It's worse than that. Most wireless mesh technologies allow anyone to advertise themselves as the quickest route to somewhere, provided they're closer to the source than the real destination. They could then either a)modify the packets (if the nodes aren't using end-to-end encryption) or b)drop them.
This is a good question and, last I checked, an open research topic. One workaround is to only accept route advertisements from a trusted set of routers.
Water is actually not opaque to 2.4ghz radiation. If it was, your food would burn on the outside while staying cold on the inside. It's more like it's translucent - some of it gets through, some doesn't. Your plate may be more opaque to microwave, not because it contains water, but because it happens to be made out of something else that happens to absorb microwave radiation as well.
Water interferes much more significantly with microwave radio transmissions at above 10 ghz.
Why not? WDS can be used to build mesh networks, just not very good ones. WDS meshes typically use the ethernet spanning tree protocol (STP) for their routing algorithm, which produces highly suboptimal routes most of the time. I have built a WDS mesh under linux with the HostAP driver and brctl. It worked alright with a couple nodes, but I wouldn't expect it to perform well if I tried to connect dozens of nodes.
Very good game. I like the daimyo system because
1) the game progresses even with 4 or 5 evenly matched players and
2) there's much less of the tedius unit-moving that occurs in axis and allies.
Other cool features: turn order varies from round to round, some tasks are done synchronously is Shogun which were done one-at-a-time in A&A (like buying units), and armies contain hand-to-hand units (samurai, spearmen) and ballistics (riflemen, bowmen). The ballistics get to roll first, and any hand-to-hand units killed can't fight back.
I've always thought it might be fun to play shogun on a risk board, but I've never tried it.
The manufacturer shall ensure that any software used in connection with the the voting system is not transferred over the Internet.
page 8-9
No voting system shall at any time contain or use any undisclosed software. Any voting system containing or using software shall disclose all source code, object code, and executable code of that system to the commission, and the commission shall make that source code, object code, and executable code available to any citizen upon reqest.
So, source code is available to any citizen, but it can't be distributed over the Internet? Why not?
Also, the manufacturer is required to do a background check on all contributers, so that rules out an open source development model.
Mandatory recount of paper ballots is required at 2% of precincts (chosen randomly). This is an improvement, but in my opinion, too low. 98% too low. The electronic count should be used to satisfy those who don't want to wait two weeks to find out who won, but electronic counts should never be considered trustworthy by themselves.
I'm guessing that's not what the author of the article understood, either. (If you didn't read it, you really didn't miss much.) He uses as an example passphrase:
"If we weren't all crazy we would go insane"
Which is a line from a Jimmy Buffet song. Not much entropy there to deter a pop-culture aware passphrase guesser.
My understanding of kerberos (please correct me if I'm wrong) is that it's a symmetric key system. Every computer shares a secret key with a central server that handles authentication.
The problem is that the central server, if compromised (or administered by someone of malicious intent), can authenticate anyone as anyone else to anyone else on the network. In other words, you have to trust a third party.
In a public key system, the worst thing the key authority can do is refuse to publish and/or sign your public key. You don't have to trust anyone but yourself.
Do RSA tokens work with linux and/or ssh? It seems like one would only need a modified ssh-agent for remote login and pam module for local authentication. I'd like to be able to walk up to one of my various linux boxes, insert a usb token, and have the machine log me in automatically, and to be able to ssh to other machines without being prompted for my password, and using the token's keypair.
That's interesting. So it's like what ssh does, but if I type a password for some other account by accident, the remote host doesn't capture the password?
I would like to get away from using passwords at all. The average computer user is compelled to remember so many passwords for so many separate accounts, that one usually resorts to writing them all down, or storing them in a text file, or setting them all the same, or using simple dictionary words that are easy to remember (and guess). I would rather use an authentication mechanism that is both secure and easy to use. Any mechanism that uses passwords is neither.
Passwords are insecure, since they may be captured by a keylogger. (I don't think I'm being paranoid to assume the probability of someone covertly installing keylogger software on one of the computers I type an important password on sometime in the next ten years is at least 50%, maybe close to 100%.)
Passwords are inconvienient because one must remember a unique one for each account. I would rather have a small hardware device I could stick in the usb slot to authenticate myself, and never have to remember another password for as long as I live.
It looks like they're just using the usb device as storage for one's keypair. Proper USB tokens, if I understand correctly, do all the encryption on the device and never divulge the private key. As such, they may be used with untrusted computers.
Fair enough, but for my purposes, the danger of someone stealing my usb token is relatively insignificant compared to the danger someone might get root on one of the computers I use and keylog my passwords as I log into accounts on that or another computers. Also, if my token is stolen I will know it. If my passwors are sniffed I won't.
This brings up another question I have: do usb tokens usually come from the factory set to a particular keypair, and can one reset them to a keypair of one's own choosing, or duplicate keys so one has a backup (possibly used to invalidate one's accounts or set a new public key) if one token is stolen or lost?
Passphrases are just long passwords with (usually) low entropy. They still have the same problems... You have to have a separate passphrase for each account, and you have to trust the computer you're using not to log your keystrokes. I would much rather carry around a device that can authenticate me and never have to remember a password again.
Why don't we all just switch to USB tokens for authentication? You have one device that can authenticate you by generating an RSA signature without divulging any information that would allow someone else to pretend to be you. It amazes me that more people don't use these things. I've never used one, but have considered ordering one. Does anyone out there have experience with USB tokens? Is there a good model/brand to buy? Is it easy to get them to work with Linux and ssh? Do any brick-and-mortar stores sell them?
I'm not sure why Google would need to host Wikipedia for that.
Often, the most authoritative publicly available article on a given subject is in wikipedia, and often these articles have a high page rank.
If someone clicks on a google search result link, and the site is slow (as is sometimes the case with wikipedia), that reflects poorly on google. If google can make a large number of the pages it links to more responsive, it improves user experience, and makes google look good.
(b) The maximum peak output power of the intentional radiator shall not exceed the following:
...
(3) For systems using digital modulation in the 902-928 MHz, 2400- 2483.5 MHz, and 5725-5850 MHz bands: 1 Watt. (4) Except as shown in paragraphs (b)(3) (i), (ii) and (iii) of this section, if transmitting antennas of directional gain greater than 6 dBi are used thepeak output power from the intentional radiator shall be reduced below the stated values in paragraphs (b)(1) or (b)(2) of this section, as appropriate, by the amount in dB that the directional gain of the antenna exceeds 6 dBi. (i) Systems operating in the 2400-2483.5 MHz band that are used exclusively for fixed, point-to-point operations may employ transmitting antennas with directional gain greater than 6 dBi provided the maximum peak output power of the intentional radiator is reduced by 1 dB for every 3 dB that the directional gain of the antenna exceeds 6 dBi.
So, the limit is 30 dbm (1000 milliwatts), most wireless cards are about 15dbm, which gives us 15 dbm of slack. 24dbi exceeds 6 dbi by 18, so this would be illegal for a point-to-multipoint topology. However, if it was a point-to-point link, that 18dbi of excess gain results in a reduction of only 6dbm of permitted power, so you could use a 24dbm radio (or a little over 200mw) legally. (Though ianal or an rf engineer, so take this with a grain of salt.)
[Code of Federal Regulations] [Title 47, Volume 1] [Revised as of October 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 47CFR15.23]
[Page 693-694]
TITLE 47--TELECOMMUNICATION
CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
PART 15--RADIO FREQUENCY DEVICES--Table of Contents
Subpart A--General
Sec. 15.23 Home-built devices.
(a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use. (b) It is recognized that the individual builder of home-built equipment may not possess the means to perform
the measurements for determining compliance with the regulations. In this case, the builder is expected to employ good engineering practices to meet the specified technical standards to the greatest extent practicable. The provisions of Sec. 15.5 apply to this equipment.
I've used those. They work good but they're a little unwieldy, and probably overkill in this case. (I used a pair of 24dbi parabolics once to test a 5 mile link. It worked, but thoughput wasn't great. In retrospect, the link may have been degraded by the tinting of the window I was transmitting through at one end.)
I've also used panel antennas from superpass, many of which have smaller sidelobes than the parabolics, and are smaller and (usually) cheaper.
At 1000', you might not even need directional antennas (if you have good wireless cards), or you might get away with a directional at only one end.
Thank you, that was the point I was trying to make. By looking at the fastest typists in the world, perhaps we can see if using the dvorak layout represents an advantage that is physically impossible to overcome using qwerty.
Of course, in order to show more conclusively that that's the case, I would need a bit more data, such as the difference between the fastest n qwerty typists and the fastest n dvorak typists, where n is large enough to show a difference between the two populations if one exists.
Just looking at a sample of one may be misleading if she has some other advantage (faster spelling ability, six fingers on each hand, etc..) unrelated to keyboard layout.
I would tend to be suspicious of studies comparing qwerty to dvorak, since most people who learn dvorak learned qwerty first, whereas most qwerty users know only qwerty. Because of qwerty's ubiquity, it's very difficult to make an objective comparison.
I use qwerty and dvorak interchangeably, and am probably slower in both than if I had stuck with qwerty alone, but I find dvorak much more comfortable (and that's something that's much harder to quantify).
According to a quick google search, Barbara Blackburn is the fastest typist in the world and she uses dvorak. That carries more weight than questionable studies in my book, though I would prefer a better reference than a random web link.
Does anyone have data comparing the fastest known dvorak typists to the fastest known qwerty typists?
Blender, as far as I know, is just a design tool, it doesn't actually do any rendering, it just allows you to develop models in a range of formats that you can then throw at a renderer.
No, it has a scanline renderer built in and an optional ray tracer backend called yafray.
I think the most reasonable solution for global illumination is photon mapping. The algorithms are elegant, produce very good output, and (unlike radiosity) are not horribly resource intensive.
It's good to see open source graphics tools. I'm a big fan of pov-ray, but its license is a little too restrictive for my tastes.
Unfortunately, aqsis is not a raytracer, just a scanline renderer, but according to their faq they plan on adding raytracing and global illumination next.
More interesting would be simulating the terraforming of mars. Could we raise the temperature sufficiently by introducing more carbon dioxide into the atmosphere? How about if we used a massive orbital mirror? Or maybe we could grind one of the moons into dust and make an artificial ring to increase ambient light. Inquiring minds want to know.
In other words, some (but not all) taxpayers can file electronicly for free provided they send their personal financial data to some third party they have no reason to trust that has no rational reason to be involved in the first place. (I wonder, what do these free file companies do with all that data?)
Sorry, I'd rather maintain my privacy and use the dead tree snail mail version.
Slashdot Mirror
This is a good question and, last I checked, an open research topic. One workaround is to only accept route advertisements from a trusted set of routers.
Water interferes much more significantly with microwave radio transmissions at above 10 ghz.
Very good game. I like the daimyo system because 1) the game progresses even with 4 or 5 evenly matched players and 2) there's much less of the tedius unit-moving that occurs in axis and allies.
Other cool features: turn order varies from round to round, some tasks are done synchronously is Shogun which were done one-at-a-time in A&A (like buying units), and armies contain hand-to-hand units (samurai, spearmen) and ballistics (riflemen, bowmen). The ballistics get to roll first, and any hand-to-hand units killed can't fight back.
I've always thought it might be fun to play shogun on a risk board, but I've never tried it.
Also, the manufacturer is required to do a background check on all contributers, so that rules out an open source development model.
Mandatory recount of paper ballots is required at 2% of precincts (chosen randomly). This is an improvement, but in my opinion, too low. 98% too low. The electronic count should be used to satisfy those who don't want to wait two weeks to find out who won, but electronic counts should never be considered trustworthy by themselves.
Thanks for the info, I'll look into these. Too bad you can't just pick one up at Fry's.
My understanding of kerberos (please correct me if I'm wrong) is that it's a symmetric key system. Every computer shares a secret key with a central server that handles authentication.
The problem is that the central server, if compromised (or administered by someone of malicious intent), can authenticate anyone as anyone else to anyone else on the network. In other words, you have to trust a third party.
In a public key system, the worst thing the key authority can do is refuse to publish and/or sign your public key. You don't have to trust anyone but yourself.
Do RSA tokens work with linux and/or ssh? It seems like one would only need a modified ssh-agent for remote login and pam module for local authentication. I'd like to be able to walk up to one of my various linux boxes, insert a usb token, and have the machine log me in automatically, and to be able to ssh to other machines without being prompted for my password, and using the token's keypair.
That's interesting. So it's like what ssh does, but if I type a password for some other account by accident, the remote host doesn't capture the password?
I would like to get away from using passwords at all. The average computer user is compelled to remember so many passwords for so many separate accounts, that one usually resorts to writing them all down, or storing them in a text file, or setting them all the same, or using simple dictionary words that are easy to remember (and guess). I would rather use an authentication mechanism that is both secure and easy to use. Any mechanism that uses passwords is neither.
Passwords are insecure, since they may be captured by a keylogger. (I don't think I'm being paranoid to assume the probability of someone covertly installing keylogger software on one of the computers I type an important password on sometime in the next ten years is at least 50%, maybe close to 100%.)
Passwords are inconvienient because one must remember a unique one for each account. I would rather have a small hardware device I could stick in the usb slot to authenticate myself, and never have to remember another password for as long as I live.
It looks like they're just using the usb device as storage for one's keypair. Proper USB tokens, if I understand correctly, do all the encryption on the device and never divulge the private key. As such, they may be used with untrusted computers.
Fair enough, but for my purposes, the danger of someone stealing my usb token is relatively insignificant compared to the danger someone might get root on one of the computers I use and keylog my passwords as I log into accounts on that or another computers. Also, if my token is stolen I will know it. If my passwors are sniffed I won't.
This brings up another question I have: do usb tokens usually come from the factory set to a particular keypair, and can one reset them to a keypair of one's own choosing, or duplicate keys so one has a backup (possibly used to invalidate one's accounts or set a new public key) if one token is stolen or lost?
Passphrases are just long passwords with (usually) low entropy. They still have the same problems... You have to have a separate passphrase for each account, and you have to trust the computer you're using not to log your keystrokes. I would much rather carry around a device that can authenticate me and never have to remember a password again.
Why don't we all just switch to USB tokens for authentication? You have one device that can authenticate you by generating an RSA signature without divulging any information that would allow someone else to pretend to be you. It amazes me that more people don't use these things. I've never used one, but have considered ordering one. Does anyone out there have experience with USB tokens? Is there a good model/brand to buy? Is it easy to get them to work with Linux and ssh? Do any brick-and-mortar stores sell them?
Often, the most authoritative publicly available article on a given subject is in wikipedia, and often these articles have a high page rank.
If someone clicks on a google search result link, and the site is slow (as is sometimes the case with wikipedia), that reflects poorly on google. If google can make a large number of the pages it links to more responsive, it improves user experience, and makes google look good.
So, the limit is 30 dbm (1000 milliwatts), most wireless cards are about 15dbm, which gives us 15 dbm of slack. 24dbi exceeds 6 dbi by 18, so this would be illegal for a point-to-multipoint topology. However, if it was a point-to-point link, that 18dbi of excess gain results in a reduction of only 6dbm of permitted power, so you could use a 24dbm radio (or a little over 200mw) legally. (Though ianal or an rf engineer, so take this with a grain of salt.)
I've used those. They work good but they're a little unwieldy, and probably overkill in this case. (I used a pair of 24dbi parabolics once to test a 5 mile link. It worked, but thoughput wasn't great. In retrospect, the link may have been degraded by the tinting of the window I was transmitting through at one end.)
I've also used panel antennas from superpass, many of which have smaller sidelobes than the parabolics, and are smaller and (usually) cheaper.
At 1000', you might not even need directional antennas (if you have good wireless cards), or you might get away with a directional at only one end.
Thank you, that was the point I was trying to make. By looking at the fastest typists in the world, perhaps we can see if using the dvorak layout represents an advantage that is physically impossible to overcome using qwerty.
Of course, in order to show more conclusively that that's the case, I would need a bit more data, such as the difference between the fastest n qwerty typists and the fastest n dvorak typists, where n is large enough to show a difference between the two populations if one exists.
Just looking at a sample of one may be misleading if she has some other advantage (faster spelling ability, six fingers on each hand, etc..) unrelated to keyboard layout.
I would tend to be suspicious of studies comparing qwerty to dvorak, since most people who learn dvorak learned qwerty first, whereas most qwerty users know only qwerty. Because of qwerty's ubiquity, it's very difficult to make an objective comparison.
I use qwerty and dvorak interchangeably, and am probably slower in both than if I had stuck with qwerty alone, but I find dvorak much more comfortable (and that's something that's much harder to quantify).
According to a quick google search, Barbara Blackburn is the fastest typist in the world and she uses dvorak. That carries more weight than questionable studies in my book, though I would prefer a better reference than a random web link.
Does anyone have data comparing the fastest known dvorak typists to the fastest known qwerty typists?
No, it has a scanline renderer built in and an optional ray tracer backend called yafray.
I think the most reasonable solution for global illumination is photon mapping. The algorithms are elegant, produce very good output, and (unlike radiosity) are not horribly resource intensive.
It's good to see open source graphics tools. I'm a big fan of pov-ray, but its license is a little too restrictive for my tastes.
Unfortunately, aqsis is not a raytracer, just a scanline renderer, but according to their faq they plan on adding raytracing and global illumination next.
How does this compare to BMRT and blender?
More interesting would be simulating the terraforming of mars. Could we raise the temperature sufficiently by introducing more carbon dioxide into the atmosphere? How about if we used a massive orbital mirror? Or maybe we could grind one of the moons into dust and make an artificial ring to increase ambient light. Inquiring minds want to know.
On heavily congested networks with many hidden nodes, rts/cts is your friend.
In other words, some (but not all) taxpayers can file electronicly for free provided they send their personal financial data to some third party they have no reason to trust that has no rational reason to be involved in the first place. (I wonder, what do these free file companies do with all that data?)
Sorry, I'd rather maintain my privacy and use the dead tree snail mail version.