Category Archives: Linux
Slow DNS lookup on CentOS 6 machines
Slow DNS lookups can have many reasons. Mostly they are easy to fix because it simply is a wrong IP address of the DNS f.ex. But today i had a harder one, but was easy to fix if you know how… Looking up an address with dig works all the time, but when puppet gets its plugins or other files … Continue reading
Simple Rsync Backup Script
Over the last 10 years i’ve tested and used many different backup solutions for my Linux and Mac machines. I think the very first one i have used regularly was unison. A great tool for bidirectional syncing, but it always had problems with special characters. And, there are many commercial ones out there. The good ones often cost US$ 40-80. Simply too … Continue reading
Log mails sent by PHP mail() function
PHP 5.3 introduced a new feature many administrators have waited for. Now it’s possible to log mails sent by the mail() function of PHP. Until 5.3 it was not that easy to find an insecure form/script which sends out spam messages. But now, finally, after around two years after the patch was submitted, you can add this to your php.ini: The first … Continue reading
Find out the website causing high load on a Apache webserver
If you’re running an Apache webserver with many customer websites, there will be a time (sooner or later) where your server is flooded with a lot of page requests, causing a high CPU-load and memory usage. Specially if PHP or other scripting is used behind. Most of the time this is caused by a harmful script somewhere in the net. … Continue reading
Update kernel and modules of a Raspberry Pi
Last week, i received my new Raspberry Pi with 512MB RAM, which should replace my current 256MB RPi. Unfortunately, i was not able to boot the system with the SD card from the old Pi. The old one was running on kernel 3.2.16-rpi1+, which is a bit older. Because of that, i decided to update the kernel and boot stuff to … Continue reading