Can Faraday Cages Tame Wi-Fi? 145
mrraven writes "An article at TechWorld discusses the increased need for wireless network security. One possible solution to this problem is the use of building-wide Faraday cages to block the wireless signal from 'leaking'." From the article: "Small installations of RF shielding don't have to be expensive, and the basic concept of a Faraday cage can be extended to all kinds of small everyday objects. Leather wallets sandwiched with a conductive RF-shielding layer can prevent RFID scanners from reading personal information implanted in everything from RFID-enabled access control cards to some credit cards; they're widely available for as little as US$15. For those favoring a more DIY route, several Web sites have information on how to make an RFID-blocking wallet with duct tape and aluminum foil."
The truth may be out there... (Score:5, Funny)
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I think the idea is to keep the voices from leaking out.
Re:The truth may be out there... (Score:5, Informative)
No, but it will keep the voices from using your neighbor's access point.
Re:The truth may be out there... (Score:4, Funny)
BTW, I can just image the "scare-the-consumer" infomercials for those. "Anyone just walking by can steal your entire life! Stop them now with our high-tech disposable Super-TF-Wallet! Just 3 easy payments of $19.95 and you...."
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Why would you want a chain mail(*) wallet? It doesn't have to flex that way, and the mail won't give you some kind of special resistance to RF. With the right setup of chicken wire, you could probably do the same thing, for about $20.
(*: Like "breastplate", "chain mail" is a perfectly valid English word.
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So this is essentially a giant tinfoil hat for your office? Will it stop the voices as well?
I don't think it will stop 'the voices' - they are probably your managers
Re:The truth may be out there... (Score:5, Interesting)
Our office has IR tempered glass (which is quite common in "all-glass" buildings nowdays.
Stops WiFi dead in its tracks. The signal drops by 20+db when going outside the building to the point where you can no longer home in with a normal receiver. Granted, this will not help against a professional attacker, but it is more then enough against random wardriving k1dd10tz.
So if you have to chose between two buildings which are all-glass and glass windows + wall for a new office the all-glass is better as far as WiFi is concerned. Wardrivers aside, allocating channels without worrying about neighbours is quite a nice thing to have.
20 db drop is not always enough. (Score:2, Interesting)
Go past legal and at lot more than 30db can be done.
20 db drop is only good if you network stays under 20db itself. If you fit a 30db arial inside a 20 db shield you shoot self in foot. A farday setup cannot be broken by just fitting a larger arial. But it can block mobile phones. Both ways have a price.
Not just WiFi (Score:3, Interesting)
Can you hear me now? (Score:4, Informative)
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For a quick proof of concept, your microwave oven's FC will 'stop' your cordless phone, but will not stop your cell phone (try it!).
Even 2" aluminum schielding will not stop some frequencies, e.g. short gamma-rays!
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Probably
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Yes.. it will stop all the voices coming to the cell phones of people inside the building.
Seriously, what kind of crazy idea is this?
What about windows? (Score:5, Insightful)
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Re:What about windows? (Score:5, Funny)
Oh wait...
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If you can't secure a wireless network to the point where there are much bigger security issues than someone attempting to wardrive it, you shouldn't be defining a company's construction plans.
Re:What about windows? (Score:5, Informative)
Brett
Re:What about windows? (Score:4, Interesting)
Not necessarily. I would imagine that some kind of transparent conductive coating could be sprayed onto the glass, and reapplied periodically. For example, my car's windshield has a conductive layer that is used as the radio antenna (it also inconveniently blocks my tollway transponder, something I did not foresee when I ordered the thing.) I'm sure that there would be plenty of window manufacturers that would be happy to sandwich a clear conductive layer in their products were there a demand for this.
Yeah, you're right it's not that hard to provide a decently secure wireless setup
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Heck, there's probably already such a product out there, I'm just too lazy to actually
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Insect nets (Score:2)
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Window problem already solved (Score:2)
We have this in New England. (Score:2)
Seriously, blocking can't be to bad if you plan ahead. They already make several flavors of wallboard with various other additions for specialty applications - wire mesh should be worth it - and they do have styro' insulation with metal foil backing.
I've lived in a older house with plaster walls with wire mesh backing (it was common in the 50s or so) plus window screens did a fairly good job of cutting down wifi.
At work the rebar concrete and steel framing in some of our build
Re:What about windows? (Score:4, Insightful)
Re:What about windows? (Score:5, Insightful)
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If, for example, a perforated aluminum film is applied, it can be
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[..]
>,and I doubt would ever become practical.
I regularly visit a customer which owns a building constructed as
a faraday cage. It has large windows (3 meters tall) which looks
normal to me, but the whole building seems
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UK defense system (Score:5, Interesting)
Re:UK defense system (Score:4, Interesting)
Faraday Cages will work (Score:5, Informative)
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There is stopping you from having windows. All you need is a metal screen either on the inside or outside. This also allows you to open the windows for some air. There is also EM blocking glass that has a very thin mesh overlaid or embedded which is basically invisible (similar to some touch screens).
The only times I have been in EM protected areas with no windows is when there was confidential work being done and they didn't
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Re:Faraday Cages will work (Score:5, Informative)
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It's all about the wavelengths. If you want to block ALL EM, then yeah, you need a solid metal enclosure. But, just like you can see into your microwave oven through a wire mesh, you could also put windows on your faraday cage as long as they were covered by an appropriate wire mesh.
IIRC, the 2.5GHz of a microwave oven beam and the 2.4GHz of WiFi are both around 12 cm wavelength. The holes in the mesh on your microwave are so small that the microwaves can't make it through it without severe attenuat
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You are assuming that a wall/roof/floot that incorporates a thin layer of something conductive (say aluminium-foil) needs to look like a "metal wall", this is in no way true. Where I live building-regulations already require a plastic vapor-block in all outside walls, these are *inside* the walls (on the "warm" side of the insulation) and not even visible. I fail to see how it'd make the building less nice to be in if
Leaky (Score:5, Interesting)
Once again, it's probably better to focus on good encryption, though this is hardly much help to defeat certain on-site DOS attacks. Then again, that's what your security force is for
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That's actually a very good idea (I can honestly say I had not thought of that), however you'd also have to faraday cage all of the windows, floors, and cielings as well. Outside the building, (if you own the property) a bunch of other wireless access points sending random info etc might provide some good "jamming", or perhaps even as a honeynet.
MRI (Score:1)
Granted, windows aren't a problem in the magnet room, but the doors are. So it becomes interesting to try and develop a door that can seal out the frequencies of interest effectively. It's tough, but some magnet rooms can effectively seal off noise while allowing humans to enter and leave.
Re:Leaky (Score:4, Insightful)
The two types I've seen in photo darkrooms are:
1) The light baffle. The entry doorway is just an 'S-shaped' hallway that requires you to turn a couple of times to pass through. There doesn't need to be any door to open/close, but as long as it isn't lined with a material reflective to what you are trying to keep out, you're ok. Look under your sink at the drain catch for the idea. The nice thing about this style door (for darkrooms, etc) is that you never need to worry about having to mess with any door mechanism in the dark. It's completely open to wander in and out (for people, air circulation, etc.)
2) The revolving door. There is never an open conduit from the outside to the inside at any time. The opening closes off from the external environment completely before reaching the point where it opens to the internal environment.
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It migth still help reduce interference from the enormous number of wireless devices existing in some downtown neighbourhoods.
Cell Phones (Score:5, Insightful)
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Oh, come on (Score:5, Insightful)
The best wireless security solution is just to not use wireless. Yes, it's sexy. Yes, I know it can be a pain when there's a split in an ethernet cable that's in the rafters. Yes, I like to be able to use this laptop on the couch because it helps my creative energies get flowing. But seriously, if I were at all concerned about security, I'd just stick at CAT5E into the side and be done with it. Big wireless deployments are things for college students and people who like cafes. If I were running a business, I wouldn't throw money at a wireless project to begin with, let alone build an elaborate jamming/shielding system to correct problems which could've been avoided by not doing anything in the first place.
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For example, WiFi has saved the hospital I work at tens of thousands (at least). C
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You know, we have this stuff called "cryptography"... it has been used to secure communications for quite a while now sucessfully to secure some pretty important things. In fact, I bet you use it directly or indirectly on a daily basis. I have some interesting news: you can use this magical crypto stuff to secure your own wireless communications too! No, seriously! Believe it or not, people actually can and do run secure wireless networks out t
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Oh, really? Tell me, about how much AES-256 ciphertext would you need to decrypt it all without the key?
Thank god we got rid of wires (Score:5, Funny)
Sheet rock (Score:2, Interesting)
Still probably going to be rather expensive, it being a whole "chicken and egg" type of situation.
It's probably cheaper on the whole to use good wireless security and regularly test for employees opening unsecured wirel
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Expensive yes, but available. Lead lined sheetrock is available for doctors offices and other places that use X-rays.
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http://www.leadshield.com/sheetrock.htm [leadshield.com]
http://www.maycoindustries.com/sheetrock.htm [maycoindustries.com]
http://www.soundproofing101.com/soundproofing_7.ht m [soundproofing101.com]
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Utterly, completely, and laughably incorrect.
In order to form a Faraday cage - all the edges of the all the mesh in all of the sheetrock have to be connected together (very expensive in terms of labor) without
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Faraday Cage (Score:3, Funny)
Have you ever actually used a Faraday cage? (Score:5, Informative)
Real Faraday cages are an unmitigated pain to deal with. The ones used for RF testing typically have a heavy door, like a walk-in refrigerator, with conductive fingers all around the doorframe that seal against the door. It's not enough to have metal; all the metal has to be connected. And slots will pass a wavelength up to the length of the slot.
The ones used for high-security classified work are even worse. They're made of welded metal panels. They're a few feet off the ground, so the underside can be checked. Any I/O is fibre optic. Power goes in through huge low-pass filters. Air goes through metal mesh filters. Double doors work like an airlock, and there's a compressed-air system to force the RF-tight door seals. Periodic testing (transmitter inside, receiver outside) insures the tank is really RF-tight.
Not a fun work environment.
Painting the walls with conductive paint is a joke.
There's nothing mysterious about any of this. RF propagation is well understood, and the test gear is easy to obtain. Ask any ham.
We have a Faraday caged room (Score:2, Interesting)
The system works quite well, but we still get quite a bit of leakage through the two doorways (they have a copper lining as well). We can still pickup cell phone calls within 3-4 feet of the doorway (when closed), but
Wallet (Score:2)
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Google is your friend. [google.com]
Looks like this [difrwear.com] is where you want to go.
shielded windows and wallets (Score:3, Interesting)
This seems like its overkill - be more sensible to have some encryption and maybe a system where you have to login to get access to the web is more practical. This way you get to keep what few bars you have on the cell.
With respect to the RFID in passports or on cards, yeah you might want a Faraday cage in your wallet but I wonder how long it is before that becomes classified as suspicious behaviour. I can just see those TSA officials getting red in the face that you'd dare question their authority by using a shielded wallet and having you detained for an hour - just enough to miss your flight.
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I doubt it... basic physics (Score:2)
Not very practical for a building or even a room, except for a special EMI testing room.
Or maybe I'm completely missing something. Maybe it doesn't take that m
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Go optical.. (Score:2)
Why does it have to be a physical? (Score:5, Interesting)
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Ummm..... (Score:1)
I must already have this! (Score:4, Funny)
And WiFi? No way! I have 3 access points (One in attic, one in basement, one on the same floor as the PC using it (10' away on the other side of a wall) and do you think I can get a reliable signal? Hell no, but if I am in my car I can pick it up 2 blocks away.
My wifes old 900MHz phone works fine, my new 5.8GHz phone? it'll only work if I stay in the same room as the base-station and the people can only hear me when I yell.
If I try using 802.11a, I get good results (despite my wifes phone and 2 microwave ovens in the house), my CRAP (Completly Ridiculous Assinine Pet) theory is that the lower frequency passes through the super-human drywall that my house is made of. But to compete with that theory I can't understand why a Nerf-ball is able to dent the wall.
Time to move I guess.
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Get Smart (Score:1)
HOWTO: protect your wireless network (Score:1, Informative)
(b) declare an ipsec tunnel from your laptop to your gateway.
(c) set ipsec policy to require it for all traffic.
(d) rtfm
ip link set dev wireless arp off up
ip address add dev wireless local 192.168.1.2 peer 192.168.1.3
ip neighbor add dev wireless to 192.168.1.3 lladdr 00:11:24:2c:38:c6 nud permanent
setkey -c >/dev/null <<-END
Until the remodelers get through with it (Score:1)
No doubt, there are some sensitive defense department or NSA facilities that already have RF blocking capability. But maintaining it probably requires careful attention to anything that might compromise it, including periodic testing. In other words, high expense.
The sort of people t
Wires? (Score:2)
Inadvertent Faraday Cages (Score:4, Interesting)
So yes, it does work.
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Can you hear me now? No? Good.
Needs to be GROUNDED (Score:2)
why is everybody so concerned about wireless secur (Score:2, Interesting)
Since the Paranoia-meter is Rising... (Score:2)
OMG (Score:3, Funny)
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Pencils, the graphite in the pencil lead sucks up microwave something fearce. Try it, put one of those golf pencils (without the metal ferrel for the eraser) on top of your coffee cup before you nuc' it in the microwave, and compare the temp to a normaly cup! If the cops weren't using lasers, my car would be painted