/kernel_reloaded/ » linux

lm-sensors automatic deployment, issue with sensors-detect

valent — Wed, 16 May 2012 14:39:26 +0000

If you wish to deploy lm-sensors on multiple diferent linux machines issue is with sensors-detect what ask you quite a few questions.

I asked on IRC and got few suggestions. First one is if you wish to accept defaults which sensors-detect suggest you need just to press [ENTER] all the time. To automate this use this one liner:

(while :; do echo ""; done ) | sensors-detect

If you wish to override defaults and answer YES to all questions then use this oneliner:

yes "" | sensors-detect

Maximum wifi speed with OpenWRT? (802.11a Turbo mode aka Super A)

valent — Wed, 09 May 2012 21:23:01 +0000

Hi, we have been testing what is the absolute maximum speed over wifi when using openwrt, for out test we used this hardware:

- 2 x Ubiquity Router station
- 2 x Wistron CM9 802.11a/b/g mini pci cards
- 2 x 3dBi omni antennas

- openwrt version – backfire 10.03.1
- wifi driver – madwifi
- distance – 2 meters (same room)
- encryption – psk2

For benchmarking we installed iperf package and used default settings (tcp packets in one direction).

First we tested “plain” 802.11a mode (hwmode 11a) on channel 40 and we got 30-35Mbit speeds.

Then we switched to 801.11a turbo (hwmode 11ast) and got 55-60 Mbit speeds.

Is this the maximum speed possible? Are there any other tweaks we can do to get faster speeds?

Did you get faster speeds? How? Which gear did you use? We didn’t make results artificially better by using udp packags, my guess by using udp packages we could get near 100 Mbit speeds.

Are there any openwrt tutorials for tweaking and benchmarking maximum speed?

Enable ad-hoc wifi networking on Android

valent — Thu, 12 Apr 2012 15:29:59 +0000

Google has disabled wireless ad-hoc networking in Android from day one. Underlying Android libraries and wifi stack support adhoc networking and so far Google has provided no explanation why it still, even after four years, leaves adhoc disabled.

There has been huge outcry from Android users over this issue, but there is still no answer from Google Android developers.

There are few suggestons on xda-developers forum, and also on Stackoverflow, but most solution so far consisted of using new rom that had ad-hoc support enabled or manually messing about system config files.

But wait, there is an app for that!

There is an app called WiFi Ad Hoc enabler that should work on most Android devices.

If this app works for you, please give it a good review or notify developer of any issues you encounter, but consider that not all Android devices are supported yet.

I would be very grateful if you would vote up my answer on Stackexchange.

[1] https://code.google.com/p/android/issues/detail?id=82
[2] http://forum.xda-developers.com/showthread.php?t=754961
[3] http://stackoverflow.com/questions/1932150/can-android-do-peer-to-peer-ad-hoc-networking
[4] https://play.google.com/store/apps/details?id=nl.arendmedia.wifiadhocenabler
[5] http://www.arenddeboer.com/wifi-ad-hoc-enabler-for-android/
[6] http://stackoverflow.com/a/10108812/1031514

Meteo wifi mesh točke

valent — Tue, 07 Feb 2012 15:09:19 +0000

Krenula je zanimljiva rasprava na CWN (Croatian Wireless Networks) google grupi o Meteo stanicama. Prenosim svoj dio rasprave i pošto vjerujem da će ova tema biti biti zanimljiva i široj geek publici ;)

Ako nekoga zanima i pristup CWN grupi samo se treba javiti i dobije pozivnicu.

>
> @Valent: što to točno radite? nisam upućen

Za prave profi i manje profi vremenske stanice je definitivno najupućenija Istramet ekipa [1] pošto su oni napravili po Istri čitavo čudo meteo stanica i bolje prognoze imaju od DHMZ-a ;) Bili su i na tv-u [2]. Vjerujem da oni najbojle znaju koje stanice valjaju i koje ne, ovisno o kvaliteti i uvjetima u kojima trebaju raditi.

Ono što se radi preko projekta sa ekipom iz Wlan-Slovenije je da se od malih tp-link routera naprave senzorske stanice za sve tipove podataka, pa tako i za meteo podatke [3] ali i za razne druge tipove podataka. Evo kako to može lijepo izgledati [4].

Bila je i super usporedba 5 meteo stanica u emisiji Gadget Show u rangu 1000-2000 kn [5] ali emisiju mozes pogledati online jedino ako imas vpn do engleske ;( ali našao sam i komentare na tu emisiju na nekom forumu [6]

Po meni najbolje uzeti tp-link wr741 i na njega staviti DS18B20+ senzore kao što to radi ekipa iz Wlan-Slovenije [7] i za par sto kuna imaš online meteo stanicu. Mi smo sada naručili 10 senzore i krećemo u
izradu pločice za 1-wire sabirnicu, tako da ćemo uskoro u Osijeku imati 10-ak meteo wifi mesh stanica.

Pozivam i sve ostale da se uključe i u svoja mjesta postave mesh meteo nodove… sada dok je snijeg vani je pravo vrijeme, kada se okopni sve treba biti spremno samo za nakačiti na zidove i krovove ;)

Ako vas zanima više projekt Otvorena mreža možete pročitati članak [8]. Svi novi sudionici na ovome međunarodnome projektu su dobrodošli, ako ste u Slavoniji i Baranji samo se meni javite ili pokrenite ogranak ovog projekta i u svome mjestu ili kvartu ako je veći grad u pitanju. Za sva dodatna pitanja stojim vam na raspolaganju.

[1] http://www.istramet.com/
[2] http://mojtv.hr/video/v/aTfOKdSGduE/istramet-u-dnevniku-nove-tv.aspx
[3] http://dev.wlan-si.net/wiki/Modifications/SimpleThermometer
[4] https://nodes.wlan-si.net/node/kozolectest/
[5] http://fwd.channel5.com/gadget-show/videos/jon-test/jon-test-weather-stations
[6] http://www.hardytropicals.co.uk/forum/viewtopic.php?f=1&t=8456
[7] http://dev.wlan-si.net/wiki/Modifications/SimpleThermometer
[8] http://kernelreloaded.blog385.com/index.php/archives/projekt-otvorena-mreza/

Projekt Otvorena mreža

valent — Mon, 29 Aug 2011 07:22:52 +0000

Projekt Otvorena mreža Osijeka podržava udruga Osijek Wireless, no projekt ne pripada isključivo udruzi niti ga udruga želi zadržati samo za sebe. Ovo je projekt svih građana i tko god želi može se uključiti u njega. Ishod i uspjeh ovog projekta ovisi o cijeloj zajednici.

Jedan je od najvažnijih ciljeva napraviti platformu koja će biti otvorena za razne druge aktivnosti – od pristupa internetu za turiste i građane i omogućavanja besplatnih telefonskih razgovora unutar mreže do postavljanja senzoričkih platformi za mjerenje bilo koje vrste podataka (temperatura, buka, padaline, i dr.), postavljanje web kamera i sl.

Jednako važan cilj ovog projekta jest i edukacija mladih kroz besplatne radionice, a u području novih tehnologija poput rada računalnih žičanih i bežičnih mreža, Linux operativnog sustava, mikroelektronike, programiranja i dr. kroz besplatne edukacije, koje će započeti u rujnu ove godine. Svi koji žele moći će se upoznati s osnovama rada bežičnih mreža i Linux OS-a te kako projekt Otvorena mreža Osijeka radi s tehničke strane.

Ovaj projekt pomaže u premošćivanju digitalnog jaza koji je obično najizraženiji u ruralnim krajevima i područjima pogođenima finacijskom krizom.

Projekt Otvorena mreža međunarodni je projekt u kojem sudjelujemo zajedno s Austrijom i Slovenijom. Osijek je trenutno prvi grad u Hrvatskoj uključen u ovaj projekt, no uskoro će se uključiti mnogi drugi gradovi i općine. Mnogi gradovi imaju nekoliko internet pristupnih točaka, neki čak i cijele mreže, ali nitko tu mrežu nije iskoristio kao platformu za ostale projekte.

Početnu fazu projekta čini postavljanje 100 pristupnih točaka povezanih u cjelovitu mesh mrežu, no to nije cilj projekta, već sredstvo pomoću kojega bi se pravi ciljevi projekta mogli ostvariti.

Da ne bude nesporazuma, s tehničke strane dobro znamo kako će projekt biti napravljen, no tehnički je dio samo jedan mali dio cjelokupnog projekta.

Projekt je otvoren za suradnju s učenicima, studentima, građanima, Gradom, Županijom, CARNetom, Sveučilištem J. J. Strossmayera i njegovim sastavnicama (ne isključivo samo tehničkim fakultetima), ISP tvrtkama, informatičkim i drugim tvrtkama, te svima ostalim organizacijama i ustanovama.

Kako sve ne bi ostalo na razini priče, u sljedećih ćete nekoliko dana moći provjeriti kako je projekt Otvorena mreža osmišljen osobno isprobavajući rad i učinkovitost postavljenih pristupnih točaka.

Jedna je pristupna točka već postavljena i nalazi se u probnom radu oko dva mjeseca. Tijekom tog vremena točka se pokazala 100% stabilnom i pouzdanom, čak i pri spajanju većeg broja korisnika . Točka je privremeno bila postavljena na Srednjoškolskom igralištu tijekom održavanja Pannonian Challeng-a.

U projekt Otvorena mreža Osijeka nije uključena niti jedna politička stranka, županija, grad (bilo u Hrvatskoj bilo izvan nje), niti je projekt financijski podržan s bilo čije strane. Radi se prvenstveno o projektu građana volontera te će takav primarno i ostati, uz otvorena vrata svima koji se žele priključiti projektu ili ga na bilo koji način poduprijeti.

Projekt je organiziran prema meritokratskom načelu gdje osoba koja ima najviše praktičnog znanja iz bilo kojeg područja vodi i snosi odgovornost za taj segment projekta.

Kako nije ograničen isključivo na područje grada Osijeka, u projekt se može uključiti bilo koja privatna ili pravna osoba iz bilo kojeg grada.

Pri izradi projekta i financijskog plana svih troškova izračunali smo kako je za postavljanje 100 pristupnih točaka potrebno izdvojiti oko 250,000,00 kuna. To uključuje cijenu za svu opremu, internet linkove te minimalne financijske naknade za dvije osobe koje bi radile na održavanju mreže.

Također smo izračunali da projekt može biti u potpunosti financijski samoodrživ. Čak i ako bude podržan od strane svakog 10-og građanina Osijeka koji bi donacijom u iznosu od samo 10,00 kuna mjesečno za prve dvije godine i 5,00 kuna mjesečno za naredne godine sudjelovao u projektu, financijska održivost projekta je osigurana.

Volonteri projekta ne očekuju nikakvu financijsku dobit sa svoje strane, no za nabavku opreme, internet linkova i održavanje mreže potrebno je odvojiti određena sredstva, a ista se namjeravaju prikupljati kroz razne oblike donacija i sponzorstva, prijavom na natječaje za udruge, ali i kroz izravne donacije onih koji podržavaju ovaj projekt.

Pratite razvoj projekta Otvorena mreža na Facebook stranici projekta.

OpenWRT installation from Tomato

valent — Thu, 25 Aug 2011 07:14:38 +0000

I have an older Linksys WRT54GL v1.1 with Tomato firmware. Although I’m a hardcore Linux geek I never used OpenWRT, yeah, I know – shame on me ;)

OpenWRT wiki has installation instructions that explain how users should first install 2.4 linux kernel based image, set some nvram options, and then install or update to latest 2.6 based firmware image, but WIKI has no links how to do an update.

Tomato firmware can be accessed via telnet, if you enable telnet service by pressing button for 4 seconds or longer.

So I set nvram options (nvram set boot_wait=on && nvram set boot_time=10 && nvram commit && reboot)

After dowloading latest OpenWRT backfire firmware (brcm-2.4) flashing was straightforward through Tomato Web UI via Update Firmware tab.

Two things confused me. First is that nvram options aren’t explained on the wiki, what they do and why is that step necessary. Second is that there are no download links so for first time OpenWRT user this is quite confusing.

How do I know where 2.4 kernel based images are located and where are 2.6 kernel images located?!? I was not sure if I was flashing the wrong one and maybe bricking my device.

Now even after I used latest backfire 10.03.1-rc5 brcm-2.4 I have 2.4 based kernel image. Where from do I get 2.6 kernel openwrt firmware from? Or I just need to do an update?

First impressions of OpenWRT are awesome.

I also googled for DD-WRT vs OpenWRT comparison but on forums I just found comaparation of different project ideas (cathedral vs bazaar approach) and no feature or other technical comparison.

Fedora in Public Libraries

valent — Mon, 04 Jul 2011 20:27:25 +0000

Our local Linux Users Group in my home town of Osijek has started workshops called knowledge exchange in partnership with our public library. So first step was to install Fusion Linux Fedora Remix on their PCs.

Are there other examples with Fedora being rolled out in public libraries or in some other public institutions? I would be really interested with their experiences.

In my example there are 6 PCs that are used by any member of library, usually those are primary and high school kids. They come here and most of their activities are watching youtube, logging onto facebook and playing flash games.

Their primary OS is Windows XP with Windows SteadyState enabled. I found out that they decided to use Windows SteadyState because they had problem monitoring kids and they would leave p2p apps running and downloading music and video files and come back a day later with hard drives to save them onto. Obviously that is not what they want kids to do so by enabling Windows SteadyState any files downloaded are erased by reboot. This policy probably also removes most virus issues, both because kids don’t plug any usb devices and because any changes are erased.

First issue I came across was that Anaconda installed and GParted wouldn’t resize single windows ntfs partition because there were some errors on hard drive. I tried logging into Administrator account and running chkdsk /f but that didn’t help, even with option that Windows SteadyState merges changes. I didn’t want to disable Windows SteadyState so I reverted to boooting of Windows live CD and running chkdsk /f from repair console. That fixed the issues on all machines.

I didn’t have good experience with Anaconda ntfs resize so I used GParted to resize ntfs partitions. GParted worked perfectly on all machines without issues.

After installing Fusion Linux I did these post install tweaks:
* Change grub entry “Windows XP” from “other”
* Change grub entry to Fusion Linux 14 from Fusion Linux 14.1 (2.6.35.13-92.fc14.i686)
* Put 10 seconds wait in grub menu
* Enable automatic login
* Disble screensave password lock
* Enable automatic updates
* Put Firefox, Chromium and Teeworlds icons on desktop

What would be best way to enable “Windows SteadyState” equivalent in Fedora? Brute force way would be a simple script that deletes all files in user home folder. Are there some more subtle ways? And how to make some changes permanent while making all other changes transient? Using unionfs seams like a bit of a overkill… Any suggestions are welcome.

i-gotU GT200 GPS on Fedora

valent — Sat, 26 Mar 2011 11:30:01 +0000

i-gotU GT200 GPS is the greatest pocket GPS gadget you can find, if you are a geek then this is one gadget you have to get.

Why is it so great? It is a really cheap GPS device (around 55$ or 45€), it has a great SiRF III chipset and it works as a standalone GPS logging device because it has on-board memory! Did I mention it is really cheap? ;)

i-gotU GT200 software that comes with doesn’t have support for Linux or Mac.

The good news is that there is a project called igotu2gpx that adds Linux and Mac support for this great device!

To get this utility running on Fedora here are step by step instructions on how to do it:



su -

yum install bzr ctags gcc-c++ libstdc++-devel boost-devel qt-devel libusb-devel chrpath

exit

bzr branch lp:igotu2gpx

cd igotu2gpx

/usr/lib/qt4/bin/qmake

make

su

make install

ln -s /usr/local/lib/libigotu.so.1 /lib/

exit

You can use GUI tool by running igotugui command or cli version by using igotu2gpx command.

To download gps tracks from your i-gotU GT200 GPS use this command:
igotu2gpx dump -f gpx > track.gpx
And to clear GPS memory just use this command:
igotu2gpx --action clear

You can use igotU GT200 as GPS sensor on your PC or laptop via USB cable but first you need to initialize it:
su - modprobe navman echo -n "0x0df7 0x0900" > /sys/bus/usb-serial/drivers/navman/new_id

Now you can start gpsd and all aplications should see GPS dongle:
gpsd -b -N -D2 /dev/ttyUSB0

If you want to use igotU GT200 via bluetooth you can use this Bluetooth GPS Fedora howto guide to set it up.

Supress cp “Do you want to overwrite” prompt in Fedora

valent — Sat, 05 Feb 2011 20:19:00 +0000

When you try to copy one file over existing one as root user in Fedora you will be asked to confirm that action, but as regular user you can overwrite existing files without any question. So you can easily overwrite your own personal files, GNOME settings, documents, images, etc.

It is obvious that this is policy is made from sysadmin point of view. Sysadmins usually doesn’t care if people mess up or delete their own files, as long as they don’t mess up or damage system in some way.

If you look in .bashrc file of your root account you will find alias for rm, cp and mv commands:

alias rm='rm -i' alias cp='cp -i' alias mv='mv -i'

I would argue that these aliases should be enabled also for regular users to keep them from messing up their files.

If you are a power user and you need to copy over whole directories over existing files you probably don’t want to keep hitting that “y” button over and over.

Only way I found out that you can suppress being asked annoying “overwrite y/n” question is by deleting alias cp='cp -i' definition from root user’s .bashrc file.

But maybe it is better to have protective policy enabled and just temporariliy disable it by using unalias cp command.

If you know other way to disable being asked confirming question for overwriting existing file please explain how in comments.

Compile Blender 2.56 on Fedora 13 and 14

valent — Tue, 25 Jan 2011 15:30:52 +0000

To have Blender 2.56 successfully running on Fedora 13 and Fedora 14 you need to compile it from source.

This is not as hard as most people would think if you follow these simple instructions.

1. Install needed package dependencies
2. Download Blender source
3. Edit scons config file (WITH_BF_FFMPEG = False)
4. Compile Blender
5. Run Blender

So lets start with first step:
UPDATE: There were two dependencies missing: gettext and gettext-devel

 su -

yum install gcc-c++ subversion esound-devel freeglut-devel libjpeg-devel libogg-devel libpng-devel libtool libvorbis-devel freealut-devel openssl-devel python3-devel scons SDL-devel zlib-devel libtiff-devel libXi-devel xorg-x11-proto-devel libGL-devel libGLU-devel freetype-devel OpenEXR-devel glew-devel libsamplerate-devel fftw-devel ftgl-devel ode-devel openjpeg-devel qhull-devel gettext gettext-devel -y exit

Second step is also really easy:

cd ~

mkdir blender-build

cd blender-build

svn co https://svn.blender.org/svnroot/bf-blender/trunk/blender

Edit scons config file
Just open Linux config file, find line with “WITH_BF_FFMPEG = True” and change it to “WITH_BF_FFMPEG = False”:

gedit blender/build_files/scons/config/linux2-config.py

Now compile Blender:

cd blender

python scons/scons.py

Running Blender
After compilation blender binary executable file is located in ~/blender-build/install/linux2/blender. So just create symbolic link to it:

ln -s ~/blender-build/install/linux2/blender ~/blender-build/blender/

When you start Blender you should see something like this in terminal:



$ ./blender

Info: Config directory with "startup.blend" file not found.

found bundled python: /home/liveuser/blender-build/install/linux2/2.56/python