Posts Tagged ‘ubuntu linux’

Alternative way to enter as administrator in MySQL if you forgot MySQL root password on Debian Linux

Wednesday, July 10th, 2013

Forgot MySQL password root alternative way to enter as administrator in MyQL MySQL logo with 2 dolphins

Whether you have to administrate a bunch of chaotic organized MySQL servers and amount of work is more than you can bear it is very common you make stupid mistakes, like loosing MySQL root adminsitrator password. There is way to recover password by stopping SQL server and starting it with –skip-grant-tables options via SSH , however if you do it that way there is at least few seconds of down time and as its not a good idea on productive servers Debian and Ubuntu Linux admins have better way to do it by using MySQL default user used to check whether all is fine with database on MySQL server initialization via /etc/init.d/mysql. User with GRANT PRIVILEGES, (all MySQL administrator users have grant privileges) on Debian based distributions is debian-sys-maint and whether you have root access to server you can easily obtain password with:

# grep -i -E 'user|pass' /etc/mysql/debian.cnf |uniq

user = debian-sys-maint

password = k6x6tBUBfHN3ZxHv

Using this password then you can login via mysql cli or via PhpMyAdmin, whether installed and do any normal SQL operation you do as root. Of course having this password in plain text file can be very dangerous, by default it is configured to be only red by root be careful not to change this permissions by default as anyone who has access to system can then access your SQL as administrator.
To reset MySQL root password once logged in run:

UPDATE USER set password=PASSWORD('NEW_PASS_WORD') where USER='root';

Enjoy 😉

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ZenMap Nmap multi platform Graphical frontend for checking port security

Saturday, June 15th, 2013

graphic program to scan remote network server port security on GNU Linux and Windows ZenMap

Recently I wrote little article with some examples for scanning server port security with Nmap. I forgot to mention in the article that there is also Nmap frontend GUI program called ZenMap. ZenMap port is available for both Windows and Linux. In Debian, Ubuntu, Mint and other debian derivative distributions ZenMap is available from standard package repositories;

 noah:~# apt-cache show zenmap|grep -i description -A 3

Description-en: The Network Mapper Front End
 Zenmap is an Nmap frontend. It is meant to be useful for advanced users
 and to make Nmap easy to use by beginners. It was originally derived
 from Umit, an Nmap GUI created as part of the Google Summer of Code.
Description-md5: 4e4e4c6aeaa4441484054473e97b7168
Tag: implemented-in::python, interface::x11, network::scanner, role::program,
 uitoolkit::gtk, use::scanning, x11::application
Section: net

To install  ZenMap on Debian / Ubuntu Linux:

noah:~# apt-get install --yes zenmap

In Fedora, CentOS and other RPM based Linux-es to install ZenMap run:

noah:~# yum -y install nmap-frontend nmap

To use Nmap's Frontend full functionality, you have to run it as (root) superuser:

hipo@noah:~$ sudo su
[sudo] password for hipo:
noah:~# zenmap

Zenmap saves, a lot of time as there is no need to  remember Nmap's arguments or run few Nmap scans until you get essential information for remote scanned machine.
It automatically gives details on Remote server running services (fingerprint)

Zenmap remote server security services scan with services software version

Very useful report it makes as well is network (and host) topology diagram,

network scanner remote host Linux Windows toplogy guess ZenMap screenshot

ZenMap is just Nmap frontend and under the GUI it does use Nmap with various arguments to do produce scan results. In Nmap Output tab, you can see a lot of verbose info.

Zenmap Linux Windows GUI port scanne  nmap output tab screen Debian / Ubuntu Linux

Happy scanning 🙂

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Converting jpeg / png pictures to mp4 format videos on Linux with avconv

Wednesday, June 12th, 2013

making mp4 videos from jpeg and png pictures gnu linux
Here in my job, there is one internet (TV) around which can only read video formats in Mp4. Henceforth I needed a way to convert a number of JPEG / PNG format Picture files to Mp4. In my situation I needed to make video out of pictures and script it as this was required to be later pushed via FTP protocol to the Internet TV. Ater doing some research I figured out this is possible to build video out of pictures by using together ImageMagick and avconv.

First thing is to send pictures in certain resolution. There is a tool from imagemagick package called mogrify (which can do that). To convert a number of different dimension pictures to lets say 1024×768, used:

noah:~# mogrify -resize 1024×768 *.png

In earlier Linux distributions to create a movie from pictures ffmpeg was used like so:

# ffmpeg -qscale 5 -r 20 -b 9600 -i SDC%04d.png movie.mp4

However in newer version of ffmpeg support for this is removed, and to make video from images, there is other tool avconv. On most Linux distributions avconv is part of libav-tools package.

To install on avconv Debian and Ubuntu;
noah:~# apt-get install –yes libav-tools

Once installed to create single mp4 video from JPEG or PNG pictures:

noah:~# avconv -i SDC106001.JPG SDC10595.JPG SDC13611.JPG SDC13612.JPG SDC13614.JPG  movie-from-pictures.mp4

I found there is also a nice GUI,software Open Movie Editor, which can create video out of number of pictuers stored in a directory. 
Open Movie Editor is available in most Linux distributions (unfortunately as of time of writting on Debian Wheeze there is no install candidate of openmovieeditor), there is however substitute package doing the same job called openshot);
On latest Debian stable to install Openshot:

noah:~# apt-get install –yes openshot

openshot running on Debian Wheezy Linux create video from pictures

Openshot has an option (Import Image Sequence) from File -> Import Image Sequence. Using this option you can select a directory with fles with common prefix name lets say IMG*.png and create Video based on the photos inside.

Linux create  video from images import image sequence Debian / Fedora and Ubuntu

On Ubuntu Linux or other distro where openmovieeditor is avialable install it with:

ubuntu:~# apt-get install –yes openmovieeditor

Openmovieeditor Linux create movies from images screenshot
To create a video out of pictures click on Media Browser tab. Choose the Folder with pictures from which video will be generated and drag them to the Video bar

To save produced video navigate to menus:

Project -> Render

and select format to save it as. One good codec to save output is Quicktime's. To convert later Quicktime MOV Video to MP4 video,
there is the  Pytube Media Converter script.

Well that's all enjoy your new videos from pictures 🙂

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Remove password prompt on GNOME Shutdown / Restart on Debian and Ubuntu Linux

Saturday, June 1st, 2013

It is ultra annoying, that in newest Debian and Ubuntu releases with GNOME 3 Desktop environment on every shutdown or restart you need to type in Super User (root) password, to authorize shutdown / restart.

Generally prompting for root password on GNOME restart is obviously a good think from security point of view, but from usability one – especially on notebooks it is useless annoyance…

So after changing this behavior I came up with this tiny article on how to get rid of GNOME Shutdown / Restart password prompt.

There is a click button (on left of Auth prompt on Shutdown showing URL to XML policy rule from where this behavior is controlled. A really good hint to where to look for to change those annoying behavior…

 Here is how to change this new annoying behavior to old GNOME 2 default restart with no root password prompt .
linux:~# gedit /usr/share/polkit-1/actions/org.freedesktop.consolekit.policy

Find in XML source sections:

Restart the system when multiple users are logged in System policy prevents restarting the system when other users are logged in no auth_admin_keep
Stop the system when multiple users are logged in System policy prevents stopping the system when other users are logged in no auth_admin_keep

To change Restart and Shutdown GUI behavior to not prompt for password, you need to modify in above code:



After changes both sections should look like so:

<action id="org.freedesktop.consolekit.system.restart">
<description>Restart the system</description>
<message>System policy prevents restarting the system</message>

<action id="org.freedesktop.consolekit.system.restart-multiple-users">
<description>Restart the system when multiple users are logged in</description>
<message>System policy prevents restarting the system when other users are logged in</message>

That's all you finally get rid of the annoying prompt for root password. Enjoy 🙂

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Fixing insserv: warning: script ‘…’ missing LSB tags and overrides on Debian and Ubuntu Linux

Friday, April 12th, 2013

apt-get f install logo fixing warning script missing LSB tags Debian Ubuntu Linux

Some of packages I just tried to install on one of the Debian servers I admin failed during package (set up) configuration stage. Here is little paste with the errors due to it dpkg-reconfigure on each of newly set-up packages failed:

Setting up acct (6.5.4-2.1) ...
insserv: warning: script 'K02courier-imap' missing LSB tags and overrides
insserv: warning: script 'courier-imapd' missing LSB tags and overrides
insserv: warning: script 'iptables' missing LSB tags and overrides
insserv: warning: script 'courier-imap' missing LSB tags and overrides 

Because of this whole package install failed and the usual

# apt-get -f install

supposed to fix mess with packages end up with same errors:

insserv: warning: script 'K02courier-imap' missing LSB tags and overrides
insserv: warning: script 'iptables' missing LSB tags and overrides
insserv: warning: script 'courier-imap' missing LSB tags and overrides
insserv: There is a loop between service watchdog and iptables if stopped
insserv:  loop involving service iptables at depth 2
insserv:  loop involving service watchdog at depth 1
insserv: Stopping iptables depends on watchdog and therefore on system facility `$all' which can not be true!
insserv: exiting now without changing boot order!
update-rc.d: error: insserv rejected the script header
dpkg: error processing acct (--configure):
 subprocess installed post-installation script returned error exit status 1

he scripts in question iptables / courier-imap / K02courier-imap were custom created  scripts by me earlier and I have completely forgot about it. In Debian 5 and earlier I used the same scripts to make system load custom services not installed through a standard Debian package. After a bit of research, I've noticed in newer Debian / Ubuntu release, new Commented tags are included in all Debian belonging packages init scripts. Thus the reason for failing package configuration, were my custom scripts were missing those tags. To get around the situation I had to open manually each of the scripts missing init script LSB tags i.e. ( iptables / courier-imap / K02courier-imap ) and add after
#! /bin/sh


# Provides:          skeleton
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Example initscript
# Description:       This file should be used to construct scripts to be
#                    placed in /etc/init.d.

Once those "boilerplate", skele comments are included to solve the mess I had to run again:

# apt-get -f install

This solves it. Enjoy 🙂

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How to change hostname permanently on Debian and Ubuntu Linux

Thursday, March 14th, 2013

Change hostname on Debian and Ubuntu Linux terminal hostname screenshot

I had to configure a newly purchased dedicated server from UK2. New servers cames shipped with some random assigned node hostname  like server42803. This is pretty annoying, and has to be changed especially if your company has a naming server policy in some format like; company-s1#, company-s2#, company-sN#.

Changing hostname via hosts definition file /etc/hosts to assign the IP address of the host to the hostname is not enough for changing the hostname shown in shell via SSH user login.

To display full hostname on Debian and Ubuntu, had to type:

server42803:~# hostname

To change permanently server host to lets say company-s5;

server42803:~# cat /etc/hostname | \
sed -e '' > /etc/hostname

To change for current logged in SSH session:

server42803:~# hostname company-s5

Finally because already old hostname is red by sshd, you have to also restart sshd for new hostname to be visible on user ssh:

company-s5:~# /etc/init.d/ssh restart

As well as run script:

company-s5:~# /etc/init.d/

Mission change host accomplished, Enjoy 🙂

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How to disable PC Spaker on Debian and Ubuntu Linux

Sunday, May 13th, 2012


How to disable pc-speaker on Linux / PC-Speaker Old Desktop Computer picture

A PC Speaker is helpful as it could be used as a tool for diagnosing system hardware failures (different systems produce different beep sequences depending on the machine BIOS type).
Using the instructions for the respective BIOS vendor and version one could determine the type of problem experienced by a machine based on the sequence and frequency of sounds produced by the SPEAKER.
Lets say a hardware component on a server is down with no need for a monitor or screen to be attached you can say precisely if it is the hard drive, memory or fan malfunctioning…

Generally speaking historically embedded PC Speaker was inseparatable part of the Personal Computers, preceding the soundblasters, now this is changing but for compitability sake many comp equipment vendors still produce machines with pc-speaker in.
Some newer machines (mostly laptops) are factory produced with no PC-SPEAKER component anymore.
For those who don't know what is PC SPEAKER, it is a hardware device capable of emitting very simple short beep sounds at certain system occasions.

Talking about PC-Speaker, it reminds me of the old computer days, where we used pc-speakers to play music in DOS quite frequently.
It was wide practice across my friends and myself to use the pc-speaker to play Axel Folly and other mod files because we couldn't afford to pay 150$ for a sound cards. Playing a song over pc-speaker is quite a nice thing and it will be a nice thing if someone writes a program to be able to play songs on Linux via the pc-speaker for the sake of experiment.

As of time of writting, I don't know of any application capable of playing music files via the pc-speaker if one knows of something like this please, drop me a comment..

As long as it is used for hardware failure diagnosis the speaker is useful, however there are too many occasions where its just creating useless annoying sounds.
For instance whether one uses a GUI terminal or console typing commands and hits multiple times backspace to delete a mistyped command. The result is just irritating beeps, which could be quite disturbing for other people in the room (for example if you use Linux as Desktop in heterogeneous OS office).
When this "unplanned" glitchering beeps are experienced 100+ times a day you really want to break the computer, as well as your collegues are starting to get mad (if not using their headphones) 🙂

Hence you need sometimes to turn off the pc-speaker to save some nerves.

Here is how this is done on major Linux distros.

On Debian and most other distros, the PC SPEAKER is controlled by a kernel module, so to disable communication with the speaker you have to remove the kernel module.

On Debian and Fedora disabling pcspeaker is done with:

# modprobe -r pcspkr

Then to permanently disable load of the pcspkr module on system boot:

debian:~# echo 'blacklist pcspkr' >> /etc/modprobe.d/blacklist.conf

On Ubuntu to disable load on boot /etc/modprobe.d/blacklist, file should be used:

ubuntu:~# echo 'blacklist pcspkr' >> /etc/modprobe.d/blacklist
Well that's all folks …

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How to make screenshot in /dev/tty console on GNU / Linux – Taking picture JPEG / PNG snapshot of text console in systems without graphical environment

Monday, April 30th, 2012

I'm used to making picture screenshots in GNOME desktop environment. As I've said in my prior posts, I'm starting to return to my old habits of using console ttys for regular daily jobs in order to increase my work efficiency. In that manner of thoughts sometimes I need to take a screenshot of what I'm seeing in my physical (TTY consoles) to be able to later reuse this. I did some experimenting and this is how this article got born.

In this post, I will shortly explain how a picture of a command running in console or terminal in GNU / Linux can be made

Before proceeding to the core of the article, I will say few words on ttys as I believe they might be helpful someone.
The abbreviation of tty comes after TeleTYpewritter phrase and is dating back somewhere near the 1960s. The TTY was invented to help people with impaired eyesight or hearing to use a telephone like typing interface.

In Unix / Linux / BSD ttys are the physical consoles, where one logs in (typing in his user/password). There are physical ttys and virtual vtys in today *nixes. Today ttys, are used everywhere in a modern Unixes or Unix like operating system with or without graphical environments.
Various Linux distributions have different number of physical consoles (TTYs) (terminals connected to standard output) and this depends mostly on the distro major contributors, developers or surrounding OS community philosophy.
Most modern Linux distributions have at least 5 to 7 physical ttys. Some Linux distributions like Debian for instance as of time of writting this, had 7 active by default physical consoles.
Adding 3 more ttys in Debian / Ubuntu Linux is done by adding the following lines in /etc/inittab:

7:23:respawn:/sbin/getty 38400 tty7
8:23:respawn:/sbin/getty 38400 tty8
9:23:respawn:/sbin/getty 38400 tty9

On some Linux distributions like Fedora version 9 and newer ones, new ttys can no longer be added via /etc/inittab,as the RedHat guys changed it for some weird reason, but I guess this is too broad issue to discuss ….

In graphical environments ttys are called methaphorically "virtual". For instance in gnome-terminal or while connecting to a remote SSH server, a common tty naming would be /dev/pts/8 etc.

tty command in Linux and BSDs can be used to learn which tty, one is operating in.

Here is output from my tty command, issued on 3rd TTY (ALT+F3) on my notebook:

noah:~# tty

A tty cmd output from mlterm GUI terminal is like so:

hipo@noah:~$ tty/dev/pts/9

Now as mentioned few basic things on ttys I will proceed further to explain how I managed to:

a) Take screenshot of a plain text tty screen into .txt file format
b) take a (picture) JPG / PNG screenshot of my Linux TTY consoles content

1. Take screenshot of plain text tty screen into a plain (ASCII) .txt file:

To take a screenshot of tty1, tty2 and tty3 text consoles in a txt plain text format, cat + a standard UNIX redirect is all necessery:

noah:~# cat /dev/vcs1 > /home/hipo/tty1_text_screenshot.txt
noah:~# cat /dev/vcs2 > /home/hipo/tty2_text_screenshot.txt
noah:~# cat /dev/vcs3 > /home/hipo/tty3_text_screenshot.txt

This will dump the text content of the console into the respective files, if however you try to dump an ncurses library like text interactive interfaces you will end up with a bunch of unreadable mess.
In order to read the produced text 'shots' onwards less command can be used …

noah:~# less /home/hipo/tty1_text_screenshot.txt
noah:~# less /home/hipo/tty2_text_screenshot.txt
noah:~# less /home/hipo/tty3_text_screenshot.txt

2. Take picture JPG / PNG snapshot of Linux TTY console content

To take a screenshot of my notebook tty consoles I had to first install a "third party program" snapscreenshot . There is no deb / rpm package available as of time of writting this post for the 4 major desktop linux distributions Ubuntu, Debian, Fedora and Slackware.
Hence to install snapscreenshot,I had to manually download the latest program tar ball source and compile e.g.:

noah:~# cd /usr/local/src
noah:/usr/local/src# wget -q
noah:/usr/local/src# tar -jxvvvf snapscreenshot-

noah:/usr/local/src# cd snapscreenshot-
noah:/usr/local/src/snapscreenshot-1.0.14# ./configure && make && make install
Fine. Done. make.
make: Nothing to be done for `all'.
if [ ! "/usr/local/bin" = "" ]; then mkdir –parents /usr/local/bin 2>/dev/null; mkdir /usr/local/bin 2>/dev/null; \
for s in snapscreenshot ""; do if [ ! "$s" = "" ]; then \
install -c -s -o bin -g bin -m 755 "$s" /usr/local/bin/"$s";fi;\
done; \
fi; \
if [ ! "/usr/local/man" = "" ]; then mkdir –parents /usr/local/man 2>/dev/null; mkdir /usr/local/man 2>/dev/null; \
for s in snapscreenshot.1 ""; do if [ ! "$s" = "" ]; then \
install -m 644 "$s" /usr/local/man/man"`echo "$s"|sed 's/.*\.//'`"/"$s";fi;\
done; \

By default snapscreenshot command is made to take screenshot in a tga image format, this format is readable by most picture viewing programs available today, however it is not too common and not so standartized for the web as the JPEG and PNG.
Therefore to make the text console tty snapshot taken in PNG or JPEG one needs to use ImageMagick's convert tool. The convert example is also shown in snapscreenshot manual page Example section.

To take a .png image format screenshot of lets say Midnight Commander interactive console file manager running in console tty1, I used the command:

noah:/home/hipo# snapscreenshot -c1 -x1 > ~/console-screenshot.tga && convert ~/console-screenshot.tga console-screenshot.png

Linux text console tty mc screenshot with snapscreenshot terminal / console snapshotting program

Note that you need to have read/write permissions to the /dev/vcs* otherwise the snapscreenshot will be unable to read the tty and produce an error:

hipo@noah:~/Desktop$ snapscreenshot -c2 -x1 > snap.tga && convert snap.tga snap.pngGeometry will be: 1x2Reading font…/dev/console: Permission denied

To take simultaneous picture screenshot of everything contained in all text consoles, ranging from tty1 to tty5, issue:

noah:/home/hipo# snapscreenshot -c5 -x1 > ~/console-screenshot.tga && convert ~/console-screenshot.tga console-screenshot.png

Here is a resized 480×320 pixels version of the original screenshot the command produces:

All text Consoles tty1 to tty5 merged screenshot png image with snapscreenshot taken on Debian GNU / Linux

Storing a picture shot of the text (console) screen in JPEG (JPG) format is done analogously just the convert command output extension has to be changed to jpeg i.e.:

noah:/home/hipo# snapscreenshot -c5 -x1 > ~/console-screenshot.tga && convert ~/console-screenshot.tga console-screenshot.jpeg

I've also written a tiny wrapper shell script, to facilitate myself picture picture taking as I didn't like to type each time I want to take a screenshot of a tty the above long line.

Here is the wrapper script I wrote:

### Config
# .tga produced file name
# gets current date
cur_date=$(date +%d_%m_%Y|sed -e 's/^ *//');
# png output f name
### END Config
snapscreenshot -c$arg1 -x1 > $output_f_name && convert $output_f_name $png_f_name;
echo "Output png screenshot from tty1 console produced in";
echo "$PWD/$png_f_name";
/bin/rm -f $output_f_name;

You can also download my snapscreenshot wrapper script here

The script is quite simplistic to use, it takes just one argument which is the number of the tty you would like to screenshot.
To use my script download it in /usr/local/bin and set it executable flag:

noah:~# cd /usr/local/bin
noah:/usr/local/bin# wget -q
noah:/usr/local/bin# chmod +x

Onwards to use the script to snapshot console terminal (tty1) type:


I've made also mirror of latest version of snapscreenshot- here just in case this nice little program disappears from the net in future times.


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How to upgrade single package with their dependencies on Debian and Ubuntu Linux

Friday, March 16th, 2012

Debian GNU / Linux apt-get upgrade a package selection of a whole bunch of packages ready to upgrade apt artistic logo

Are you a Debian System Administrator and you recently run apt-get upgrade && apt-get upgrade finding out there are plenty of new packagesfor upgrade? Do you need only a pre-selected number of packages to upgrade with apt?
I run apt-get update && apt-get upgrade on one of our company Debian servers, just to see there are a number of packages to be upgraded among which there was some I didn't wanted to upgrade. Here is a little paste output from apt-get upgrade:

debian:~# apt-get update && apt-get upgrade
Hit squeeze/updates Release.gpg
Hit squeeze/updates/main amd64 Packages
Fetched 128 kB in 0s (441 kB/s)
Reading package lists... Done
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
at imagemagick libdbd-pg-perl libfreetype6 libmagickcore3 libmagickcore3-extra libmagickwand3 libmysqlclient16 mysql-client
mysql-client-5.1 mysql-common mysql-server mysql-server-5.1 mysql-server-core-5.1
Do you want to continue [Y/n]
14 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

From first sight it seems logical to issue apt-get upgrade packagename to upgrade only single package with its package dependencies, instead of the whole group the above packs. However doing:
apt-get upgrade imagemagick will still try to upgrade all the packages instead of just imagemagick and its dependency package deb libmagickcore3

debian:~# apt-get upgrade imagemagick
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
at imagemagick libdbd-pg-perl libfreetype6 libmagickcore3 libmagickcore3-extra libmagickwand3 libmysqlclient16 mysql-client
mysql-client-5.1 mysql-common mysql-server mysql-server-5.1 mysql-server-core-5.1
14 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Do you want to continue [Y/n]

Doing all package,upgrade is not a good idea in my case, since upgrading mysql-server will require a MySQL server restart (something which we cannot afford to do right now) on this production server.
MySQL server restart during upgrade is never a good idea especially on productive busy (heavy loaded) SQL servers.
A restart of the MySQL server serving thousands of requests per second could lead often to crashed tables and hence temporary server downtime etc.

Still it is a good idea to upgrade the rest of packages with their newer versions. For exmpl. to upgrade; imagemagick, at , libfreetype6 and so on.

In order to upgrade only this 3 ones and their respective package dependencies, issue:

debian:~# apt-get --yes install imagemagick at libfreetype6

Repeat the apt-get install command with passing all the single package name you want to be upgraded and voila you're done :).
Be sure the apt-get install packagename upgrade doesn't require also upgrade of myssql-server, mysql-client, mysql-common or mysql-server-core-5.1 or any of the package name you want to preserve from upgrading.

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