Qubes OS: Connect to Wi-Fi or Ethernet or another network

A couple of days ago we decided to give Qubes OS a go and see what it could do for a regular user. The installation was easy as it uses the same installer as Fedora, so we just created a live USB and formatted a laptop that had built in Wi-Fi.

To our surprise, we could not figure out how to change the network settings and activate an internet connection! Going to the NetworkManager (nm), even with root, would show us all fields as disabled when trying to create any new connection!

Some time passed before we realized that the NetworkManager of XFCE4 was not the way to go. After inspecting the Virtual Machines on the Qubes VM Manager, we saw that the sys-net VM was the only one that had in its hardware settings to access the Ethernet and Wi-Fi modules. So we got the hint, we needed to modify sys-net in order to connect the entire OS with its VMs to the network.

To modify the settings of the sys-net VM we needed access to the Settings Application, which was not available in the application menu. So the first thing we did, was to use the sys-net: Add more shortcuts... option under the group ServiceVM: sys-net to enable the Settings application shortcut.

In the [Dom0] Settings: sys-net window, we went to the Applications tab, on the left list we scrolled down to find the Settings option.

After selecting the Settings option, we clicked on the > button to move the Settings option to the right list.

Then we clicked on the OK button to apply the changes.

Going back to the application menu and the group ServiceVM: sys-net we could see the new option for sys-net: Settings.

Clicking on the sys-net: Settings showed us the usual settings manager for Gnome.

From there on, our job was easy, we just clicked on the Network option that gave us the window to modify all network settings. Then we selected the Wi-Fi network that we wanted to connect to, which worked without a hitch!

Finally, we had to test if the configuration was working as expected. From the application menu, under the group Domain: personal, we selected the option personal: Firefox to start the Firefox application on the personal VM.

Once Firefox started we could see that internet connection was active and everything was working as expected!

Fedora Configure Hardware Acceleration for the Android Emulator

While setting up Android Studio on a Fedora 27 x64, we got the following message from the Android Studio Setup Wizard:

We have detected that your system can run the Android emulator in an accelerated performance mode.
Linux-based systems support virtual machine acceleration through the KVM (Kernel-mode Virtual Machine) software package.

Search for install instructions for your particular Linux configuration (Android KVM Linux Installation) that KVM is enabled for faster Android emulator performance.

After going through the website mentioned in the message we noticed that there were no instructions for Fedora so we decided to write our own.

Below are the steps we followed to enable hardware acceleration for the Android emulator.

Step 1: Verify that your CPU has virtualization extensions.

Execute the following in a terminal:

egrep '^flags.*(vmx|svm)' /proc/cpuinfo;

if you get ANY output then it would mean that your CPU supports either VMX or SVM which is good.
If it does not print anything then the emulator will fall back to software virtualization, which is extremely slow.

Step 2: Install the virtualization packages

sudo dnf group install --with-optional virtualization;

Step 3: Start the service

sudo systemctl start libvirtd;

Step 4: Automatically start the service on boot:

sudo systemctl enable libvirtd;

Step 5: Verify that the kvm kernel modules were loaded

lsmod | grep kvm

If the above command does not print kvm_intel or kvm_amd, it would mean that KVM is not properly configured.

Compiling openbts-umts on Ubuntu 15.04

Below are the steps we followed to compile OpenBTS-UMTS on Ubuntu 15.04.
There could be a chance that we installed a couple of extra system packages while troubleshooting the installation but it works and we did not include some heavy system service as well so it should be OK.

sudo apt-get install build-essential libuhd autoconf libtool libdevel libzmq-dev libzmq libzmq-dev libzmq-dev libosip2-dev libortp-dev libusb-dev libusb-1.0 libtool-bin libsqlite3-dev libboost-dev libreadline-dev;
git clone https://github.com/RangeNetworks/OpenBTS-UMTS;
cd OpenBTS-UMTS/;
git submodule init;
git submodule update;
#First we need to setup ASN1C compiler
tar -xf asn1c-0.9.23.tar.gz;
cd vlm-asn1c-0959ffb/;
make check;
sudo make install;
cd ..;
#Finally, we can proceed with compiling openbts-umts
sudo make install;

Perform diff on two folders

To perform a recursive diff on all the files of two folders we just need to add the -r (or --recursive) parameter that recursively compares any subdirectories found.

To avoid needless messages from the tool, we can also use the -q (or --brief) parameter that reports only when files differ.

Example of performing diff on two folders recursively while preventing needless messages.

diff -rq aFolder someOtherFolder;

Count how many submissions per score

Recently, we had access to a database that contained the scores of a programming competitions system.
The database contained several contests, each contest contained several challenges and any competitor could make multiple submissions.
We wanted to extract a couple of charts showing

  • how many submissions we had per score and
  • how many submissions we had per score while filtering out the best submission (max score) per contestant per challenge per contest

The following code will return the number of submissions per score per challenge per contest.

SELECT contest_id, challenge_id, TRUNCATE(score, 1), COUNT(*)
FROM submissions
GROUP BY contest_id, challenge_id, TRUNCATE(score, 1)
ORDER BY contest_id, challenge_id, TRUNCATE(score, 1);

The next one will return the number of submissions per score per challenge per contest while filtering out the best submission (max score) per contestant per challenge per contest:

SELECT contest_id, challenge_id, TRUNCATE(max_score, 1), COUNT(*)
  SELECT contest_id, challenge_id, competitor_id, MAX(score) AS max_score
  FROM submissions
  GROUP BY contest_id, challenge_id, competitor_id
) AS max_scores
GROUP BY contest_id, challenge_id, TRUNCATE(max_score, 1)
ORDER BY contest_id, challenge_id, TRUNCATE(max_score, 1);

Compiling gr-gsm on Ubuntu 14.04 LTS

Below are the steps that we followed to compile gr-gsm on Ubuntu 14.04 LTS.

sudo apt-get update;
sudo apt-get install build-essential python-dev git python-pip;
sudo pip install PyBOMBS;
sudo pybombs prefix init /usr/local -a default_prx;
sudo pybombs config default_prefix default_prx;
sudo pybombs recipes add gr-recipes git+https://github.com/gnuradio/gr-recipes.git;
sudo pybombs recipes add gr-etcetera git+https://github.com/gnuradio/gr-etcetera.git;
sudo pybombs install gr-gsm;
sudo ldconfig;

Building wireshark-2.4.2 on CentOS 7 (64bit)

Recently we were trying to compile WireShark from source on a CentOS 7 (64bit) with GTK3 disabled (./configure --disable-gtk3;).

As seen in the truncated logs below we got some errors.
To resolve them we had to install a few packages using yum.
Specifically, our solution involved the installation of the following:

sudo yum install libgcrypt-devel qt5-qttools-devel libpcap-devel -y;

Truncated logs:

checking for libgcrypt-config... no
checking for LIBGCRYPT - version >= 1.4.2... no
configure: error: libgcrypt not found; install libgcrypt-devel package for your system
libgcrypt-devel.i686 libgcrypt-devel.x86_64 
[[email protected] wireshark-2.4.2]$ sudo yum install libgcrypt-devel -y

checking for lrelease-qt5... no
checking for lrelease... no
configure: error: I couldn't find lrelease-qt5 or lrelease; make sure it's installed and in your path
[[email protected] wireshark-2.4.2]$ sudo yum install qt5-qttools-devel

checking whether to use libpcap for packet capture... yes
checking for pcap-config... no
checking for extraneous pcap header directories... not found
checking pcap.h usability... no
checking pcap.h presence... no
checking for pcap.h... no
configure: error: Header file pcap.h not found; if you installed libpcap
from source, did you also do "make install-incl", and if you installed a
binary package of libpcap, is there also a developer's package of libpcap,
and did you also install that package?
[[email protected] wireshark-2.4.2]$ sudo yum install libpcap-devel

[[email protected] wireshark-2.4.2]$ ./configure --disable-gtk3


Words of wisdom from a Peon of the Orc Horde (Warcraft III) for Interns

Examples of proper communication etiquette: things that are good to say to your colleagues during your internship:

Scenario 1: When you have free time or you delivered all your tasks:

Ready to work.

Something need doing?

Scenario 2: When a colleague wants to talk to you:



What do you want?

Scenario 3: Accepting a task:

I can do that.

Be happy to.

Work work.

Okey dokey.

I’ll try…


Why not?

Scenario 4: Rejecting a task:

Me busy. Leave me alone!

No time for play.

Me not that kind of orc!

Scenario 5: Rejecting a task:



Copyright Notice:

Warcraft® III: Reign of Chaos®
©2002 Blizzard Entertainment, Inc. All rights reserved. Reign of Chaos, Warcraft and Blizzard Entertainment are trademarks or registered trademarks of Blizzard Entertainment, Inc. in the U.S. and/or other countries.
Warcraft® III: The Frozen Throne®
©2003 Blizzard Entertainment, Inc. All rights reserved. The Frozen Throne, Warcraft and Blizzard Entertainment are trademarks or registered trademarks of Blizzard Entertainment, Inc. in the U.S. and/or other countries.

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Converting a (void*) buffer to a std::vector

On a project we were recently working on, some legacy C code was producing a (void*) voidBuffer accompanied by its size.
The rest of the project was in C++ and we needed to convert the (void*) voidBuffer to a std::vector<unsigned char> vector.

To do so, we used the following code:

//First cast the (void *) voidBuffer to an (unsigned char *) to implicitly get the element size (1 Byte each)
const unsigned char *charBuffer = (unsigned char *) voidBuffer;
//Then we create the vector (named vectorBuffer) by copying the contents of charBuffer to the vector
std::vector<unsigned char> vectorBuffer(charBuffer, charBuffer + length);

Converting a (void*) buffer to a std::vector Example (compressed) (5 downloads)