Public Wi-Fi: Share, but Wisely

By Carla Schroder

March 20, 2007

Rather than hoarding all your wireless bandwidth, you might want to share it, or at least provide an enticing sandbox for passers by.

Ever since wireless computer networking was invented a lot of folks have invested a lot of energy into developing easy ways of sharing Internet connectivity. Let's get the bad method out of the way first, which is purposely setting up an unsecured access point for your network. That is just plain daft, because you're exposing yourself to all kinds of abuses and mischiefs. You know this, I know this. So read on for better ways of sharing wireless Internet.

Safe Sharing
It is nice to share, but be smart about it. Set up a separate bandwidth-throttled subnet just for random roaming users, or to be generous to your neighbors. This is a nice thing because it provides an alternate connection during outages, or connectivity for visiting friends and relatives of neighbors who don't have Internet at all. (I know, it's difficult to imagine, but there are such people in the world, and I understand that a sizable percentage of them do not feel deprived. Shocking, but true.) Some folks are just plain short of money. It's easy to get a good used computer for cheap, but not everyone can afford that monthly bite for regular Internet service.

The safest way I know to do this is to use a separate wireless access point just for sharing. Put it on a completely separate subnet. Throttle the bandwidth to prevent hogs from sucking up your whole connection, and if you really want to be nice throw in a DHCP server. Firewall off all traffic between your LAN and the freeloader connection. With cheap wireless/broadband routers like the Buffalo WHR-G54S, which you can find for under $40, it's both dirt-cheap insurance and generosity. To stretch your money even further, replace the stock firmware with DD-WRT to turn your $40 router into a $500 router.

You might wish to proclaim your generosity with a NoCatSplash page, which comes with DD-WRT. All this does is greet visitors to your generously-provided Internet portal with a friendly greeting, so they know who to direct their feelings of gratitude towards.

Wireless Meshes
This sort of random, grassroots sharing is a good thing, so as usual some brainiacs thought it over and figured out a way to make it even better. And thus was invented OLSR, or the Optimized Link State Routing protocol. This is a slick protocol that seeks out other wireless nodes and automatically sets up routing tables to create ad-hoc mobile networks. It's a busy little protocol that works hard and eats up CPU cycles. Fortunately, there is a lightweight implementation called Freifunk Firmware. This is designed for embedded routers like the Buffalo WHR-G54S, the Links WRT54G series, and similar devices. Most Linux distributions designed for the WRT54G-type wireless routers include some form of OLSR, but Freifunk is the preferred firmware for ease of use and features.

Wireless mesh networks are especially useful in towns that have community wireless projects. Municipal wireless projects sound good on paper: cover the notorious "last mile" with wireless repeaters instead of laying cable. But this still falls short, because Wi-Fi (which is all implementations of the IEEE 802.11 specification) runs into a number of obstacles. It is line-of-sight, so even if you have repeaters on every block there are still going to be structures and hills that block signals. There will be interference and reflections. So there is still room for grassroots efforts to share the bandwidth.

There's an even easier way that doesn't cost very much: Meraki repeaters. These are ingenious little 802.11b/g repeaters that are literally plug-and-play. The fine folks at Meraki suggest that at least one in ten Meraki repeaters be connected to the Internet for good performance, and the rest function as simple repeaters. There are indoor models that currently sell for $49, and outdoor models for $99. You don't have to be a noble altruist — Meraki supplies a Web-based Dashboard for monitoring your network, and it also includes billing software. Dashboard is hosted by Meraki on its servers. It's free for free networks; if you're charging for your services, Meraki takes a percentage.

Being a Fabulous WISP
Odessa Office Equipment is my favorite WISP (Wireless ISP) success story, because its founder and owner, Marlon Schafer beat Paul Allen at turning a profit selling wireless Internet. You may recall the heady days of the new millennium, when Mr. Allen was pouring hundreds of millions of dollars into Metricom's Ricochet network, which wound up declaring Chapter 11 bankruptcy, and was eventually sold for just over eight million dollars. Gosh knows you can't blame a billionaire for trying, and if I had that much money to play with I hope I would also have grand ambitions, and not just spend my days filling my swimming pool with hundred-dollar bills to wallow in.

But while the big boys were flinging big wads of money all over the place, Mr. Schafer took out a $10,000 loan, stuck an antenna on top of his grain silo, signed up ten paying customers, and has been profitable ever since. Back then Mr. Schafer was a pioneer; these days it's easier than ever to do the same thing. Broadband Internet is inexpensive and pervasive. Maybe you've been thinking "I'm getting all this bandwidth that I'll never use- I could share it and get back a little money."

Or maybe you're in a similar situation to mine. I live way out in the sticks, right at the edge of DSL availability. I get good reliable DSL, but across the road my poor neighbors only get dialup. It's nice and flat here for good line-of-sight, and I have toyed with the idea of sticking an antenna on my roof and becoming the neighborhood WISP mogul. I could sell monthly service, or hourly for travelers and visitors.

What kind of gear would this require? This would be a perfect excuse to purchase some nice high-powered Ubiquiti wireless gear. Ubiquiti makes high-powered wireless interfaces based on Atheros radios, so they are fully-compatible with Linux thanks to the MadWiFi driver project. You can purchase the wireless adapters separately and build your own stout boxes from scratch, or get a nice prefab hotspot or access point. These come with firmware, and they are friendly to installing your own firmware.

Gotchas
Being a wireless mogul has its pitfalls. We're using unregulated frequency spectrums- 900mhz, 2.4 ghz and 5 ghz- so there is nothing to prevent competition and interference from other devices that want to use the same spectrums. Microwave ovens and cordless telephones are two notorious examples of devices that interfere with wireless computer networking. As more people use Wi-Fi, we'll see more contention between networks. And security is always a pain.

But those are mere technical problems, and are therefore solvable. Small-scale community wireless networks are wonderful things that fill important niches, and are great projects for ace Linux geeks.

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