Banana Pi Case Remod

25. Februar 2015 in GNU/Linux, Physik, Technik.

I cut a bay for my Clicktronic HDMI-to-DVI adapter into my Banana Pi case.

Photo of the new connector configuration

HDMI adapter bay milled into the case (lower half with board, power and display connectors attached).

To maintain structural stability of the case, I had to cut about one half of the bay into the lower half of the case and the other into its upper half. To do this, I had to raise the mount level of the board by about 5 milimeters (to some 15 milimeters above case interior bottom overall).

Luckily, the front and back panels do have generous enough openings for the other connectors (Ethernet, dual USB host ports, SD card) to still pass through.

Also, the (massive) HDMI connector/adapter thing is savely hinged into the cut of the bay, which fits it tightly, hindering the adapter from excessive tilting, which could lever the board out of it’s socketing or (worse) tear the HDMI connector from the board.

But the fix-mounted USB power supply now hung „in the open“, passing any stress on it directly over to the connector and board.

Lesen Sie mehr »

RDP With Copy&Paste From Windows to xrdp on Debian

11. Juli 2015 in Administration, GNU/Linux.

The package of xrdp (Version 6.1.2) that is available in Debian does lack support for Copy&Paste.

The „master“ branch of xrdp on github provides this feature but is not packaged for Debian at the moment.

To have it available, I built it manually on my Debian server. The procedure took about 1 hour, most of the time is spent compiling the „X11rdp backend“, a specialized X server that is provided by the xrdp project.

Lesen Sie mehr »

Alles Banane!

7. Februar 2015 in GNU/Linux, Technik.

Aus dem Banana Pi Pro Board und einem „Eurobox“ Universal-Gehäuse Polystyrol (EPS), Conrad Artikel-Nr. 523130 – 62 habe ich eine kleine Appliance für mein Netzwerk konstruiert, die verschiedene Aufgaben übernehmen kann. Als Betriebssystem verwende ich Bananian, welches mir ein Debian Wheezy zur Verfügung stellt. Das System war sehr unkompliziert einzurichten und funktioniert super.

Basissystem, autonome Konfiguration

Basissystem, autonome Konfiguration

Die Frontseite. 1 GBE und 2 USB2.0 sind ausgeführt.

Die Frontseite. 1 GBE und 2 USB2.0 sind ausgeführt.

Die von mir ausgewählte Powerbank APC M10BK-EC kann leider kein „Passthrough Charging“, und das saugt! Dass APC diese Funktion nicht zur Verfügung stellt, spricht eine deutliche Sprache über APC. 😛

Im WLAN angemeldet und mit einer Webcam, die ich noch übrig hatte, ergibt sich folgende sehr simple Anwendung:

Beispielkonfiguration mit angeschlossener USB-Kamera

Beispielkonfiguration mit angeschlossener USB-Kamera
Textkonsole auf Android per SSH via USB-Tethering
Textkonsole auf Android per SSH via USB-Tethering

Ich schätze es sehr, dass ich den Krempel aus der mir geläufigen PC-Welt weiterverwenden kann. Das geht mit dieser Konfiguration gut, allerdings zieht die Kiste in oben abgebildeter Webcam-Konfiguration mit aktiviertem WLAN schon gut Strom und wird wohl nur ein paar Stunden durchhalten (Stamina-Test läuft).

Determining The Playtime In Seconds from an OGG Vorbis File

2. Februar 2015 in GNU/Linux, Multimedia, Programmierung.

Problem

To determine the runtime in integer seconds (not including a fractional amount) of a given audio file in format OGG-Vorbis.

This value is required, for example, in the EXTM3U syntax.

Solution

1. Install package vorbis-tools

2. Define this shell function:

ogglength() {
    LANG=C ogginfo "$1" | perl -ne '
        BEGIN { $rv = 1; }
        /Playback length:\s(\d+)m:(\d+)\./ && do {
            print $1*60+$2, "\n";
            $rv = 0;
        };
        END { exit($rv); }
    '
}

3. Use the shell function:

 ~$ ogglength "My File.ogg"
153
 ~$

32bit UEFI Boot on an Intel Baytrail Tablet

30. Januar 2015 in GNU/Linux.

Acer Switch 10 (SecureBoot disabled) loading the experimental Debian Installer for 32bit UEFI Boot by Steve McIntyre ([ISO]).

29.01.15 - 1

So far so good, but the Linux itself has only limited driver support, for example, the keyboard of the docking station does not work (a separately attached USB keyboard does work). Wireless network does not work either. Need customized installation medium or wait for the stuff to become upstream.

Managed to save a dmesg via USB storage, see [DMESG].

References:

Ubuntu 14.10 cryptswap1 With LVM Stops Working After Reboot

15. September 2015 in Administration, GNU/Linux.

Today I rebooted an Ubuntu 14.10 that was set up with LVM and encryption.

It was unable to use the encrypted swapspace cryptswap1, which ultimately halted the boot procedure with a prompt (S for skip and M for manual resolution, i.e. single-user-mode prompt).

The problem appears to be that the UUID (blkid) of the designated swap device is lost (destroyed by overwriting). This may not become apparent after the first reboot, because data actually has to be written to the device in order for the problem to appear. At last that is my working hypothesis on why this did not bite me earlier.

Lesen Sie mehr »

Filtering and Rate-Limiting ICMPv6 on a GNU/Linux Server

25. Januar 2015 in Administration, GNU/Linux.

Introduction

ICMP (Internet Control Message Protocol) in IPv6 is used for a variety of purposes. As opposed to IPv4, support for some of the applications of ICMP by nodes participating in an IPV6 network is mandatory. On the other hand, due to the security-relvant nature of some of the applications, where in IPv4 it may have sufficed to simply allow or disallow all ICMP traffic or certain types of ICMP packages, deeper inspection of ICMP traffic is required in IPv6.

In the following I draft an example of a set of rules for a Linux netfilter firewall on a simple, standalone application server (not a virtualization host).

Lesen Sie mehr »

Support For Multiple Languages in WordPress

28. Juli 2015 in Programmierung, Technik.

Introduction

Foreign visitors have pointed out to me that they sometimes read my blog using translation functions in their their webbrowsing software, most notably „Google Translate“ which is directly built into Google Chrome. That translation function does a good job, but sometimes produces oddities, for example it attempts to translate my lastname, which is also a valid German vocable.

That problem was quickly addressed by adding the class="notranslate" plus the HTML5 language attribute translate="no" to a <span> surrounding my name. But this incident contrasted a deeper problem that has been troubeling me for a while now.

Lesen Sie mehr »