Repeater beállítása

Cél: jelenlegi vezeték nélküli hálózat hatósugarának kiterjesztése egy REPEATER eszközzel.
Példa a felépítésre:

ÚTVÁLASZTÓ (ROUTER) - Internetre kapcsolódó eszköz
STATIKUS CÍM
IP cím pl.: 192.168.1.100
DHCP BE
|
| WLAN ---)))
|
WiFi elosztó - REPEATER
STATIKUS CÍM - DHCP és tűzfal KIKAPCSOLVA

IP cím pl.: 192.168.1.101

GW+DNS is ROUTER IP (192.168.1.100)
|
| WLAN ---)))
|
PC/egyéb kliens
STATIKUS CÍM
IP cím pl.: 192.168.1.1
GW+DNS is ROUTER IP (192.168.1.100)
stb.

FONTOS!
Ugyanazon az alhálózaton kell lenni az eszközöknek, hogy kommunikálni tudjanak!
http://en.wikipedia.org/wiki/Subnetwork

"As it looks Johnny your two devices are on different Subnets, thats why they can't communicate!
You will need to change the IP of the Linksys to 192.168.0.2 for them to be able to communicate. You will also need to disable the DHCP (if it is turned on) on the Linksys.
You can find both of these settings on the Linksys configuration under LAN Settings.
Also if there is a firewall running on the Linksys turning it off will make things easier for you. The D-Link will handle the firewalling for your network!
Turn off the D-Link and set up the Linksys as I described above. When finished the setup save you settings and turn the D-Link back on and you should be fine!
Cheers!"
http://www.tomshardware.co.uk/forum/40841-43-wireless-repeater-headache

CODE_n

Kellene egy kis hátszél a Nagy Ötlethez?

"The CODE_n initiative offers an ecosystem designed to network digital pioneers and support the development of new, digital business models."

https://www.code-n.org

ActiveMQ on Ubuntu 14.04 x64 VPS - Solve OutOfMemoryError, Could not reserve enough space for object heap

You need some tweaks to run ActiveMQ in a resource-constrained VPS environment, I've tried this on a VPS that had 2GB RAM.

0. Download ActiveMQ, extract to /opt/activemq and run:

./activemq setup



1. Tweak JAVA minimum heap memory and max heap size - run and also put this line to ~/.bashrc :

export JAVA_OPTS="-Xms128m -Xmx512m"


Verify settings:

echo $JAVA_OPTS
-Xms128m -Xmx512m

echo $_JAVA_OPTIONS

(empty)



2. Limit resource usage (memoryUsage -> 32MB):
nano conf/activemq.xml

          <systemUsage>
            <systemUsage>
                <memoryUsage>
                    <memoryUsage limit="32 mb"/>
                </memoryUsage>
                <storeUsage>
                    <storeUsage limit="10 gb"/>
                </storeUsage>
                <tempUsage>
                    <tempUsage limit="10 gb"/>
                </tempUsage>
            </systemUsage>
        </systemUsage>



3. Comment out a few transport Connectors


        <transportConnectors>
            <!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
            <transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>

      <!--      <transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
      
-->
  </transportConnectors>




4. Set ACTIVEMQ_OPTS_MEMORY and ACTIVEMQ_OPTS

nano /etc/default/activemq

# Set jvm memory configuration
if [ -z "$ACTIVEMQ_OPTS_MEMORY" ] ; then
ACTIVEMQ_OPTS_MEMORY="-Xms128M -Xmx512M"
fi

# Uncomment to enable audit logging
#ACTIVEMQ_OPTS="$ACTIVEMQ_OPTS -Dorg.apache.activemq.audit=true"
ACTIVEMQ_OPTS="$ACTIVEMQ_OPTS -Dorg.apache.activemq.UseDedicatedTaskRunner=false"



5. Setting up proper passwords:

/opt/activemq/conf# nano jetty-realm.properties

# username: password [,rolename ...]



Error messages on a VPS with 2GB RAM before tweaks:

INFO: Loading '/etc/default/activemq'
INFO: Using java '/usr/bin/java'
Error occurred during initialization of VM
Could not reserve enough space for object heap
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.


opt/activemq/bin/activemq console
INFO: Loading '/etc/default/activemq'
INFO: Using java '/usr/bin/java'
INFO: Starting in foreground, this is just for debugging purposes (stop process by pressing CTRL+C)
Error occurred during initialization of VM
java.lang.OutOfMemoryError: unable to create new native thread
at java.lang.Thread.start0(Native Method)
at java.lang.Thread.start(Thread.java:714)
at java.lang.ref.Finalizer.<clinit>(Finalizer.java:226)

./activemq: 453: ./activemq: Cannot fork

ERROR: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.apache.activemq.xbean.XBeanBrokerService#0' defined in class path resource [activemq.xml]: Invocation of init method failed; nested exception is java.lang.OutOfMemoryError: unable to create new native thread
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.apache.activemq.xbean.XBeanBrokerService#0' defined in class path resource [activemq.xml]: Invocation of init method failed; nested exception is java.lang.OutOfMemoryError: unable to create new native thread

Environment details:

ulimit -a

core file size          (blocks, -c) unlimited

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 127259

max locked memory       (kbytes, -l) 64

max memory size         (kbytes, -m) unlimited

open files                      (-n) 1024

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) 10240

cpu time               (seconds, -t) unlimited

max user processes              (-u) 127259

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited

See also:

http://activemq.apache.org/javalangoutofmemory.html

Kiegészítő LaTeX csomagok használata a Gummi, illetve TeX Live szerkesztőkben (Ubuntu 14.04)

Gummi TeX szerkesztő telepítése:

sudo apt-get install gummi 

Futassuk az alábbi két parancsot a Terminálból:

cd ~/.config/gummi
ln -s /usr/share/texmf-texlive

EN: Use additional LaTeX / TeX packages for Gummi or TeX Live on Ubuntu

1. Figure out where you installed the extra packages, from TeX Live or whatever else.  (For me, they live at /usr/share/texmf-texlive/.)
2. Create a symbolic link within the Gummi configuration folder to the TeXLive files:
   • cd ~/.config/gummi
     ln -s /usr/share/texmf-texlive
   Experimentation suggests that pointing Gummi at the top-level directory is sufficient for access to all of the subfolders.  If it fits the structure of your machine better, you could also copy or move the files — but I’d stick with a symbolic link unless you have a good plan in mind.

http://www.pamelatoman.net/blog/2013/11/using-additional-packages-with-gummi/

GRUB és indítóképernyő testreszabás

EN: Customize GRUB wallpaper and boot splash logo - Ubuntu 14.04

GRUB háttérkép beállítása:

Válasszunk ki egy nem-indexelt, RGB típusú PNG képet 640x480-as felbontásban (wallpaper.png)

sudo cp wallpaper.png /boot/grub/
sudo update-grub

Indítóképernyő:

Töltsd le és csomagold ki a ZIP fájlt:
http://data.hu/get/8188574/ubuntu-boot-myimage.zip

sudo cp -r ubuntu-boot-myimage '/lib/plymouth/themes'
sudo mv '/lib/plymouth/themes/default.plymouth' '/lib/plymouth/themes/default.plymouth.backup'
sudo ln -s '/lib/plymouth/themes/ubuntu-boot-myimage/ubuntu-faded-screen.plymouth' '/lib/plymouth/themes/default.plymouth'
sudo update-initramfs -u

Bejelentkezési probléma sudo startx futtatása után

EN: After running sudo startx, system does not log in on Ubuntu Linux.

Problem: user root became owner of ~/.Xauthority file

Solution:
Press CTRL+ALT+F1, log in and run:
sudo chown USERNAME .Xauthority
sudo chgrp USERNAME .Xauthority

Where USERNAME is your user (login) name.

PDF dokumentumokból szöveg készítése (OCR) Linuxon

EN: How to OCR any PDF file on Ubuntu Linux with pdftoppm, convert and tesseract

#!/bin/sh
mkdir tmp 2>/dev/null
cp $@ tmp
cd tmp
clear
echo
echo "Processing $@..."
pdftoppm *.pdf -f 1 -l 100 -r 600 ocrbook 2>error.txt

for i in *.ppm; do
echo "CONVERT: $i"
convert "$i" "`basename "$i" .ppm`.tif"; done

for i in *.tif; do
echo "OCR: $i"
# -l hun  -->> OCR for HUNGARIAN LANGUAGE
tesseract 1>/dev/null 2>error.txt "$i" "`basename "$i" .tif`" -l hun; done
for i in *.txt; do cat $i >> pdf-ocr-output.txt; echo "\n[$1]\n" >> pdf-ocr-output.txt; done
mv pdf-ocr-output.txt ..

# Cleanup
mkdir text 2>/dev/null
mv *.txt text 2>/dev/null
rm * 2>/dev/null
cd ..
#rmdir tmp


Original source (script was modified):
http://ubuntuforums.org/showthread.php?t=880471