Entries by Stefan Helander

Joomla! Component skeleton or framework

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 […]

How to keep WordPress widgets when switching themes

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 […]

Meltdown and Spectre vulnerabilities – what to do?

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 […]

Asterisk no sound from client

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 […]

How to vertically center text in a div

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; […]

Unable to mount NTFS filesystem due to hibernation

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 […]

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

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 […]

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

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 […]

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

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 […]