Wikipedia:Reference desk/Archives/Computing/2013 February 3

= February 3 =

Static IP Address
I have a Rikomagic MK802 mini Android computer that plugs into my TV's HDMI port and turns my TV into something like an Android tablet. The device is connected to my home Wifi network. I also have another Android tablet that I use as a mouse/keyboard to control the MK802. They communicate via my home Wifi network.

The way I connect the two device is through this app where I enter the IP address of my MK802. However, each time I shutdown the MK802, it receives a slightly different IP address. For ex, one time it might be 192.168.0.4, but when I restart it becomes like 192.168.0.5. Is there a way for me to make the IP address static so that I can enter in the same IP thorugh my tablet each time, rather than finding its new IP address?

I have a time warner Ubee Modem/router if that matters.

Thanks! Acceptable (talk) 01:52, 3 February 2013 (UTC)


 * I don't know about the Rikomagic device specifically, but standard Android allows you to set static IPs on per-network basis. You can long-press on a network on the Wi-Fi screen and select "modify network." From there, you can check "advanced options" and switch IP settings from DHCP to static. The settings there should be populated if you're already connected to the network, so you should be able to just save that in order to keep your current IP address. — daranz [ t ] 04:41, 3 February 2013 (UTC)
 * If you have administrative access to your cable modem, then it's probably better to set a fixed IP address for your device there (it will be in the DHCP settings). That way, your device still uses DHCP to get an address, and (unless Daranz's solution is per-network), the device will still work on other networks. If you use Daranz's solution, then pick a high address, I'd start at 192.168.0.254 and work down for other devices - otherwise the cablemodem's DHCP server might give the same address to another device. CS Miller (talk) 06:34, 3 February 2013 (UTC)
 * Note that many routers only use a reduced range, usually starting higher up, e.g. 127 for a their DHCP assignments so it's often not necessary or even wise to start higher up. It also depends how assignments are carried out, not all devices hand out IPs sequentially. Also some devices use 254 for the router by default, so it's probably not the best idea to fix this to some other device if you don't already know it isn't used. Edit: Admittedly I just remembered the info the OP provided suggested it is given out sequentially and also that it does start at 2 or something similar. Nil Einne (talk) 09:29, 3 February 2013 (UTC)

How do I set the static IP via my modem control panel? There's a panel under "Gateway" that's called "DHCP static lease," is this the right place to assign a static IP? Also, sorry my knowledge of network is not so strong, but is there a reason why all routers seem to default to a dynamic IP address vs a static one? Is there some sort of advantage to this that I would be getting rid of when I switch my device to a static IP? Thanks! Acceptable (talk) 18:46, 3 February 2013 (UTC)


 * Acceptable, that sounds like it's for the ADSL-side of the modem, not the LAN side. There should be a list of "attached devices" somewhere; this should show each device, by their MAC address. This is six hex-pairs, separated by colons, like 01:23:45:56:78:9a. There should be on this page, or somewhere else, a page that allows you to assign a fixed IP address to each MAC address. You might need to assign a nickname to the MAC, and then a IP to the nickname. You can see how to view your devices address (from the device) on, it appears to start 00:26 CS Miller (talk) 20:16, 3 February 2013 (UTC)

How many Korean Wikipedians are out there?
Any idea? meta:Editor Survey 2011 is not very helpful for countries below the Top 10. --Piotr Konieczny aka Prokonsul Piotrus&#124; reply here 17:31, 3 February 2013 (UTC)
 * You could check the active users list, if it exists on the Korean Wikipedia. The English one is listed at Special:SpecialPages.  I don't know what it is in Korean.  ActiveUsers give all editors who did something in the last month.  ListUsers is every account.  RudolfRed (talk) 19:03, 3 February 2013 (UTC)
 * Special:Statistics also has a numerical count of users who have made an edit in the last 30 days. Here's a link to kowiki's Special:Statistics in English — daranz [ t ] 19:29, 3 February 2013 (UTC)
 * Thanks, this is quite helpful! --Piotr Konieczny aka Prokonsul Piotrus&#124; reply here 19:45, 3 February 2013 (UTC)

4G LTE vs Wifi; battery usage?
I have a Verizon, Android smartphone with 4G LTE. Does LTE use more battery than Wifi? If I am in a situation where I have an open Wifi network and good LtE connection, should I turn on Wifi in order to save battery when I want to use data?

Conversely, I heard that WiFI actually uses more battery when there is no open network and it is constantly scanning. Is this true? In a situation where I am walking down the street with no open Wifi networks, should I turn off Wifi in my phone settings in order to save battery? Acceptable (talk) 18:42, 3 February 2013 (UTC)
 * If LTE is sparse where you are your device may have to send more power to reach a remote cell site. A local WiFi should consume less power as you should not have to transmit so much to reach it.  But sure turning off WiFi will save energy if there is no available networks.  Also disabling hidden networks on your device will stop it polling for them when they are nowhere near. Graeme Bartlett (talk) 10:36, 4 February 2013 (UTC)

Configuring firewall or RDP server
My ISP provided me with a Huawei HG655b "home gateway". I would now like to configure the device's built-in firewall to let me use port 3389. This is so that I can use xrdp to display a Linux desktop on my Windows PC using the remote desktop connection. Unfortunately, the Huawei device seems to only let me configure fixed port numbers for a few applications - http, DNS, SMTP and a few others - not RDP, not telnet/SSH (which I've just realised might have been the cause of a problem I had with telnet some months back). Can the Huawei be configured in some way, without resorting to turning off the firewall which I don't think is a good idea? Alternatively, could I configure xrdp so it would work with a different port, one that the firewall does let pass? Astronaut (talk) 19:06, 3 February 2013 (UTC)
 * I found this:, which says you can set the port number in xrdp.ini file. RudolfRed (talk) 19:10, 3 February 2013 (UTC)

In general, is using a port number for something else a good/safe idea? For example, could I configure xrdp to use port 21 (normally FTP) without it messing up something else? Astronaut (talk) 21:02, 4 February 2013 (UTC)

Sound files
In Mac OS X the computer has sound files that accompany certain functions such as emptying trash, duplicating files, or dropping files into trash. How could I locate these files on the computer? Thank you. Bus stop (talk) 19:49, 3 February 2013 (UTC)
 * In the Finder, type "audio", then select "Audio" from the "Kinds" menu that pops up. Then look through the results. Most are in /System/Library/Sounds/. You can also search for ".aiff". --Stephan Schulz (talk) 00:19, 4 February 2013 (UTC)
 * Thanks. I found a bunch of them. I actually haven't found the three I was looking for. I will keep looking. That was helpful. I now think I sort of know where to go rooting around for such files. Bus stop (talk) 03:22, 5 February 2013 (UTC)

3D scanning
I have a Canon EOS 500D and would like to try making 3D models for 3D printing using it in a Structured-light 3D scanner system. I found this pdf but it is either over my head or doesn't cover the software and camera connections for a DSLR. Is there any easy (and free) software out there to do this function? The mirrors, DLP projector, and calibration I will worry about once I figure out if my camera will work. 3D printing is getting popular in Hackerspaces and I don't think the one here in Edmonton has a printer yet. Making models of objects seems to be the first step and I am wondering if there is an easy way to make them with a DLSR to scan objects. I am using Win7 and I think Kinect software may work with my Canon DLSR but haven't found details on the hook-up and configuration anywhere.--Canoe1967 (talk) 19:51, 3 February 2013 (UTC)


 * I recall seeing demos of Kinect being used for 3D scanning, yes. http://www.david-laserscanner.com/ is one free package that requires only a camera and a laser pointer. ¦ Reisio (talk) 23:16, 3 February 2013 (UTC)
 * Thank you. They use a webcam and a hand-held line laser (starting at €19.90). They also have their calibration grids free as printable files. Their wiki has lots of info. I should see if Ebay prices can make it even cheaper for me. I will keep looking for other software and do more research etc. I wonder if any of the file extensions are allowed on commons. We could have a nice database of open source 3D objects that way.--Canoe1967 (talk) 23:42, 3 February 2013 (UTC)
 * You may want to check out a more specialised community for more help. I've seen some discussion of 3D scanners on the RepRap forums. Nil Einne (talk) 06:01, 4 February 2013 (UTC)
 * Thanks again. A local printer does 3D printing. I may pop by and see if they scan and possibly help with financing if they don't. Extrusion of filaments seems over-priced and they may pay me to make an extruder that recycles old plastics, etc.--Canoe1967 (talk) 19:03, 4 February 2013 (UTC)