Wikipedia:Reference desk/Archives/Computing/2012 June 13

= June 13 =

Help me my laptop DVD drive is damaged!!!
It was when I inserted a DVD into my laptop's drive, then suddenly the DVD drive icon dissapears. I cannot open the drive; restarting did not help. Why? 117.5.2.187 (talk) 11:42, 13 June 2012 (UTC)


 * Is your DVD drive one that can be slid completely out of the computer? Maybe when closing the drive you managed to bump something just right to slide the whole drive out a little bit, disconnecting it. If it is a removable drive, try removing it then pushing it back into place. 209.131.76.183 (talk) 13:01, 13 June 2012 (UTC)

Thanks. Seems like my drive work again automatically. 117.5.9.218 (talk) 13:08, 13 June 2012 (UTC)


 * OK, I will mark this Q resolved. StuRat (talk) 21:35, 13 June 2012 (UTC)

Which version of Ubuntu is Wikimedia using for their servers?
Which version of Ubuntu is Wikimedia using? 117.5.9.218 (talk) 13:17, 13 June 2012 (UTC)
 * Does this help? Thincat (talk) 14:28, 13 June 2012 (UTC)

Security check website
What is the recommended way of checking the security of a (my own) website (php,mysql)? I found some tools, but don't know how recommended or useful they are: skipfish, nikto, wapiti, spikeproxy, ratproxy, prewikka, paros. The website should be checked on a test server, pre-use. The tool should run on linux. bamse (talk) 17:54, 13 June 2012 (UTC)

some bookstores have "hacking exposed" by stuart mcclure, joel scambray, and george kurts. its $50 new, but i get it at goodwill for $5. it SHOULD come with a cd-rom with some tools, but some you have to compile yourself, (so you need a compiler.) even without the disk, the book is very useful. hope this helps, 70.114.254.43 (talk) 01:08, 16 June 2012 (UTC)

Wiki having trouble after migration
We run a community wiki, and recently had to switch providers. Our main sysop C&P'ed the entire wiki to the new server, but since then we've run into a number of problems. Notably, images are not displaying correctly, and tables aren't working, either.

If you know what's wrong and can recommend solutions, that would be awesome. If not, I'd be happy to know where I can go for help, or what I can read that will help me to understand the problem myself (right now we really don't know why things aren't working; they worked fine before migrating to the new server).

Here's an example of a problematic page: http://wiktenauer.com/wiki/Andr%C3%A9_des_Bordes

Problems:
 * 1) The thumbnail at the top isn't displaying (even though the raw image is located in the correct place).
 * 2) The wikitable at the bottom isn't rendering properly; it should be a collapsible table, not a standard table.
 * 3) The infobox at the top should be self-contained and allow text to wrap around it.  It's not doing that.

I've tried searching for solutions extensively, but I've been unable to figure out what the problem is. The Jade Knight (talk) 18:17, 13 June 2012 (UTC)


 * If you look at http://wiktenauer.com/wiki/Special:Version, it shows the version of the MediaWiki software that your server is running, and the extensions that are added to it. Most likely you are running different versions of things on the new system than on the old one.  Without knowing more about the old system it is hard to be more specific.  One thing I notice is that your version of MediaWiki is 1.15.3, which was released back in 2010. Looie496 (talk) 18:39, 13 June 2012 (UTC)
 * Looie, that is incorrect. Run some maintenance scripts like update.php. Find them at mediawikiwiki:Manual:Maintenance_scripts. -- J (t)  00:31, 14 June 2012 (UTC)

Two or more people call the same cell phone number at the exact time
(I wasn't sure if this question should go in this section or the "Miscellaneous" section, but I had to pick one of them).

I have two questions regarding this.

My first question (which is, yes, very theoretical, but still technically possible): What would happen if two or more people called the same cell phone number at the exact time (and I mean exact; and, for that matter---just thought of this as I've been typing---, what would happen if two or more people pressed the "Edit" button on the same Wikipedia article at the exact time, as well?)?

Going along with this, lets say (using cell phones as opposed to home phones) "James" calls "Kyle." Kyle isn't able to get to his phone. While James hears ringing and Kyle's phone is ringing, "Bruce" calls Kyle; what would happen---to both Kyle's phone (in one respect, I mean what would happen if you pressed the "talk" button, since two people are calling at once) and James's and Bruce's phone calls (would they continue ringing for them)?

Any help on this would be great. Thanks!

P.S.: Sorry for asking three questions in one section, but I hope you see how they are all very related. — Preceding unsigned comment added by 108.85.4.130 (talk) 19:25, 13 June 2012 (UTC)


 * The resolution of simultaneous access to a shared physical medium is called collision management and is well-studied in network engineering. The exact details of how the "machine" would resolve the collision (that is, how two phone-calls trying to reach the same end-point) would depend on specifics (which type of telephone network).  For a very thorough overview of one type of resolution protocol, you can see how a packet switched network like ethernet works: Carrier sense multiple access with collision detection.  The standard procedure is first to detect that multiple clients are trying to use the network; and then to resolve that simultaneous access by either sharing the medium, or denying access to one client.  Many telephone networks use ethernet and IP at the long-haul layers, so this is actually a very probable resolution in practice.
 * Your follow-on questions are essentially answered in the same way; and ultimately depend on specific details of the software and hardware in use. Nimur (talk) 19:46, 13 June 2012 (UTC)


 * The "Kyle" question is most easily answered: a call made to a number that is already ringing (or is the source of a call that is ringing) is redirected immediately to voicemail (as if the target phone were turned off). For a (single-line) land line target, a busy signal is produced, even if it has call waiting.  (A corollary is that calling your own number produces a busy because your phone is already dialing out and cannot ring.)  The other points are ultimately decided by arbiter circuits at some junction or another.  --Tardis (talk) 04:53, 14 June 2012 (UTC)


 * This is somewhat related to your question(s) and you might be interested in it: code division multiple access. I do not understand much of it and I am not sure if I have the right idea as to what it accomplishes but it allows two radio signals of the same frequency to be distinguished from one another. --Melab±1 &#9742; 22:02, 17 June 2012 (UTC)