Posted by
ryuzaki0
on from the do-it-yourself-toll-gate dept.
MC68040 writes "The guy at this site managed to build something together that's actually quite neat in the way he built it, all hand-crafted system that uses a linux box to unlock his door. Maybe not the coolest of solutions, but actually a pretty good idea as for security in my humble opinion."
I was just reading about barcodes the other day... Check out This if you are interested.
Re:Video store barcode
by
RadioTV
·
· Score: 2, Informative
Actually, a barcode normally doesn't hold that much information. When I worked as a programmer doing manufacturing support, we had trouble scanning anything that had more than 10-12 characters. You have to get pretty creative to be able to cover all the possible things that you might scan. As an example we used the first character to identify what the bar code was for (work order number, sales order number, purchase order number, part number, etc.). Then we could look things up in the appropriate database.
The exception to this is the "two D" barcode (like on a UPS package). If I remember correctly, they can hold ~256 characters (I haven't used them).
-- I have great faith in fools - self confidence my friends call it. - Edgar Allan Poe
Re:And to scan the barcodes
by
MattCohn.com
·
· Score: 2, Informative
The scanner has a CCD; I don't have to slide the barcode.
Funny, and I've implemented something similer with a CueCat, but he would have to slide the barcode if it was a CueCat. Also, barcodes for entry arn't very secure. If anyone gets ahold of your card for 10 seconds, they can make a photocopy and have your security level. A magnetic stripe would have been a better choice for REAL security however, because it takes more elaborate equipment to duplicate.
Re:your house as a semi-permeable membrane
by
jebell
·
· Score: 2, Informative
Rob at Cockeyed.com didn't seem to have problems with his personal bar-code project.
It looks like an inkjet printer, but I could be wrong.
-- This is my sig. There are many like it but this one is mine.
If you looked at the link, you would see that he specifically states, "The door still functions as it did before". He used an electric striker plate, which releases when power is applied to it. So if the power goes out, he just uses a key.
I agree, that page and all the images took about 5 minutes to load on my computer, and I have cable modem. A simple, somewhat reliable solution for the present is to take advantage of google's page cache. Go to http://www.google.com and do a search for "cache:url_to_page" (without the quotes). True, it only gives you text, and not every page is cached in google, but google's servers are fast, and it can be of great help if the original page isn't loading at all.
The front of the house. The windows on the left are to my room.
In my window sits a cheap barcode reader. It's powered by a computer power supply I ripped from an old computer.
Anyone who wants to get into the house can scan a barcode that they carry. A video store gave me a little keychain barcode which I'm using here. The scanner has a CCD; I don't have to slide the barcode. The scanner actually has a beeper that I can control from the computer. You can hear it beep from outside the window.
Here's the driver circuit I slapped together for the barcode reader. It's just a MAX232 chip that converts CMOS/TTL levels to the RS232 spec. The output connects to the serial port of one of my Linux boxes. That box runs a trivial python program to read a packet from the serial port and send it via TCP/IP to another computer in the house.
The receiving computer is connected to this K8000 experimenter board. I2C chips on this board . If your barcode was on the list of allowed keys, I raise output 7 on this board for 6 seconds. Input 6 (the right-hand illuminated LED) shows that the door was closed when I took this picture. See below for how I sense if the door is opened or not.
Some successful reads.
When the K8000 board raises the right output signal, this driver circuit sends 24VDC to the door strike, shown below.
In this electric strike is a solenoid that relaxes the part of the strike that was holding the door closed. The door still functions as it did before, but now I have an additional way to allow the door to open.
This is the top of the door frame, where I have wedged a reed switch into the wood. There's a magnet on top of the door that closes the switch when the door is closed (hence the turned-on LED in the picture above).
Slashdot really, truly, utterly needs to have a local cache of the pages it references. It's getting to where Slashdotting is as bad as a denial of service attack - and that's a terrible thing to inflict on *anyone*.
Slashdot should cache pages to prevent the Slashdot Effect!
Sure, it's a great idea, but it has a lot of implications. For example, commercial sites rely on their banner ads to generate revenue. If I cache one of their pages, this will mess with their statistics, and mess with their banner ads. In other words, this will piss them off.
Of course, most of the time, the commercial sites that actually have income from banner ads easily withstand the Slashdot Effect. So perhaps we could draw the line at sites that don't have ads. They are, after all, much more likely to buckle under the pressure of all those unexpected hits. But what happens if I cache the site, and they update themselves? Once again, I'm transmitting data that I shouldn't be, only this time my cache is out of date!
I could try asking permission, but do you want to wait 6 hours for a cool breaking story while we wait for permission to link someone?
So the quick answer is: "Sure, caching would be neat." It would make things a lot easier when servers go down, but it's a complicated issue that would need to be thought through in great detail before being implemented.
They could easily implement some kind of opt-in thing where you put a META tag in your web page telling Slashdot that you grant them explicit permission to mirror the site for (say) a week after mentioning it - so Slashdot would have no legal/copyright come-backs.
You're a genius! Oh...wait...no... You just haven't read the FAQ:
Is it possible to have META tags that Slashdot looks for in a story link before allowing it to be submitted/posted? Many times a server can't handle the load of a Slashdotting. So can the site have tags to prevent it from being added to a Slashdot story?
Not inconceivable, but I don't really think it's worth the work. Most of the sites that are Slashdotted are prepared for it, and the sites that get smashed usually are caught completely off guard; they wouldn't know of this mysterious opt-out meta tag. (See also Caching Slashdot Stories).
It's not rocket science to configure Apache to handle a Slashdotting. I've been hit three times in the past five years. Every time, my little 333MHz eMachine has done just fine. I just followed the instructions in the Apache guide. This guy took another fine route -- he took his pages off-line for the time being. Either route works.
People who put up websites should recognize that people are going to look at it. Sometimes, a lot of people might look at it, as a result of a link from Slashdot or any of hundreds of other sites. People who bitch and moan about being linked to from Slashdot remind me of the companies who whine when people link to "confidential" webpages -- guess what, if it's on the web, it's not confidential.
First of all, as you see on this guy's site now, he's taken it offline due to the load. I've sent him an email explaining that there woulden't be a slashdot effect if nothing was posted on slashdot but that I'm sorry anyway. Second of all, as for security. I was not considering this as a high-level mumbo-jumbo super-secure system but I'm just of the opinion that it was pretty neat (atleast more neat that just sliding your magnetic stripe card throught a reader) and a easy way to provide users with time-limited access not for it to be a failsafe system =) It's just cool.
Slashdot Mirror
Here
I was just reading about barcodes the other day...
Check out This if you are interested.
Actually, a barcode normally doesn't hold that much information. When I worked as a programmer doing manufacturing support, we had trouble scanning anything that had more than 10-12 characters. You have to get pretty creative to be able to cover all the possible things that you might scan. As an example we used the first character to identify what the bar code was for (work order number, sales order number, purchase order number, part number, etc.). Then we could look things up in the appropriate database.
The exception to this is the "two D" barcode (like on a UPS package). If I remember correctly, they can hold ~256 characters (I haven't used them).
I have great faith in fools - self confidence my friends call it. - Edgar Allan Poe
The scanner has a CCD; I don't have to slide the barcode.
Funny, and I've implemented something similer with a CueCat, but he would have to slide the barcode if it was a CueCat. Also, barcodes for entry arn't very secure. If anyone gets ahold of your card for 10 seconds, they can make a photocopy and have your security level. A magnetic stripe would have been a better choice for REAL security however, because it takes more elaborate equipment to duplicate.
It looks like an inkjet printer, but I could be wrong.
This is my sig. There are many like it but this one is mine.
If you looked at the link, you would see that he specifically states, "The door still functions as it did before". He used an electric striker plate, which releases when power is applied to it. So if the power goes out, he just uses a key.
RTFL
I agree, that page and all the images took about 5 minutes to load on my computer, and I have cable modem. A simple, somewhat reliable solution for the present is to take advantage of google's page cache. Go to http://www.google.com and do a search for "cache:url_to_page" (without the quotes). True, it only gives you text, and not every page is cached in google, but google's servers are fast, and it can be of great help if the original page isn't loading at all.
Google Cached Site text with photos removed:
The front of the house. The windows on the left are to my room.
In my window sits a cheap barcode reader. It's powered by a computer power supply I ripped from an old computer.
Anyone who wants to get into the house can scan a barcode that they carry. A video store gave me a little keychain barcode which I'm using here. The scanner has a CCD; I don't have to slide the barcode. The scanner actually has a beeper that I can control from the computer. You can hear it beep from outside the window.
Here's the driver circuit I slapped together for the barcode reader. It's just a MAX232 chip that converts CMOS/TTL levels to the RS232 spec. The output connects to the serial port of one of my Linux boxes. That box runs a trivial python program to read a packet from the serial port and send it via TCP/IP to another computer in the house.
The receiving computer is connected to this K8000 experimenter board. I2C chips on this board . If your barcode was on the list of allowed keys, I raise output 7 on this board for 6 seconds. Input 6 (the right-hand illuminated LED) shows that the door was closed when I took this picture. See below for how I sense if the door is opened or not.
Some successful reads.
When the K8000 board raises the right output signal, this driver circuit sends 24VDC to the door strike, shown below.
In this electric strike is a solenoid that relaxes the part of the strike that was holding the door closed. The door still functions as it did before, but now I have an additional way to allow the door to open.
This is the top of the door frame, where I have wedged a reed switch into the wood. There's a magnet on top of the door that closes the switch when the door is closed (hence the turned-on LED in the picture above).
Closeup of the reed switch in the wood.
###
-Mac Refugee, Paper MCSE, Linux Wanna-be
Read the FAQ: They could easily implement some kind of opt-in thing where you put a META tag
in your web page telling Slashdot that you grant them explicit permission to mirror the site for (say) a week after mentioning it - so Slashdot would have no legal/copyright come-backs.
You're a genius! Oh...wait...no... You just haven't read the FAQ
People who put up websites should recognize that people are going to look at it. Sometimes, a lot of people might look at it, as a result of a link from Slashdot or any of hundreds of other sites. People who bitch and moan about being linked to from Slashdot remind me of the companies who whine when people link to "confidential" webpages -- guess what, if it's on the web, it's not confidential.
-Waldo Jaquith
First of all, as you see on this guy's site now, he's taken it offline due to the load. I've sent him an email explaining that there woulden't be a slashdot effect if nothing was posted on slashdot but that I'm sorry anyway.
Second of all, as for security.
I was not considering this as a high-level mumbo-jumbo super-secure system but I'm just of the opinion that it was pretty neat (atleast more neat that just sliding your magnetic stripe card throught a reader) and a easy way to provide users with time-limited access not for it to be a failsafe system =) It's just cool.
My 0,5 cents.