Slashdot Mirror
The Theory of Leech Computing
Phil Frisbie, Jr. writes "I am defining Leech Computing as 'a program running on a client computer without user knowledge that can process data and report back the results, but otherwise does not effect the usability of the client computer and makes no changes to the client'. Leech Computing, Part 1 covers basic theory."
Step #1: Leech off of someone with lots of bandwidth.
what else is Mr & Mrs home users new 2.4Ghz, 510Mb, 120Gb system running XP just purchased to send an AOLgram to missy at college once every weekend, good for?
try { do() || do_not(); } catch (JediException err) { yoda(err); }
A professor in our department hired a research assistant a while ago, who worked for him for about a year. After the assistant left, the professor noticed that his computer was running really sluggish at all hours, but b/c he wasn't really familiar with the system, assumed it was just getting slower with all the data processing algorithms he was running.
A couple of months later, the network admin starts nosing around, and sends the professor an embarassing note asking to take down the web server about hot leather pants from his computer, since it was overloading the network...
Can we use this to create a distributed webserver that where each person who visits the site will serve copies of it? This guy's system can definitely use it! SLASHDOTTED
SIG: HUP
There's also a good page quickly discussing Villain-to-Victim computing. The point is to use correctly configured machines to do things they were not intended to.
Conceptually, I find this interesting. It can run without user notice. The only problem is that it does steal CPU cycles, and as far as I know there is no real way in Javascript (or Java applets) to make the program run only when it isn't competing with other applications. I can imagine that some users might get really upset because you are stealing their computer resources. Because of this, I wouldn't recommend doing this kind of thing without notifying the user and perhaps giving them the option to turn it off. However, I can see some potential uses for this as long as the user is aware. For example, slashdot viewers probably wouldn't mind some leech Javascript working on the latest encryption cracking contest, especially if they got to "share the wealth."
GreyPoopon
--
Why is it I can write insightful comments but can't come up with a clever signature?
Say you're running a 1.5 ghz machine and browsing the web. Chances are, even if you're playing MP3's in the background, you're using less than 5% of your processor cycles. If you could trade another 50% of those cycles you're not otherwise using for the ability to kill ads or for access to a restricted site, Would you?
(I can see it now. 50 to 100 years from now, the Porn Website Coalition has won a Nobel prize for creating a vast distributed network for math intensive problems....)
The problem with this model is that the implimentation of Javascript is slow and horrendously messy. It's brutally inefficient for anything other than the most minor effects carried out in a browser window. I shudder to think of what most browsers would do, given a math-intensive task. FFT's in Javascript anyone?
Unlike the author, I think that Java and/or ActiveX applets will probably see this sort of exploitation first, since they're easier to tune speed out of.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
I recently ran Ad-Aware on my windows box and was surprised to find there were 4 spyware programs installed and running, and remnants of 3 more existed in the registry. And I thought I was being careful...
Somebody please tell this machine I'm not a machine -
When I was an undergrad I did a semester research project on this and identified some of the problems:
http://www.russross.com/cs261/paper.html
I run a dual CPU machine now which generally masks the problem, but even the fastest single CPU systems will suffer noticeable effects once the scheduler falls back to a round robin scheme with weighted timeslice lengths which is essentially what happens once you have two or more CPU bound jobs competing for CPU time.
- Russ
The one thing that surprised me a bit was that the author didn't take advantage of the opportunity to put a bit of leech computing onto his own web page. He mentions (on the second page) that:
Then I remembered that there was, in fact, just such a button on the first page. But when I went back to check, there wasn't actually a Javascript applet there trying to leech a little bit of computing power from me. There wasn't even a cute little message thanking me for checking to see if there was such a Javascript applet. Too bad, he missed a great chance.
There's no point in questioning authority if you aren't going to listen to the answers.
> how could you possibly get data back to the server without the user knowing it
.. " as a close of the top level script tag.
He says refresh and 'tricking' the user are the only ways (on form submits.) Wrong.
dynamic.php:
<script>
data data data
do do
calc calc
var me = answer;
document.write("<script src='http://myserver.com/donate.js?answer=" + encode(me) + "'></scr"+"ipt>");
<\script>
That sends some data to the client, does some client side cals, and sends the data back to my server (although I have to respect the max limit of data one can send via form posts, but its the same with his more obvious methods.)
This is done all the time to count impressions in the advertising world. In fact, in a sense, advertising tracking online is already leech computing in some implementations.
BTW, the
"Old man yells at systemd"