or a corrugated tube inner conductor. It is designed to handle loads MUCH greater than (legal) 802.11b installations, is very expensive, and difficult to work with. It is also extremely low loss. The foam dialectric type part numbers start with LDF. Don't mess with air dialectric unless you enjoy the challenge of keeping your feed lines pressurized with liquid nitrogen... ;) Belden also makes a couple of popular pieces of cable that work okay in the 2.4Ghz range, 9913 and 9914. Generally speaking, the thicker and better built the cable, the lower the loss (and the higher the cost). Here's one table of attenuation for each type, gleaned from http://www.timesmicrowave.com/cgi-bin/calculate, Andrew's product guide (http://www.andrew.com), Belden (http://www.belden.com), and a couple of other sources. Remember, less is better (zero is ideal!) Cable Outer Loss in db/100' Type Diameter (at 2.5Ghz) ---------------------------------------------------------------------- LMR-200 0.195" 16.87 LMR-400 0.405" 6.76 LMR-600 0.509" 4.42 LMR-900 0.870" 2.98 LMR-1200 1.200" 2.26 Belden 9913 0.405" 8.15 Belden 9914 0.405" ??? LDF1-50 0.250" 6.14 LDF4-50A 0.500" 3.91 LDF4.5-50 0.625" 3.72 LDF5-50A 0.875" 2.27 LDF6-50 1.250" 1.68 LDF7-50A 1.625" 1.44 For Times Microwave's big cable comparison chart, go here: http://www.timesmicrowave.com/cgi-bin/byteserver/products/commercial/selectguide/LMRGuide.pdf To sum up: Use the best quality cable you can afford, at the shortest length possible. A couple of db here and there really add up. If you want to put an antenna on the roof, look into weatherproof enclosures for your router, and mount it as close to the antenna as possible. Then run your ethernet cable as long as you need (up to 100 meters!) ~~~~~ Q: What's a BNC/SMA/N/UHF connector? A: The US Navy apparently has some photos and descriptions up here: http://ewhdbks.mugu.navy.mil/coax_con.htm (We've done our own at http://nocat.net/connectors.html ). Here are some short descriptions. We have pictures of some; if you have any, send 'em in! =) BNC: Quick-connect half turn, same as on 10base2 ethernet. Fairly high loss at 2.4Ghz, but common and cheap. 'BNC' stands for 'Bayonet Neill-Concelmann'. Don't use these as they break down very quickly at microwave frequencies. TNC: Threaded version of BNC. Works well through 12Ghz. N: Threaded, larger connector common on many commercial 2.4Ghz antennas. Works great, kinda big (but great for thicker cable, like LMR-600.) 'N' was evidently Neill's connector. UHF: Usually, this is a coarse-thread version of the N. Not usable for 2.4Ghz, but frequently confused with the N. According to the ARRL Microwave manual, it's probably an SO-239 or PL-259, but frequently called 'UHF'. Avoid. C: A quick-connect version of the N. When possible, avoid bayonet type connectors, as their threaded counterparts tend to do better in microwave ranges. 'C' was evidently Concellman's connector. Fairly rare. SMA: Very popular, small, threaded connectors. Work great through 18Ghz. 'Sub-Miniature A'. Small and common, but no good for bigger cable (like LMR-400) without using an adapter. SMB: Quick-connect (push-on) version of the SMC. SMC: Very small version of the SMA. Good through 10Ghz, but only accepts VERY small (high-loss) cables. APC-7: 7mm plug, usable through 18Ghz. A sexless connector. High grade, expensive, fairly rare. 'Amphenol Precision Connector'. When in doubt, look at the ARRL UHF/Microwave Experimenter's manual, pp. 5-18 and 5-19 (ISBN# 0-87259-312-6). You must have this book if you're serious about learning about the mysteries of Microwave. Remember that each connector in the system introduces some loss. Avoid adapters and unnecessary connectors whenever possible. Also, commercially built cables tend to be of higher quality than cables you roll yourself (unless you're really good and have the right tools...) Whenever possible, try to buy a premade cable with the proper connectors already attached, at the shortest length you can stand. 802.11b gear doesn't put out much power at all, and every little bit helps extend your range and reliability. When matching cables, you may encounter connectors of reverse polarity (male + female swapped, with same threads), reverse threading (left-hand instead of right-hand thread), or even reverse polarity reverse threading (both). Make sure you know what you're getting before you order parts online! ~~~~~ Q: What's a pigtail? A: Most commercial 802.11b cards that still have external antenna connectors on them (an ever-diminishing number still do...) have proprietary connectors, impossible to identify through regular channels. If you can identify it, expect to be asked to pay hundreds (or even thousands) for a matching connector. The reasons for this state of affairs are left as an exercise for the reader. :( A pigtail is a small segment of cable that has a proprietary connector on one end, and a more common connector (frequently a male 'N') on the other. Card manufacturers will sell you these short pieces of cable for a mere $80+. Fortunately, some cable makers aren't as eager to gouge and will sell them in quantity for $10-$40, depending on the type and how many. Short of soldering a cable directly to your radio card, they're the only way to connect an external antenna (and extend your range.) Things to keep in mind about pigtails: * They are radio manufacturer (and even model #) specific. Make sure you get the right pigtail for the radio card you're using. * Get the SHORTEST PIECE OF WIRE YOU CAN FIND. I've never seen a pigtail made from microwave rated coax; the longer the pigtail is, the more your signal gets chewed up before it even hits the antenna. * You can frequently get a better price by purchasing 10 or more at a time. Ask for group discounts. Go in on them with your buddies (or post to any of the community groups to find people; group buys are increasingly common.) * The PCMCIA cards typically have tiny connectors, and so the pigtails have tiny plugs. They are VERY fragile. Don't yank 'em or they will break. It's easy to do. I know, I've done it. It's no fun. Q: Why did you use a PCI-to-PCMCIA adapter? Is it not possible to use a straight PCI or ISA wireless card? A: In short, the PCI and ISA wireless cards are not as common as the PCMCIA cards, and support for them is still sketchy, whereas there's quite a few known working and supported PCMCIA 802.11b cards in Linux. Feel free to try a normal PCI/ISA card -- if you can get it working, please let us know how. We'd definitely be interested to hear about it, as it might save a bit of cash for people attempting the same. 2003-03-21 Pete Siddall sent this in: The Netgear MA311 PCI card runs nicely under Linux with the orinoco-pci 0.13b driver. Do get the newest version of the driver from ozlabs though, I tried 0.11 and could crash it easily under load. The card takes an external antenna and seems to have a good radio - better than my PCMCIA orinoco. No, I don't work for Netgear... I usually like D-link stuff but their current PCI card, DWL520+ uses an acx100 chipset and AFAIK has no Linux driver at this stage. Don't know about DWL-520 which is a completely different card. ~~~~~ Antenna Questions ~~~~~~~~~~~~~~~~~ Q: What kind of antenna do you use? A: It depends on the application. Antennas have two important practical characteristics: directionality and gain. Directionality means that it sends and receives better in one direction than in another. Gain tells you how much better it goes in that direction. Typically, the higher the gain, the better the range (in the direction that the antenna radiates in.) Antennas do NOT give you more signal than you started with (that's what amplifiers are for.) What they do is focus the signal in a particular direction, like turning the head of a flashlight. It doesn't make the bulb any brighter, it just focuses what you have into a tighter area. It gives you a brighter beam at the center, at the expense of having to cover a smaller area. There are about four general classifications of antennas out there (listed in rough order of increasing directionality): Omni ~~~~ These radiate outward in all horizontal directions roughly equally. Imagine putting an enormous donut around the center pole of an omni. That is what the radiation pattern looks like. These are good for covering a large area where you don't know which direction your clients might come from. The downside is that they also receive noise from every direction, and so typically aren't as efficient as more directional antennas. They look like tall, thin poles (anywhere from one to five feet long) and tend to be expensive. The longer they are, the more elements they have (and usually the more gain, and the higher the price) They are mounted vertically, like a popsicle stick. Sector (patch antenna) ~~~~~~~~~~~~~~~~~~~~~~ Picture an omni with a mirror behind it. Sectors radiate in one direction, with a beam as wide as 180 degrees, or as narrow as 60 degrees (or less). They excel in point-to-multipoint applications, where several clients will be accessing the wireless from the same direction. Sector antennas come in a variety of packages, from flattened omnis (tall, thin, and rectangular) to small flat squares or circles. Some are only 8 inches across, and mount flat against a vertical wall or on a swivel mount. They can also be ceiling mounted to provide access to a single room, like a meeting room, classroom, or tradeshow floor. Like with omnis, cost is usually proportional to gain. Yagi ~~~~ A yagi looks like an old television aerial. It is either a flat piece of metal with a bunch of horizontal cross pieces, or a long pipe with bunch of washers along its length. The typical beam width can vary from 15 degrees to as much as 60, depending on the type of antenna. As with omnis, more elements usually means more gain, a longer antenna, and higher cost. Some yagis are simply bare, like a flat christmas tree pointed vaguely in the direction of communications. Others are mounted in long horizontal PVC cans. They can work well in point to point or point to multipoint applications, and usually can achieve higher gain than sectors. Dish ~~~~ In some ways, a dish is the opposite of an omni. Rather than try to cover the entire area, a dish focuses on a very tight space. Dishes typically have the highest gain and most directionality of any antenna. They are ideal for a point to point link, and nearly useless for anything else. Dishes can be solid or mesh, as small as 18" across or as big as you like (a 30 foot dish is possible, but probably not very convenient.) A dish that can send an 802.11b signal more than 20 miles can be as small as a few feet across. In terms of gain for the buck, dishes are probably the cheapest type of antenna. ~~~~~ Q: Do I have to use an antenna from the same manufacturer that made my card? A: NO. As long as the antenna is rated for the channel you want to use (and you can get matching connectors for it) it will work fine. Note that not all radio cards come with external antenna connectors. Make sure yours does before trying to use it with an external antenna. ~~~~~ Q: Do I need the same kind of antenna on both sides of a link? A: NO. In fact, you might not even need an antenna on both ends (your card does have a tiny internal antenna, which might be enough depending on what you're doing.) As long you are using antennas tuned to the frequency that your radios are using (about 2400Mhz), it doesn't matter if they're yagis, dishes, or made of aluminum foil. ~~~~~ Q: What are the frequencies that 802.11b uses? A: In the USA, 802.11b uses any of eleven channels: Channel 01 : 2.412 GHz Channel 02 : 2.417 GHz Channel 03 : 2.422 GHz Channel 04 : 2.427 GHz Channel 05 : 2.432 GHz Channel 06 : 2.437 GHz Channel 07 : 2.442 GHz Channel 08 : 2.447 GHz Channel 09 : 2.452 GHz Channel 10 : 2.457 GHz Channel 11 : 2.462 GHz (the above was pasted from Jean Tourrilhes' iwlist program, see the software section below.) Keep in mind that adjacent channels overlap quite a bit. To be absoultely clear of interference, adjacent APs should come no closer than five channels apart. So if two have overlapping coverage, come no closer than: 1 + 6 or 2 + 7 or 3 + 8 or 4 + 9 or 5 + 10 or 6 + 11 or 7 + 12 (3/30/2003 note: I believe this should read 'four channels apart' rather than five.) This provides three channels that can be used at the same time: 1, 5 and 11. A little bit of overlap doesn't hurt too much (until both networks get really loaded down.) Alot of overlap can hurt your throughput. Separate busy networks using the same channel can kill it. But there has been new research done that shows it possible to use 4 slightly overlapping channels with (almost) no interference. Under this scenario you can use channels 1 - 4 - 7 - 11. In some countries (like France and Japan), you may have fewer (or more!) channels available. Your manufacturer should tell you so, but remember that wherever you are, you as the operator are responsible for making sure that you aren't interfering with something more important than your net access. =) ~~~~~ Q: Where can I get an antenna? A: Try any of these (at your own risk!): http://www.superpass.com http://www.netnimble.com/products/index.html http://www.teamelectro-comm.com/shopping/ (search for "2.4 Ghz antenna") http://www.maxrad.com/_2ghz-6ghz.sht http://www.hyperlinktech.com/ http://www.teletronics.com/Products/products.htm Remember, any antenna rated for 2400Mhz (2.4Ghz) should work fine. ~~~~~ Q: What about amps? A: They're expensive, typically noisy, and frequently not a good idea. However, we're looking into it. Check back later. =) ~~~~~ Specific Applications ~~~~~~~~~~~~~~~~~~~~~ Q: Can I hookup my classroom / office / house? A: Yes, you can. ~~~~~ Q: Can I use 802.11b to unplug my Desktop machines, so I don't need yards of CAT5 running around the house? A: Of course. You'll want a PCMCIA to PCI (or ISA) bridge. Then just use a regular PCMCIA radio to talk to the rest of the network. This is also how to setup a desktop machine to be a wireless gateway without spending money on an AP. Take a look at: http://www.oreillynet.com/pub/a/wireless/2001/03/06/recipe.html ...if you want to do that. Or, use the WRP gateway-on-a-floppy at http://nocat.net (I'll leave this in for now, but the WRP project is dead as Marley. If you want a Bridge then go buy a Linksys WET-11 and be done with it!) ~~~~~ Q: Can I setup a point to point link to get internet access to somewhere that can't otherwise get it? A: Yep. Use high gain, directional antennas. More on that later. ~~~~~ Q: Is it legal? A: I AM NOT A LAWYER. As the radio operator, it is up to you to determine what is legal for wherever you happen to be! That said, at least in the USA, it is most definitely legal. It only gets hairy with very high gain antennas on point-to-multipoint links, or when using amplifiers. Check out these great resources: Tim Pozar's FCC Part 15 discussion: http://www.lns.com/papers/FCCPart15_and_the_ISM_2.4G_Band.index The full FCC Part 15.247 text at the GPO: http://www.access.gpo.gov/nara/cfr/waisidx_00/47cfr15_00.html (just click on 15.247, "Operation within the bands 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz.") Remember that unlicensed emissions have the lowest legal leg to stand on. Don't interfere, use the lowest power (and most directionality) that you can, and play nice. ~~~~~ Community network questions ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Q: Why would I bother setting up community access to a service I'm paying good money for? A: Good question. Maybe you're just a nice guy. =) Maybe you're willing to share a service you're paying for (but probably not utilizing fully) with your local community. The NoCat idea is to provide further incentive by giving anyone who sets up a public access node privileged access to all of the other nodes. Take a look at the NoCat RFC at http://nocat.net/nocatrfc.txt to see how we plan to provide for that. The software is currently a work in progress, but would require a Unix (probably Linux or BSD) machine to act as the gateway traffic cop, and communicate with a central, load-balanced authentication system. Ultimately, I'd like to be able to open my laptop wherever I happen to be in town, and get a free, fast connection to the Internet. And I'd like anybody else who's willing to participate to do the same. Thousands of people around the world are trying to make the same dream a reality. ~~~~~ Q: How can I share my DSL/ISDN/T1/Cable Modem with my neighbors? (The Simple Way). A: First check the Terms of Service (TOS) of your agreement with your ISP. Some ISP's prohibit connection sharing, while others welcome it (it is a complicated world out there!). AFAIK all cable companies prohibit connection sharing, while many DSL providers welcome it. Buy an Access Point with an external Antenna. If needed, replace the antenna with a small sector or panel antenna. Put the Access Point between your DSL modem and your firewall. Configure the AP as as needed according to the manufacturer's instructions. Q: My neighbor is sharing her connection, how can I connect to it? A: The simplest way is to put a WiFi card in your laptop and see if you can connect. If you are very close, and your neighbor's signal is strong, this will be all that you need. If you have an existing ethernet network in your house, you could use a wireless to ethernet Bridge, like the Linksys WET-11. One NoCat member has a 16 dbi sector antenna in his attic attached to a Linksys WAP-11. His neighbor across the street gets 11 mbps connectivity throughout her house on a Mac iBook with built in Airport wireless card. Another neighbor one block down and one block over has a 24 dbi grid antenna connected to a Linksys WET-11. He needs the 24 dbi grid antenna to get the same signal because of trees. Trees Suck up microwave emissions. Q: How can I provide community access over my local internet connection? (the harder, but more flexible way) A: (original FAQ answer) Many people are working on that problem right now. Join the mailing lists, write software, help shape the course of the "last mile" Internet and make it happen! Currently in NoCat we have a number of 'repeater' nodes that receive wireless signal from another node, and then redistribute that signal to the local household via wired ethernet and to the world at large via a second wireless card. Most of these are using Soekris or Via boxes. The Soekris is a low power option (less then 5 watts of power), while the VIA is just a small PC. An example VIA configuration has a VIA mother board booting the Pebble Linux distribution off of a compact flash card. It also has two wireless cards in a PCMCIA to PCI adapter card. One of the wireless cards operates in 'client mode,' in which it acts like a regular client. This provides the Via with network connectivity. The second wireless card is set up with the HostAP drivers. This makes the VIA into a wireless Access point. A little routing magic is set up, and all is good with the world. References ~~~~~~~~~~ Some big wireless community pages: http://seattlewireless.net http://www.bawug.org http://www.personaltelco.net http://www.toaster.net/wireless/community.html http://www.nocat.net http://www.wscicc.org/ - A Bandwidth Cooperative, with sample bylaws and organizational information Great Wireless link design CGIs: http://www.gbonline.com/~multiplx/wireless/page09.html Pebble - a smallish linux distribution that can run read only off of a compact flash card: http://www.nycwireless.net/pebble/ US Navy microwave connector reference (with pictures): http://ewhdbks.mugu.navy.mil/coax_con.htm Some equipment links: http://www.superpass.com/ http://www.netnimble.com/products/index.html http://www.teamelectro-comm.com/shopping/ (search for "2.4 Ghz antenna") http://www.maxrad.com/_2ghz-6ghz.sht http://www.hyperlinktech.com/ http://www.teletronics.com/Products/products.htm Part 15 discussion and documentation: http://www.lns.com/papers/FCCPart15_and_the_ISM_2.4G_Band.index http://www.access.gpo.gov/nara/cfr/waisidx_00/47cfr15_00.html Mailing lists ~~~~~~~~~~~~~ NoCat: nocat-subscribe@pez.oreillynet.com SeattleWirelessDev: dev-subscribe@seattlewireless.net PersonalTelco: http://lists.personaltelco.net/mailman/listinfo/ptp BAWUG: http://lists.bawug.org/mailman/listinfo/wireless/ Glossary ~~~~~~~~ Line of Sight: If you can see another point, with no physical obstructions in the way, you have line of sight to that point. 2.4Ghz communications work best with no obstructions in the path, but are still possible through many materials (at significantly reduced range.)