Wikipedia:Reference desk/Archives/Computing/2013 April 14

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April 14

bar codes

i was wondering if a carefully crafted bar code can be used to exploit a scanner. thanks, 70.114.248.114 (talk) 00:16, 14 April 2013 (UTC)

Exploit to do what? OsmanRF34 (talk) 00:48, 14 April 2013 (UTC)

It is conceivable that a badly designed program could mishandle input data and it could cause some exploit. It's a very small amount of data though (relatively; even QR codes are not especially large) so they would need to boostrap larger code to do much interesting. I am sure there have been examples of this (I seem to remember hearing some) but they're exceedingly rare.

If you mean exploit in other ways though, like lower the price, that's a different question. Most basic UPC barcodes only contain a SKU number, and the relevant data is in a database. There have been UPC swapping scams though. Shadowjams (talk) 00:55, 14 April 2013 (UTC)

Why is malware combined with useful downloads?

I recently downloaded some malware while downloading something I actually needed. In this case, it was a program that takes over my search called "Delta Toolbar". I'm usually good with checking every time I'm installing something to see if it's asking me to install whatever program it wants to use to give me extra search bars or overhaul my search what have you, but it does always seem to be related to searching. Is this how those legitimate downloads are able to make money since they're free? Ryan Vesey 01:09, 14 April 2013 (UTC)

• That's what I would guess. I was converting a file type last night online, and apparently had to download an "installer" to convert the file and, in a weaker moment, did not notice that I was downloading something else with the installer. I got this stupid Delta Search thing too, so I assume it has something to do with money. Google it and you will read all kinds of things about it. It took me a half hour to get everything from it off my computer and then I had to uninstall and reinstall Chrome to remove all of the crap it added to that. Go Phightins! 01:16, 14 April 2013 (UTC)

• The toolbar developers pay third parties to bundle them with their products ("pay-per-install"). They make the money back through advertising displayed on the search results page and/or tracking the web sites you visit and selling that information.

Sometimes it's the author of the other product who bundles the toolbar to get some extra revenue, but in this case you will always, I think, be given the option to not install it. (PDFCreator is an example of an open-source product that does this.) However, there are also scammy web sites that redistribute legitimate software from other sites with an adware-installing wrapper. So you should avoid downloading even well-known freeware from random sites. Get it from the official site mentioned in the Wikipedia article, if possible.

(Incidentally, another scam you've probably noticed is ads that appear on software download pages that look like "download" buttons, but actually download something entirely different. If you don't have an ad blocker, it can be hard to find the real download button even on the official download page. So be careful out there.) -- BenRG 02:53, 14 April 2013 (UTC)

I'm almost positive I had the opportunity to stop this one. I opened the install window, and started pressing next like a madman. I was glancing at the windows, but not well enough and I realized I hadn't unchecked a bit of malware. I clicked cancel on the next window hoping I could start over; however, it considered cancel to mean "no, I don't want to install this second bit of malware, go ahead and install everything else now". There was no option to stop the download at that point, even task manager didn't take care of it so I got to watch as my computer installed the malware, it was frustrating to say the least. I do most of my downloading from CNET, but it can get really frustrating because once you click download, it confuses you by throwing up 1000 things with download buttons. Ryan Vesey 03:05, 14 April 2013 (UTC)

You have to be careful about where you are downloading from. Even with legit services, they like to trick you into downloading something else - usually a browser add-on or a program to "scan" your computer for errors. Bubba73 ^{You talkin' to me?} 03:22, 14 April 2013 (UTC)

So I realized I hadn't downloaded what I wanted to at all so I took another look. The download was through adf.ly, which requires you to stare at an ad for 5 seconds and the download link is in the upper right hand corner. There is a much larger download button in the center (the ad) and I went for that one. On another note, a couple years ago I had a popup tell me that my computer had 5 viruses and that I should download a new program to get rid of them. It was a trojan and within a week the computer wouldn't even start. Ryan Vesey 03:33, 14 April 2013 (UTC)

Yes, a couple of I've fallen for that trick of the large download button in the center when the one you want is smaller and in the corner. Now I always try to watch for that. Bubba73 ^{You talkin' to me?} 04:06, 14 April 2013 (UTC)

It is very annoying this crossing the line tat is done on both sides and it just makes for a worse time for all. Personally I consider that I should have a look at somebody's ads if that's the price a person wants me to pay for something, but then you have people with ad blockers who ruin their revenue stream. So then the ads get mean and nasty in their tricks getting people to do things they have not and do not want to agree with. So users have to avoid and be careful of the whole business and treat all ads as malware in the offing. In the end the only winners are large corporations like Microsoft or Apple where people have a good idea what they're getting and just pay the money rather than bothering with all the worry, people without much money are fed viruses. Dmcq (talk) 10:34, 14 April 2013 (UTC)

Even if you download Adobe Reader directly from Adobe, it tries to get you to install McAfee (defaulting to do it), IIRC. Bubba73 ^{You talkin' to me?} 17:47, 14 April 2013 (UTC)

bootstrapping/changing ip address

1: my router is configured to have a dynamic ip, but whenever the lease is up, it does not change. what causes this, and how do i change it manually (if i can)?

2: if someone can give me a short example of python code that bootstraps more complex code, that would be great. thank you, 70.114.248.114 (talk) 03:53, 14 April 2013 (UTC)

Are you losing connectivity to your ISP? As I understand it the lease should never expire as long as you remain connected (assuming the DHCP server is working properly). Looie496 (talk) 04:02, 14 April 2013 (UTC)

You don't generally change addresses when a (DHCP or apartment) lease expires. ISPs use dynamic IPs so that they don't have to pay for IP addresses for people who aren't connected; they have no reason to move you as long as you are connected. If you stay disconnected for long enough the ISP will assign the address to someone else and then you'll get a new one, but I couldn't tell you how long it would take (minutes/hours?).

I don't understand your second question. What kind of bootstrapping do you want? -- BenRG 04:51, 14 April 2013 (UTC)

Note that, as a general rule, ISPs use RADIUS to allocate IP addresses, not DHCP. There's no concept of a "lease". That said, the solution of turning the box that interfaces to your ISP (normally a DSL or cable modem, rather than a straight router) off for a while would get a new IP address.--Phil Holmes (talk) 10:53, 14 April 2013 (UTC)

so, if you have a dynamic ip, it does not change at regular intervals? but only when disconnected for some time? 70.114.248.114 (talk) 00:20, 15 April 2013 (UTC) also, how does an ip scrambler work? 70.114.248.114 (talk) 00:21, 15 April 2013 (UTC)

My IP address changes at random, sometimes in the middle of editing, but this is because I have an intermittent internet connection via a long chain of microwave links, and sometimes this can be very frustrating (though not a problem in Wikipedia because I always edit from my account). Most people's IP addresses are fairly static as explained above. Why would you want to keep changing IP addresses? I trust you are not aiming to avoid blocks. (That's genuine trust, not a snide comment — I've no reason to think that any of your edits have been vandalism.) Dbfirs 07:11, 15 April 2013 (UTC)

thanks for the trust (we need more of that in this world). since some sites use permanent ip blocks, i just wanna be able to change mine in case i find a site that blocked the last person to have my ip. thanks all for the info, 70.114.248.114 (talk) 21:15, 15 April 2013 (UTC)

emacs descent into wordprocessorhood

I've got a new version of emacs (23.2.1) on one of my computers, and it's behaving differently when long lines are wrapped. Control-N and control-P are moving between display lines, not actual lines. That is, if I've got a narrow window containing two lines of text:

The quick brown fox \
jumps over
the lazy dog

where the cursor is under the q of "quick" and the first line is wrapped, control-N moves to the s of "jumps".

That is, it moves to another position on the same line. That's not what control-N is supposed to do! This may be fine for the word processor crowd, but I've been using emacs for (lemme see) 33 years now, and my fingers and lower spinal cord are pretty used to it working the old way.

Presumably there's a mode flag to turn this ghastly new behavior off -- anybody know what it is? —Steve Summit (talk) 12:29, 14 April 2013 (UTC)

You'd never have this problem with vi Rojomoke (talk) 12:32, 14 April 2013 (UTC)

Har har. (I'd just have all those other problems!)

Anyway, if I'd just done a google search, I could have answered my own question.

From http://www.gnu.org/software/emacs/manual/html_node/emacs/Moving-Point.html:

"When a line of text in the buffer is longer than the width of the window [...]

For convenience, C-n and C-p move point by screen lines, as do the equivalent keys <down> and <up>. You can force these commands to move according to logical lines [...] by setting the variable line-move-visual to nil[.]"

"For convenience". Feh. At least you can turn it off. —Steve Summit (talk) 12:37, 14 April 2013 (UTC)

Yes, I think Mark Twain had it right: "It comes fully equipped with all the modern inconveniences." StuRat (talk) 22:30, 15 April 2013 (UTC)

TELESONIC DVD PLAYER TL-2000

Dear friends, From where can I download the USER MANUAL of the TELESONIC DVD PLAYER TL-2000. Thank you very much.175.157.168.56 (talk) 15:33, 14 April 2013 (UTC)

Unfortunately Telesonic is a Chinese company that is involved in a great many things and has no unified web site, so this question is very difficult. It might not be possible. Looie496 (talk) 15:51, 14 April 2013 (UTC)

wikEd Bug Report Submission Help

Hello; I'm in the middle of compiling a bug report about a current incompatibility that wikEd seems to have with MathJax when this is executed via the 'Preview' function. Could any of you guys tell me at which piece of JavaScript I should point Safari 5.0.6's Web Inspector/Error Console to get the entries that I need to submit for this bug report?
Thanks,
— RandomDSdevel (talk) 21:53, 14 April 2013 (UTC)

Um…hello, anybody home? —RandomDSdevel (talk) 19:31, 15 April 2013 (UTC)

Nobody who knows the answer, apparently. Looie496 (talk) 20:44, 15 April 2013 (UTC)

Okay, never mind; I think that I figured it out…I've just never used Safari's debugger before and was confused when it selected one of the extensions that I had enabled instead of some web page code when I started to debug and check for errors. I think, though, that it wants me to step through everything on its list. In that case, should I check the Web Inspector's 'Resources' tab to see what piece of JavaScript gets loaded first and go from there?

— RandomDSdevel (talk) 17:01, 16 April 2013 (UTC)