Linux

When we moved into our new house five years ago, the electrical installation came with a full KNX bus: lights, blinds, heating actuators, the garage door, a weather station, all wired up and configured through ETS by the electrician. On top of that we had a handful of separate smart-home ecosystems that had nothing to do with KNX: a Reolink camera setup, a Zehnder ComfoAirQ ventilation system, a Kostal Plenticore inverter for the PV system, some Woox smart plugs, and a couple of Wi-Fi devices sitting in the Smart Life / Tuya app. KNX itself was visualized through the manufacturer’s native app, AmbiHome.

I scan all my incoming mail into Paperless-ngx. Nothing fancy, just regular letters and correspondence, duplex, 300 dpi, color. The volume isn’t huge, but it annoyed me every single time: a duplex page took 45 seconds to go through the ADF of my Epson WorkForce Pro WF-C5890. That’s a long time to stare at a scanner for a single sheet of paper, and it was bugging me enough to actually chase it down.

Some weeks ago I decided to move my notes from Microsoft OneNote to Joplin. Microsoft OneNote is a great tool for taking notes collaborative, but sometimes it drives me insane and I wanted a more portable form at for my notes.

Markdown is a perfect portable format, and it is widly adopted. I really like the idea behind Markdown, and I even supported a Microsoft User Voice to add native Markdown support into OneNote. So my new note taking tool had to support Markdown. Long story short: Joplin was my tool of choice. It’s running on Windows and there is also an iOS app. Joplin offers a wide range of options to sync the notes, but none of them seemed to fit my use case - Except for the Joplin Server. I’m not afaraid in running my own infrastructure. I have some Azure credits available each months, so running a small VM for a Joplin Server is a good way to use them.

I have wrote about the installation of PowerShell Core in Linux Mint 18 yesterday. Today, I want to show you, how to install Visual Studio Code on Linux Mint 18. The installation is really easy:

1. Download the deb package
2. Install the deb package
3. Run Visual Studio Code

You can download the latest packages for Windows, Linux (deb and rpm, if you want even a tar ball), and Mac on the Visual Studio Code download page. Download the deb file. To install the package, open a Terminal window and run dpkg .

Beside my Lenovo X250, which is my primary working machine, I’m using a HP ProBook 6450b. This was my primary working machine from 2010 until 2013. With a 128 GB SSD, 8 GB RAM and the Intel i5 M 450 CPU, it is still a pretty usable machine. I used it mainly during projects, when I needed a second laptop (or the PC Express card with the serial port…). It was running Windows 10, until I decided to try Linux MInt. I used Linux as my primary desktop OS more than a decade ago. It was quite productive, but especially with laptops, there were many things that does not worked out of the box.

While searching for a simple monitoring für my root servers, I’m stumbled over a python-based software called Simplemonitor. Other alternatives, like Nagios, or forks like Incinga etc., were a bit too much for my needs.

What is SimpleMonitor?

SimpleMonitor is a Python script which monitors hosts and network connectivity. It is designed to be quick and easy to set up and lacks complex features that can make things like Nagios, OpenNMS and Zenoss overkill for a small business or home network. Remote monitor instances can send their results back to a central location.

I don’t like to use untrusted networks. When I have to use such a network, e.g. an open WiFi network, I use a TLS encrypted tunnel connection to encrypt all web traffic that travels through the untrusted network. I’m using a simple stunnel/ Squid setup for this. My setup consists of three components:

• Stunnel (server mode)
• Squid proxy
• Stunnel (client mode)

What is stunnel?

Stunnel is an OSS project that uses OpenSSL to encrypt traffic. The website describes Stunnel as follows:

The downside of using WordPress is that many people use it. That makes WordPress a perfect target for attacks. I have some trouble with attacks, and one of the consequences is, that my web server crashes under load. The easiest way to solve this issue would be to ban those IP addresses. I use Fail2ban to protect some other services. So the idea of using Fail2ban to ban IP addresses, that are used for attacks, was obvious.

As a frequent reader of my blog, you might have noticed that vcloudnine.de was unavailable from time to time. Reason for this was, that my server was running out of memory at night.

Jan  1 05:22:16 webserver kernel: : httpd invoked oom-killer: gfp_mask=0x200da, order=0, oom_adj=0, oom_score_adj=0

Running out of memory is bad for system uptime. Sometimes you have to sacrifice someone to help others.

It is the job of the linux ‘oom killer’ to sacrifice one or more processes in order to free up memory for the system when all else fails.

By default, CentOS 6 comes with Python 2.6. This is a bit outdated, especially if you take into account, that Python 2.7.11, which is the latest Python 2 release, was released in December 2015. If you are new to Pyhton, you will usually start with Python 3. Currently, Python 3.5.1 is the latest Python 3 release. So, Python 2.6 is REALLY old.

Okay, I could use another distro. Ehm… no. CentOS is the is the open-source version of Red Hat Enterprise Linux (RHEL). It was, and it is, designed to be similar to RHEL. CentOS runs only the most stable versions of packaged software. This greatly reduces the risk of crashes and errors. The downside is… Python 2.6. Or Apache 2.2. Or MySQL 5.1. Switching to CentOS 7 is difficult, because there is no inplace upgrade.