Stefan Helander

Joomla! Component skeleton or framework

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I was going to develop a Joomla! Component for a client and started to read the documentation on how to build a Joomla! Component. I searched online for a skeleton or framework so I didn’t have to program that from scratch. Googeling it didn’t show up any really good results.

Until I realized there are actually services for this. Component Creator is one of them. Through a web interface you can specify the details for your component and you can download a ZIP-file which is installable for Joomla! to start bulding upon.

However, documentation is something not really existing for Component Creator. Instead there are community forums and some video tutorials. I was searching the forums for a specific matter and it turned out that the same question had been asked several times by other users. The reply from the Component Creator staff was that you will get the answer to that question by buying the Premium service. So instead of documenting an answer to a common question they want each client to contact the support team to get the answer, probably in order to sell more Premium subscriptions. A bit odd to me. The free service is so limited anyway so without the Premium subscription you quickly run into it’s limitations, so they will sell them anyway.

You should also be aware that Jensen Technologies who is behind Component Creator also is a consulting business offering development of Joomla! components. So your supplier will also be kind of your competitor. I am not saying they will go and steal your business or clients but it is not always a healthy thing when your supplier is also your competitor. Their in house developers will naturally always have the best support compared to their clients.  If it was me, I would have split it into two different companies.

Anyway, the Component Creator is a powerful and helpful tool when starting a new component project for Joomla!.

The video tutorials can be found here:

There is also a webinar recorded on Youtube here:

Below is a demonstration of building a component in 30 minutes using Component Creator by Søren Beck Jensen (2015).

Stefan Helander

How to keep WordPress widgets when switching themes

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When you switch from one theme to another in WordPress you will discover that all widgets you had is gone. Is there a way to keep the widgets when switching themes?

Short answer is – no. The widgets are set specifically for the theme.

But it is often quite simple to resolve the situation. After you switch theme, go to Appearance -> Widgets and scroll down to the bottom of the page.

Here you will find Inactive widgets. You can simply pull them back into your new theme’s widget position and get them back where you want them.

WordPress widgets

WordPress widgets

However, if the widgets you were using was part of the theme you switched from, they will not be available when using the new theme so in that case you need to find an alternative plugin or widget.

Stefan Helander

Meltdown and Spectre vulnerabilities – what to do?

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Meltdown and Spectre are two vulnerabilities present in hardware making it potentially possible for programs to steal information, like passwords etc.

Meltdown affects only Intel processors while Spectre, which is more complex, also partly affects AMD and ARM based processors.

It is not yet known if these vulnerabilities has been exploited by anone. It can affect personal computers, servers, tablets and mobile phones, i.e. more or less any device containing a processor.

More information on: https://spectreattack.com/

What can you do?

  • Check your operating system for updates the upcoming weeks (this is normal good security practice, but make sure you do it frequently)
  • Install and update your virus protection. Even if the antivirus program can’t protect you from the attack it might be able to inform you that your device has got malicious code onboard

You can find security bulletins, security advisorys, faq:s etc for your operating system here: https://meltdownattack.com/#faq-advisory

Stefan Helander

Asterisk no sound from client

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I was running an Asterisk server behind NAT without any problems at one location. Due to reoargnization it was moved to a new location and placed behind a pfsense firewall. After a while users reported increasing problems with no sound from the clients.

It turned out running a SIP server behind a pfsense can be problematic. When moving to the SIP server to a white IP-adress (no NAT), protecting it using iptables firewall on the SIP-server, all problems disappeared.

It should be noted that the pfsense firewall was not running the latest version of pfsense so it could be caused by a problem solved in later versions of pfsense. However, for different reasons it was not possible to upgrade pfsense so the solution was to move the SIP-server from behind pfsense.

Stefan Helander

How to vertically center text in a div

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This is a neat way of centering text in a div. Live demo here.

 

<html>
<head>
 <title>Vertical text center demo</title>
</head>
<body>
<style>
.textbox {
 height: 200px;
 width: 300px;
 text-align: center;
 font-size: 14px;
 font-weight: bold;
 background-color: blue;
}
.textbox p {
 height: 100%;
 display: flex; /* vertically center text */
 justify-content: center;
 align-content: center;
 flex-direction: column;
 margin: 0 50px;
 color: white;
}
</style>
<h1>Vertical text center demo</h1>
<div class="textbox">
 <p>This text is vertically centered in the box</p>
</div>
</body>
</html>
Stefan Helander

Unable to mount NTFS filesystem due to hibernation

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I had retrieved a harddisk out of a broken laptop containing Windows 10 in order to retrieve some files from it. The harddisk had been removed from the broken laptop and then installed in a HDD enclosure with USB connection. When I connected it to a Windows computer I could browse the Users folder but clicking on a user’s folder displayed a message that I didn’t have permissions to open it unless I continued as administrator. After the progress bar had went to 100%, I still couldn’t access the folder.

Instead I connected it to a Linux/Ubuntu computer and now the message “The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the `ro` mount option.” was displayed when connected. The original laptop had been in a hibernate state when it broke which locks the filesystem.

It turned out that the easiest solution was to connect the USB harddrive to a laptop and press F10 to select boot device during boot up (the key might be different depending on brand, on my Samsing it was F10). I selected the USB harddisk and it booted after fixing the disk automatically. I was actually a bit hesitant to do this because I know from earlier Windows version that it usually was a hopeless task to boot on a harddisk that had been moved from one host computer to another. In Windows 10 it looks like they have fixed this.

I could log in to Windows as the original user and retrieve the files. After shutting it down in a controlled manner, it was also possible to mount the disk in Linux/Ubuntu..

Stefan Helander

Ispconfig3 unable to store client on DNS and email domain records

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After upgrading from Ispconfig 3.0 to 3.1 odd things started to happen. For example, when saving a DNS secondary zone it would not store the client selected. Same thing when saving an email domian, client info and spam filter setting just would save.

The solution turned out to be simple. Gentlemen – clear your cookies and login again! Problem solved.

Stefan Helander

High load on CPU and disk I/O every hour (Apache, MySQL and mod_pagespeed on Ubuntu)

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On one of my Ubuntu servers I noticed a significant peak in CPU load (load average, LA) and disk I/O about every hour. At first, I suspected that MySQL was the cause of this, doing some houeskeeping or garbage cleaning.

However, it turned out it was caused by the Apache module mod_pagespeed. The high load occuered when pagespeed was cleaning out it’s cache.

The solution was to locate the cache on tmpfs instead. This was done by editing the file /etc/apache2/mods-available/pagespeed.conf and change the location of the cache by the line (/run is located on tmpfs which is RAM memory):

ModPagespeedFileCachePath "/run/cache/mod_pagespeed/"

Then restart Apache by:

service apache2 restart
Stefan Helander

HP Procurve MSM422 / MAP-625 clients flow the dhcp server [solved]

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A client was using the HP Procurve MSM422 / MAP-625 MultiService Access Point (wifi). It was being used in a rather crowded wifi environment and the problem was the wifi clients keept reconnecting and renegotioating so often that the DHCP server was overflowed, sometimes with DHCP requests every few seconds. They had been struggling with the problem for a couple of months and the focus was aimed at the DHCP requests.

It turned out that the problem was not in the DHCP negotiation at all, but was caused by the wireless clients that keept losing connection and each time when they reconnected a DHCP request was sent.

The client was misinformed, that 5 GHz band was prohibited in the country where it was set up (which is acutally not). So both radios (radio 1 and 2) where set to 2,4 GHz where radio 1 was set to 802.11n/b/g and radio 2 with 802.11b/g.

Furthermore, for radio 2 the value of the Antenna gain was set to the maximum which is 29 dBi in an attempt to boost the maximum power out of the system. However, this field works the opposite. In order to be regulatory compliant and not emit more than the allowed power, this field informs the system that it is connected to an antenna with 29 dBi gain, so to not emit illegal levels of power (output power + antenna gain), the system will reduce the actual output power (i.e. the power input to the antenna) by 29 dBi. But the system was using the internal antennas which, I guess, has more or less no antenna gain. This caused the system to actually emit -29 dBi, i.e. a very weak wifi signal.

The low power output made it hard for the wifi clients to “hear” the access point, which caused them constantly to lose connection and when reconnecting, they were sending a DHCP request, hogging down the DHCP server.

Solution:

  • Radio 1 was configured to use the 5 GHz band. This band is much less crowded than the 2,4 GHz band and the bandwidth is better, so when a client has the possibility, it is preferred if it can use the 5 GHz band.
  • Radio 2 was configured to use Internal Antenna with 0 dBi antenna gain.

Settings used when the problem was solved like this (click on the image to enhance it):

HP Procurve MSM422 MAP-625

HP Procurve MSM422 MAP-625

Stefan Helander

“Not a valid image” when trying to upload images in Joomla! 3.7

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Error message “Not a valid image” displayed when trying to upload an image in Joomla! 3.7. The error message is displayed even though the file type being uploded (jpg or png for example) is existing as valid type in both valid file types and mime types fields.

Solution: Go to System -> Global configuration -> Media and select Check MIME types = No