solving standby wifi problems on my ubuntu 16.04


Sometimes, really just sometimes, my WIFI was not working after resuming my thinkpad from standby. I have Ubuntu 16.04 running as OS.

Two things (mostly one of them) always helped:

sudo su
rfkill unblock wlan 
/etc/init.d/network-manager restart

Because i love it to automate things i wrote a tiny script:

fly3rman@flybookx:/lib/systemd/system-sleep$ cat networkmanager_restart 
if [ $1 = post ] 

then rfkill unblock wlan && /etc/init.d/network-manager restart

do not forget to make it executable:

fly3rman@flybookx:/lib/systemd/system-sleep$ sudo chmod a+x networkmanager_restart 

Because the WIFI connection need to be reestablished after standby anyway, it doesn’t hurt :p

convert a hyper-v .vhdx file to .vmdk for virtualbox

With the version 5.0.16 it is not possible to convert a .vhdx to .vmdk or an another readable image format for virtualbox. Here is the bug report (link). It throws errors like:

 VHDX: Can not load the image because both headers are corrupt (VERR_VD_GEN_INVALID_HEADER).

With version 4.3 (download) it does work, so you have to downgrade.

 C:\Program Files\Oracle\VirtualBox>VBoxManage clonehd "W:\home.vhdx" --format VM DK "w:\home\home.vmdk" 0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100% Clone hard disk created in format 'VMDK'. UUID: d94494ad-be8f-472e-af6a-c10b5275872b


Shutdown Virtualbox machines on windows host shutdown or restart

You dont want to manual shutdown or save your virtualbox virtual machines when you need to reboot your windows host? Here is a solution:
Create a .bat file with the following content, replace <vm-name> with the the name of the virtual machine. Order your machines properly, for example shut down your application before the database server it uses.

 @echo off "C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" controlvm <vm-name> savestate "C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" controlvm icinga-vm01 savestate "C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" controlvm db-vm01 savestate "C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" controlvm home savestate

Run in start menue or cmd.exe: gpedit.msc. Goto computer configuration -> windows-settings -> scripts (start/shutdown) and double click on shutdown.


gruppenrichtlinieneditor script 2

Add your previously created batch file here.… weiterlesen

Korad KA3005 Labview Software

In the need of an constant voltage/current power supply. Requirements and usage scenarios were:

  • Testing LEDs. For this i need a constant current (CC) source. Important here was to have 4 „digits“. In this case it means i can set something like 0.003 Amper. So this power supply allows you control the current as fine as 1 mA.
  • More than 3A current for feeding my LIPO charger. In this case it provides 5 A.
  • 0-30 V is sufficient to power all common voltages like 3.3/5/12/24 V. Also higher voltage means higher power for my LIPO charger. In this case 150 W.

New toy – ESP8266 in Arduino- or mini-format, with more shields to come!

Recently i have discovered this module NodeMCU Development board and of course ordered one. It is waiting for me at the postal office. But i talk about it another time. The cool thing about it: you can programm it with the Arduino-IDE:

Yesterday i discovered an another cool toy on reddit:wemos mini d1

Wemos D1 and Wemos D1 mini. The first is an Arduino-Size ESp8266 Board. The second is a mini version with it. Both also programmable with the Arduino IDE, like described here:

But the coolest thing about it: shields. You already can order the Wemos D1 mini with and DHT11 Shield for silly 6$ (we really need an stronger € again ;]).… weiterlesen

Dnsmasq Ubuntu 15.04 with FritzBox for PXE

I run dnsmaq on a virtual machine as a dhcp relay with additional PXE-boot information and as a PXE/TFTP-Server, because my Fritzbox does not allow to configure addtional DHCP-stuff.
Here is a small howto and a problem i ran into.

First, install dnsmasq:

sudo apt-get install dnsmasq

Here a working configuration file, edit you ip range:

fly3rman@pixi:~$ cat /etc/dnsmasq.conf
pxe-service=X86PC,     "Legacy Netzwerkboot", /tftpboot/pxelinux
pxe-service=X86-64_EFI,"EFI Netzwerkboot",    /tftpboot/pxelinux

So far fine, but the vm itself could not resolve any hostnames while dnsmasq was running. Afiter i checked the dynamic /etc/resolve.conf, i found the problem.… weiterlesen

syncthing on ubuntu 15.04

Recently i started to use Syncthing instead of Bittorrent Sync. I like it so far =)

Here is a small tutorial how to install syncthing on an Ubuntu 15.04 with systemd daemon for automatic start on boot:

First of all download and extract:

cd ~

create directory and extract it, change user@user here:

mkdir /opt/syncthing
chown user@user /opt/syncthing
sudo tar xf syncthing-linux-amd64-v0.10.31.tar.gz --strip-components=1 -C /opt/syncthing2

copy systemd unit:

cp /opt/syncthing/etc/linux-systemd/system/syncthing@.service /lib/systemd/system/syncthing@.service

edit the file:

 sudo nano /lib/systemd/system/syncthing@.service

Change the „ExecStart“ line to:

ExecStart=/opt/syncthing/syncthing -no-browser -logflags=0 -home=/opt/syncthing/config

-home=/opt/syncthing/config is optional and tells syncthing to use this directory for the config files instead of /home/$user/.config/syncthing

Enable and start the service:

systemctl enable syncthing@user.service
systemctl start syncthing@user.service

Reboot and try.… weiterlesen