Stefan Helander

Multiple attributes / combinations in PrestaShop

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Here is the documentation on how to add attributes / combinations to a product in PrestaShop -> http://doc.prestashop.com/display/PS16/Managing+Product+Attributes

If you plan on using multiple attributes for a product, like size and colour, do use the combinations generator and select both the possible sizes and colours at the same time. If you add them by hand one by one you risk ending up with a scenario where only the first attribute is visible in the shopping cart and on the resulting order (like the size but not the colour), i.e. you will have to contact the customer to ask about the other attribute(s).

By using the generator PretaShop will create the all the necessary combinations for you, i.e. size 1 + colour 1, size 2 + colour 1, size 1 + colour 2, size 2+ colour 2 and so on.

 

Stefan Helander

Improving wifi in a crowded wifi environment

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This is a litle trick I use when I travel and hook up to a wifi network in a crowded wifi environment. Sometimes the network performance over wifi is really bad and the problem is that it can be caused by heavy traffic (like file sharing) on another wifi network sharing the same channel as yours. I have experienced this especially when travelling to big cities like Paris, Amsterdam and so on. First of all, it is recommended that you disable 802.11n wifi mode which works terribly bad in crowded environments. See this article for Windows and this for Linux (Ubuntu).

 

Crowded wifi environment (Wifi Analyzer for Android)

Crowded wifi environment (Wifi Analyzer for Android)

The problem with the wifi technology is that networks in the neighbourhood is sharing the same channels. In the 2,4 GHz band there are only 11-14 channels availible (depending on your region) and those channels overlap. That means if your network is on channel 1 you will get interference with traffic on channels 1, 2 and 3. Another problem with wifi is that is has no means of evenly dividing the capacity (like timeslots), so it is kind “the one shouting highest gets the most bandwidth”. And when someone already is using a lot of bandwidth (like file sharing) it is very hard for other users to obtain a part of the bandwidth. Even if it is the neighbours wifi which you can’t access but it shares the wifi channel.

A countermeasure to improve the situation is to constantly use some bandwidth forcing the heavy users to pull back a bit. Before transmitting, each node in the network listens in the air if the channel is free, so by using a little bit of bandwidth even if idle you don’t give the other node the same possibilty to hog the entire capacity.

First of all, find out the IP address of your local network default gateway. In WIndows you run a command prompt (cmd) and type the command ipconfig. In Linux you can use netstat -rn.

To constantly use up a small portion of the bandwidth I use the ping comand. Ping normally sends very small packets (56 bytes), but to get this to work we need a bit larger packets (but not to large, then we will hog the entire capacity). 1024 bytes is good.

In Windows you run the command (replace 192.168.0.1 with the IP-address of your local network which you found out above):

ping -t -l 1024 192.168.0.1

and in Linux you run:

ping -s 1024 192.168.0.1

 

ping with 1024 bytes

ping with 1024 bytes

Voila! Now my wifi connection gets a lot more stable because I force the other wifi nodes to pull pack a bit since I constantly make them aware of my presence.

 

Stefan Helander

Install Ubuntu 14.04 on Samsung Ultrabook Ativ Book 9

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To install Ubuntu 14.04 on a Samung Ultrabook Ativ Book 9, this is how to do it.

I decided to keep the factory installed Windows 8.1 beside my Ubuntu install using dual boot. Thanks to enrish for the basic info. I found out there is no need to shrink the Windows 8.1 partition as long there is space enough for Ubuntu. The Ubuntu installation will do this for you. Before you do anything – make sure you have a backup as usual. If you decide not to keep the Windows 8.1 install, do keep the recovery partitions. No need to install any screen drivers, Ubuntu worked out of the box.

  1. In WIndows, run the Samsung Update Utility and update everything including BIOS/firmware.
  2. In Window Control Panel go to Power options and click on Choose what the power button does. Click on Change settings that are currently unavailable then scroll down and deselect Turn on fast startup (source http://askubuntu.com/questions/221835/installing-ubuntu-on-a-pre-installed-windows-8-64-bit-system-uefi-supported). Restart your system.
  3. When booting, press F2 to enter the setup.
  4. In the Boot section, disable Fastboot
  5. Insert the USB flash drive with Ubuntu ISO (prepared with create startup disk on another computer). 
  6. Configure boot device order, setting the flash drive to be the first option.
  7. Save and reboot. Now the system should be booting on the flash drive.
  8. Select to Install Ubuntu. During installation Ubuntu will recognize that you have Windows 8.1 installed and you have the option to install Ubuntu beside the Windows 8.1. The Ubuntu install will shrink the Windows 8.1 partition to make room for Ubuntu. By dragging the vertical bar you can decide how large the partitions for Windows vs Ubuntu should be. Continue installing Ubuntu as usual.
  9. After installing Ubuntu, unplug the flashdrive and when booting, press F2 and enable Fastboot again.

 

Stefan Helander

Disable 802.11n on Compaq 6910p with iwl4965 in Ubuntu

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I’ve found out that the 802.11n high speed wifi / wlan mode (300 Mbps theoretically) tends to cause more harm than good, i.e. the performance in many, especially crowded, wifi environments will be really poor and it is a better option to turn it off.

My Compaq 6910p laptop comes with an Intel Wireless WiFi Link 4965AGN chipset. The 802.11n mode can be disabled making it fall back to only use 802.11a/b/g modes casuing the connection to be much more stable and often the overall bandwidth will be better.

To check if your chipset is running with 802.11n enabled, enter the command:

sudo iwconfig wlan0

The output will look something like this:

wlan0     IEEE 802.11abgn  ESSID:"XXXXXX"
          Mode:Managed  Frequency:2.462 GHz  Access Point: 00:0C:F6:82:90:28
          Bit Rate=14.4 Mb/s   Tx-Power=15 dBm
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=51/70  Signal level=-59 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:66  Invalid misc:36   Missed beacon:0

If the first line says 802.11abgn your chipset has 802.11n activated.

To disable 802.11n mode do the following:

sudo modprobe -r iwl4965
sudo modprobe iwl4965 11n_disable=1

This will disable 802.11n until next reboot. Now check again with sudo iwconfig wlan0 and the output should display the first line without the “n” after 802.11, like this:

wlan0     IEEE 802.11abg  ESSID:”XXXXXX”
          Mode:Managed  Frequency:2.462 GHz  Access Point: 00:0C:F6:82:90:28
          Bit Rate=54 Mb/s   Tx-Power=15 dBm
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=46/70  Signal level=-64 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:7  Invalid misc:485   Missed beacon:0

If you want to make this change permanent, i.e. always disable 802.11n, do the following:

sudo echo "options iwl4965 11n_disable=1" >> /etc/modprobe.d/iwl4965.conf

After rebooting, verify using sudo iwconfig wlan0 that 802.11n is not enabled.

 

Stefan Helander

Samsung Ultrabook series 5 loses wifi connection intermittently

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On a rather new Samsung Ultrabook series 5 we had intermittent / sporadic connection problems on some wifi networks. The status for the network shifts forth and back between ok and “No internet access”. This doesn’t happen on all wifi networks. It seems the problem is the 802.11n mode, especially in a crowded wifi environment.

The solution (or workaround) is to disable the 802.11n mode in the wifi driver for the Intel(R) Centrino(R) Advanced-N 6235 chipset. This gives a lower bandwidth connection but on the other hand, a stable connection.

  1. Go to the Control panel
  2. Open Network connections (search for it if you have troble to find it)
  3. Right click on your wifi connection and select Properties
  4. Click Configure in the upper part of the box (my screenshot is danish, so it is the button labeled “Konfigurer…”)

    Intel Centrino Advanced N-6235

    Intel Centrino Advanced N-6235

  5. Click on the Advanced tab
  6. Find the 802.11n mode status configuration parameter and select to set it inactive (off)
  7. Click Save / OK in the bottom

 

 

Stefan Helander

VirtueMart not displaying in Components menu after install [solved]

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After installing VirtueMart on a Joomla 2.5 site, it should occur in the Components menu in the Joomla! backend. In my case, it didn’t show up.

The problem can be caused by the Xmap – Virtuemart plugin not being enabled.

Solution: 

Go to the Extensions menu and then select Plug-in Manager.
In the filter box, type "xmap" and press enter.
In the list displaying, check if the Xmap – Virtuemart plugin is disabled (status icon is red).
Then click the status icon for Xmap – Virtuemart so it turns green. Now VirtueMart should be availible in the Components menu.

 

Enabled VirtueMart Xmap plugin
Stefan Helander

Fix the Heartbleed Bug on Ubuntu

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OpenSSL on Ubuntu can be vulnerable to the Heartbleed Bug. Not all versions of OpenSSL are affected though. 

OpenSSL version 1.0.1 to 1.0.1f are vulnerable.
OpenSSL version 1.0.1g are not vulnerable.
OpenSSL branches 1.0.0 and 0.9.8 are not vulnerable.

To fix this issue on Ubuntu systems: 

Check your OpenSSL version to see if it is vulnerable to the bug:

openssl version

If it says 1.0.1 check the build date:

openssl version -b

If it says anything before Apr 7 2014 you need to update OpenSSL. Proceed as follows:

sudo apt-get update
sudo apt-get install openssl
sudo apt-get install libssl1.0.0

Now verify that you are running the updated OpenSSL libraries:

openssl version
openssl version -b

The build date should now come out Apr 7 2014 or later.

Now you need to regenerate your SSL certificates as they might been compromised. A guide can be found here: https://www.digitalocean.com/community/articles/how-to-create-a-ssl-certificate-on-apache-for-ubuntu-12-04
 

 

Stefan Helander

Windows Live Mail (WLM) problem setting IMAP Sent mail folder

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When configuring Microsoft Windows Live Mail (WLM) with an IMAP email account, you should set which folders on the IMAP server that should be used for Sent, Drafts, Deleted and Junk email. This is done by going into the setup for your email account in Windows Live Mail, edit properties for the account and select the IMAP tab. Your email server provider should be able to inform you about the correct IMAP folder names. Normally the root prefix folder should be Inbox. 

However, in some cases (versions) of WLM there seems to be a bug so when setting the root folder to Inbox your Inbox will not be visible in the left pane. A workaround (solution) is to leave the root folder empty and instead prefix your IMAP folder names with "Inbox." like Inbox.Sent for the sent folder. Like this (sorry for the swedish version screenshot, didn’t have an english WLM at hand): 

Windows Live Mail IMAP folders

Windows Live Mail folders for Sent, Drafts, Deleted and Junk mail

Stefan Helander

Joomla multi language problem when trying to change menu item from ‘All’ to a specific language

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When setting up a Joomla site for multilanguage you need to set a default menu item for each language. However, sometimes it is not possible to change a default menu item currently set to language "All". The error message displayed is: 

"Warning Save failed with the following error: The Language parameter for this menu item must be set to 'All'. At least one Default menu item must have Language set to All, even if the site is multilingual."

A solution is to do the following:

  1. Select the menu item by checking the checkbox for it to the left in the menu items list.
  2. Then scroll down to the batch change item (found under the list of menu items).  
  3. In the drop down list "Select language" you select the language you wish to set the menu item to.
  4. In the drop down list "Select Menu or parent for Move/Copy", select the menu where item currently is located in.
  5. Select the Move radio button
  6. Click Proceed.

Problem solved!

 

Stefan Helander

[Solved] Samsung Galaxy Note II (GT-7105) + Plantronics Voyager Legend bluetooth headset poor audio quality

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I recently bought a Plantronics Voyager Legend headset to use with my Samsung Galaxy Note II phone. It worked fine for a day or two, then I started to experience poor sound quality. Especially the person I was talking to had real trouble hearing me. Restarting bluetooth in the Samsung or restarting the Plantronics headset did not help. But restarting the Samsung Galaxy Note II resolved the problem momentarily – after a day or two the problem returned.

Before returning the headset to the dealer I decided to have a look at Plantronics website and found out there are a firmware update procedure availible on their website. To get the update software running on my Windows 8 PC I had to run the installer as administrator. When returning to the update window in the browser (yes, the update procedure is done all in the browser), I found my headset was running firmware version 44 and an update would update it to version 93.

After updating the firmware all quality issues where gone. 

To update the Plantronics headset visit http://www.plantronics.com/us/support/myheadset/updater/