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Wikipedia:Reference desk/Archives/Computing/2010 August 21

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August 21 edit

Would this power supply be sufficient for this build? edit

ASUS Crosshair IV Formula Motherboard - AMD 890FX, Socket AM3, ATX, DDR3, USB 3.0, RAID, SATA 6.0GB/s

AMD HDT90ZFBGRBOX Phenom II 1090T Black Edition Six Core Processor - 3.20GHz, 6MB Cache, 2000MHz (4000 MT/s) FSB, Retail, Socket AM3, Processor

Thermaltake CLP0564 Frio Dual 120mm Universal CPU Cooler - LGA1366, LGA1156, LGA775, AM3, AM2+, AM2

Western Digital WD10EARS Caviar Green Hard Drive - 1TB, 3.5", SATA 3G, 64MB Cache, GreenPower

XFX HD585XZABC Radeon HD 5850 Black Edition Video Card - 1GB GDDR5, PCI Express 2.0, CrossFireX, DirectX 11, HDMI, Dual DVI x2 Planning to crossfire.

Corsair CMT8GX3M4A1866C9 Domintor GT Dual Channel 8192MB PC15000 DDR3 Memory - 1866MHz, 4x2048MB, 9-9-9-24

Cooler Master RC-942-KKN1 HAF X ATX Full Tower Computer Case - ATX, 230mm Red LED Fan, USB 2.0/3.0, 9x Expansion Slots. *Supports XL-ATX, 4-way SLI and Quad Crossfire X

Would this power supply power this build? XFX 850W Black Edition Modular Power Supply - ATX, 80 Plus Silver, 135mm Fan, Single Rail, NVIDIA SLI, ATI CrossFire Ready

Any help would be much appreciated:) —Preceding unsigned comment added by 99.155.19.25 (talk) 00:45, 21 August 2010 (UTC)[reply]

You know Caviar Green drives are not good as boot drives right? You are spending quite a bit of money here, so might as well get a SSD. Get a Sandforce or Intel. If you insist on using HDD, at least get a F1 or something. 121.72.208.23 (talk) 02:42, 21 August 2010 (UTC)[reply]
OT, but my recommendation for SSDs applies equally whether you are buying a 6 core like OP or an el-cheapo 2 core Athlon X2 250 like me. It really does make a huge difference to the computer's responsiveness. 121.72.208.23 (talk) 02:49, 21 August 2010 (UTC)[reply]

want to edit the boot.ini edit

This is is my boot.ini on WinXP machine. I want to remove the OS selector window appearing each time I boot. There is only one OS currently. What should I edit out to do that? 

[boot loader]
timeout=3
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft... 
c:\grldr="Start GRUB"

--117.204.83.220 (talk) 04:34, 21 August 2010 (UTC)[reply]

Remove the c:\grldr="Start GRUB" line and then boot from your Windows XP installation CD. Run the recovery console and type fixboot and press ENTER. Then type fixmbr and press ENTER. Besides changing boot.ini Linux also edits the MBR on your drive. So, simply changing the boot.ini file isn't enough.--Best Dog Ever (talk) 04:47, 21 August 2010 (UTC)[reply]
Umm, no. If there's a C:\grldr="Start GRUB" line present in boot.ini, then the MBR and boot sector have not been altered by Linux. If GRUB would have been installed to the MBR, there would be no need for the line in boot.ini, as GRUB would start immediately. The line in question is to allow the XP boot manager to pass control to GRUB (GRUB4DOS, in this particular instance). -- 78.43.71.155 (talk) 17:50, 21 August 2010 (UTC)[reply]
So, the last line could be safely removed? In case of boot failure a fixmbr would fix it? --117.204.86.159 (talk) 18:47, 21 August 2010 (UTC)[reply]
There simply will not be a case of boot failure by removing that line. -- 78.43.71.155 (talk) 19:52, 21 August 2010 (UTC)[reply]
True. I removed the last line and it now boots without the OS selection screen. Thanks. --117.204.84.201 (talk) 11:29, 22 August 2010 (UTC)[reply]
Trust in the knowledge of your fellow Jedis Wikipedians you must have, young padawan grasshopper. -- 78.43.71.155 (talk) 19:59, 23 August 2010 (UTC)[reply]

php functions edit

been searching for a php function that when supplied with an array key would return its current array position, i mean when keys are integers but not the same as the positions in the array. and also one that would set an array current position to the specified pos so when you do foreach for expample it would start right from there I also need only php-built in ones not written by yourself

thnx —Preceding unsigned comment added by 85.26.241.39 (talk) 06:59, 21 August 2010 (UTC)[reply]

Is array-search what you need? -- Finlay McWalter ☻ Talk 11:39, 21 August 2010 (UTC)[reply]
I don't think so — if I understand correctly (and man, it would help to give more concrete examples), he has an array like this:
array (
2 => apple,
4 => orange,
5 => grape);
And what he wants is to say "where is 4?" and it will say, "oh, 4 is in position #2 out of 3 in the array." I don't think there's a built-in function that can do that. You will either have to write one (which could be quite slow depending on how big your dataset is), or you will have to re-work your code so it doesn't require knowing that information. I suspect the latter because you can't start a foreach from an arbitrary position — you can't set the array pointer arbitrarily, you have to start from the beginning and advance it either with "each" or "next" statements.
The only way to do more or less what you want that I can see is to dump the keys into an array (array_keys), then use array_search on that array to find the position, and then just reference the original array by the key name. --Mr.98 (talk) 14:54, 21 August 2010 (UTC)[reply]
A short function that does what you want is here. But I remind you that you can't start a foreach arbitrarily — it always starts from the beginning. What you could do is extract the part of the array you want to traverse into a new array, so that the beginning is where you want it, I guess. All of this sounds very inefficient to me, though.
function key_pos($input_array, $key) {
	$key_array = array_keys($input_array);
	return array_search($key, $key_array);
}
--Mr.98 (talk) 15:10, 21 August 2010 (UTC)[reply]
And here is an example that integrates it with your traversing of the array (which can't be done with foreach):
$arr = array (2=>"apple", 4=>"orange", 5=>"banana", 10=>"grape");

$key_array = array_keys($arr);
$key_orange = array_search(4, $key_array);

for($i=$key_orange;$i<count($arr);$i++) {
	echo $key_array[$i]."=>".$arr[$key_array[$i]]."\n";
}
That will output "orange, banana, grape", skipping "apple". I don't know if this is faster than just iterating over the whole thing with a foreach and ignoring the values that come before your desired key. --Mr.98 (talk) 15:14, 21 August 2010 (UTC)[reply]

Ubuntu home directory and settings in kde edit

I just reinstalled ubuntu and I thought that copying over my previous home directory would restore my old settings. That doesn't seem to have happened at least with respect to kde. Are these settings stored somewhere else? —Preceding unsigned comment added by 166.137.142.134 (talk) 09:00, 21 August 2010 (UTC)[reply]

Are you sure its KDE not Gnome? Ubuntu uses Gnome by default (Kbuntu is a version of Ubuntu that uses KDE by default). KDE's configuration is stored in ~/.kde3 where ~/ is your home directory. Some programs hide files starting with a . by default. CS Miller (talk) 11:05, 21 August 2010 (UTC)[reply]
Exactly which settings are you missing? The KDM login theme or the user icon shown by KDM during login, maybe? -- 78.43.71.155 (talk) 18:33, 21 August 2010 (UTC)[reply]

Date modified in vista edit

Why is "date modified" not a default category to sort your files by in Windows Vista? It was in earlier versions of Windows. It's totally annoying that it isn't. You can still apply that category to a folder, it just takes longer.--Hsardoft (talk) 09:04, 21 August 2010 (UTC)[reply]

It depends what files Vista thinks are in the directory. If it believes there are photos, then it doesn't display Date Modified. If it thinks the contents are "All Items" then Date Modified is a categroy. You can get Data Modified to display in a folder by Right Click, Customize this folder and set it to All items. Annoys me too. --Phil Holmes (talk) 09:48, 21 August 2010 (UTC)[reply]

Fake email address edit

Doing a bit of reading about Phishing I know it is fairly straight forward to do a fake web page for login purposes, but is it also possible that a fake email address could be set up, I know a lot of companies use the standard firstname.lastname@companyname.com so what I was wondering could someone set up an email address using this format for instance joe.bloggs@bankofengland.co.uk, thanks Mo ainm~Talk 14:06, 21 August 2010 (UTC)[reply]

Email protocol allows you to use ANY email address when you send an email. It is very very very easy. In your email program, you will see a setting for "my email address". Set it to "president@whitehouse.gov" and send an email to your friends. There is no check to ensure that is your email. Spammers tend to use millions of email addresses and they randomly select one as the "from" and use that to send email to millions of others. Whomever has that from is then inundated with thousands of "failure" responses. -- kainaw™ 15:16, 21 August 2010 (UTC)[reply]
To clarify what Kainaw said - the From: and Reply-To: fields in an email address are about as reliable as the return-to address on the outside of a paper envelope - the sender can put on whatever they want.
If you want to setup a fake receiving email address it is just as easy as setting up a fake web site.
To set up a site, real or fake you -
  • Request a static IP number from an ISP, you have no control over the IP number, as it will be allocated from your ISP's pool.
  • Request a DNS name from a registrar. This gets you something like .example.com. You have full choice of this, except some TLD are restricted, for example .gov and .mil are only allowed for use by the US government.
What you do with the domain is up to yourself, however you would normally -
  • Set up a computer with that the IP number, either at home or in a colocation centre.
  • Install a DNS server on the computer, have the registrar delegate all queries for .example.com to your computer.
  • Set up the primary name of the computer as www.example.com.
  • In your DNS server, set up an Address alias smtp.example.com to your computer; it is now known as "smtp.example.com" as well.
  • In your DNS server, set up an MX DNS record (Mail eXchange), this is used for delivering email to @example.com, point it at smtp.example.com
  • Set up a mail server and www server.
This is what you do for a legitimate server. Since you are in full control of all addresses under the .example.com, and domains are resolved right-to-left, you can you can set up a fake site at whitehouse.gov.example.com. To do this you would -
  • In your DNS server, set up an Address alias www.whitehouse.gov.example.com, aliasing it to www.example.com
  • In your DNS server, set up an MX DNS record @whitehouse.gov.example.com, pointing it to smtp.example.com
  • Modify the www and mail server configurations so they will accept queries to whitwehouse.gov.example.com as well as the primary ones set up above
You can now send and receive email from barack.obama@whitehouse.gov.example.com which has nothing to do with barack.obama@whitehouse.gov
Note that this is fairly easy to do, at technical level.
However, impersonating Barack Obama might be illegal, and is likely to get you extradited to the US.
CS Miller (talk) 15:52, 21 August 2010 (UTC)[reply]
Thats great thanks so even if the email comes from what looks like, in your case Csmiller, Barack Obama, just because it follows the correct format it could still be a fake address, thats exactly what I was wondering. Follow on question say I set up the email address barack.obama@whitehouse.gov and their was a legitimate email address for the American president using the same, when I typed in the address who would get the email? The fake President or Real? Mo ainm~Talk 15:59, 21 August 2010 (UTC)[reply]
The anatomy of an email address:
username @ subsite  .   site  .  ext
     |       |           |        \__ Top level
     |       |            \
     |        \            \_________ Second tier
     |         \
     |          \____________________ Third tier
     |
     \________________________________ Username


In order to decide where an email goes, the url is parsed from right to left; and as CSMiller has explained, whoever controls any tier has total control of the names of the subtiers from that point on. So, whitehouse.gov is controlled by the government; but whitehouse.gov.nimur.com is controlled by whoever controls nimur.com. The parse-order precedence is right-to-left; so if you want to guarantee identity, you need to make sure that the top-most (right-most) tiers are trusted (i.e., that you are sure they are who they say they are). Nimur (talk) 16:09, 21 August 2010 (UTC)[reply]
You can't "Set up" an account that is exactly "barack.obama@whitehouse.gov" because you don't control the server "whitehouse.gov". You can send emails with forged "From" addresses. If someone replies to the forged email, they'll send an email to whatever the return address is. This is exactly as if you wrote "B. Obama, 1600 Pennsylvania Avenue, Washington, D.C." in the upper left hand corner of an envelope. The person who got the envelope might be fooled into thinking it was from the president, but if they wrote back to that address it would go to the white house, not to the prankster who wrote the letter. APL (talk) 05:47, 22 August 2010 (UTC)[reply]
Plain old SMTP basically doesn't care what you claim to be sending it from. I remember back in the early 2000s when the UC Berkeley SMTP server was basically unsecured in this way, and you could set up your e-mail program with any "From" address you wanted, and it would send just like any other, as long as you were on the campus network. (You couldn't receive mail arbitrarily, but you could send it.) At some point I am pretty sure they switched to requiring authentication, which cuts down on that sort of thing a bit. --Mr.98 (talk) 22:12, 21 August 2010 (UTC)[reply]

Ipone 4 Apps edit

Is it true that if I were to purchase an Iphone4 Unlocked PAYG, I would be able to access less apps than I would on a contract phone? —Preceding unsigned comment added by 85.211.141.84 (talk) 14:41, 21 August 2010 (UTC)[reply]

The purpose of unlocking a phone is so you can access apps that would otherwise be locked out...so I'd say the answer is no.Smallman12q (talk) 01:50, 22 August 2010 (UTC)[reply]
I don't think the OP is talking about jailbreaking his phone, but about buying one that isn't tied to a certain service provider (e.g. AT&T). Thanks, 99.224.10.2 (talk) 19:55, 23 August 2010 (UTC)[reply]

Malware through video codec? edit

Is it currently possible to be infected with malware through a video codec? --Belchman (talk) 15:03, 21 August 2010 (UTC)[reply]

From this link in 2008 it appears it is. Mo ainm~Talk 15:07, 21 August 2010 (UTC)[reply]
Not really... that link just says that someone may send you a trojan whose filename appears to be a video codec - which isn't anything new. --Belchman (talk) 16:39, 21 August 2010 (UTC)[reply]
Yes...its possible. A Video codec is nothing more than a library (computing)/API. Your question isn't specific in that the video codec is delivering the malware or if the contents processed through the video codec are delivering it...but its possible. There are plenty of trojan codecs...and codecs can be exploited via content processed through them via buffer flow exploitations which allow malicious code to be executed such as this one with Xvid and this one with MP3s. Hope this answers your question.Smallman12q (talk) 23:05, 21 August 2010 (UTC)[reply]
The way I wrote my question makes it almost impossible to understand. My apologies. I meant that if it is possible to get malware by watching a video you just downloaded through a torrent, p2p or whatever. Thank you :) --Belchman (talk) 00:54, 22 August 2010 (UTC)[reply]
Depends on the source...though most online web players/hosts such as hulu, megavideo, youtube, etc. are virus free. For actual p2p downloads...it could happen if you download from a malicious source.Smallman12q (talk) 01:48, 22 August 2010 (UTC)[reply]

Student laptop webcam surveillance edit

What steps can students take to avoid webcam surveillance of the sort described in Blake J. Robbins v. Lower Merion School District?
—Wavelength (talk) 15:17, 21 August 2010 (UTC)[reply]

Put masking tape over the camera lens ;D --71.141.97.250 (talk) 16:14, 21 August 2010 (UTC)[reply]
Taping over the webcam is mentioned here, on page 41.—Wavelength (talk) 19:32, 21 August 2010 (UTC)[reply]
Own and operate your own equipment, and only install trusted system-software. Nimur (talk) 16:24, 21 August 2010 (UTC)[reply]
Atleast 55,603 photographs; there would probably be around 1,390 images of students in a state of undress in that lot!! What were they trying to do - start a kiddy porn shop? And how can anyone be absolutely certain that none of the photographs snapped of students in various states of undress were not sold to perverts and pedophiles? If pictures of even one student was sold to even one pedophile, the student could be at risk from that pedophile!! One would wonder how this could happen in America. Rocketshiporion

Ignore my earlier outburst - here's what to do on a Windows computer to disable your webcam, so that it cannot be activated by software.

  1. Step 1: Click the Windows button (or press the Start button on your keyboard), then right-click Computer.
  2. Step 2: A menu will open - select Manage on this menu. If you are not logged in as the Administrator, you may be requested for a password or for confirmation - type in the password then press enter, or provide confirmation.
  3. Step 3: The Computer Management Console window will open. Click Device Manager (located on the menu on the left under System Tools).
  4. Step 4: Locate and expand the Imaging Devices hierarchy. The webcam will appear here under the name Integrated Webcam, USB Video Device or something else similar.
  5. Step 5: Right-click the name of the webcam, and select Properties from the menu which appears.
  6. Step 6: The Properties box will appear. Select the Driver tab, and click the Disable Device button. If a passsword or confirmation is requested, type in the password and press Enter, or provide confirmation.
  7. Step 7: Click OK to close the Properties box. Important: Do not click Cancel, as this will undo your changes.
  8. Step 8: At the top-left corner of the Computer Management Console window, click File then select Exit from the menu which appears.
  9. Note: If you would like to uninstall your webcam instead of disabling it, in Step 7, click the Uninstall button instead of the Disable Device button. Important: If you uninstall your webcam instead of disabling it, you will have to scan for hardware changes then manually reinstall the webcam's driver(s), if you should ever want to use the webcam again in future.

Rocketshiporion Sunday 22-August-2010, 12:48am GMT

I had assumed the school district would not just hand the admin password over to the students. Comet Tuttle (talk) 20:08, 23 August 2010 (UTC)[reply]

Doubling up router cables edit

I have a router with four RJ45 sockets on the back. Is there any way to connect more than four devices to the router by cable, or do I need a bigger router with more sockets? 86.147.153.107 (talk) 17:41, 21 August 2010 (UTC)[reply]

Add another router or hub to it; use a normal or cross piece of Cat5 RJ45 cable to connect it to your main router. NB, what is normally called a 'router' for home use has a 4-port ethernet hub, a WiFi access point and a ADSL modem built in. The second router does not need WiFi or ADSL. Most cable-modems' routers are rated at 100Mbit/s; if you often transfer data between two local computers you should get a 1gigabit/sec ethernet router and connect as many of your computers as possible to it. CS Miller (talk) 18:01, 21 August 2010 (UTC)[reply]
A switch will do (adding another router doesn't really make sense, that'd be overkill, and hubs are basically outdated devices, switches are what is used these days). Think of it as an extension cord, just for network devices rather than for power. -- 78.43.71.155 (talk) 18:21, 21 August 2010 (UTC)[reply]
See Network switch. Equisetum (talk | email | contributions) 21:32, 21 August 2010 (UTC)[reply]
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