Posts Tagged ‘org’

CentOS 8 / Redhat 8 insert additional guests additions to VM to enable Fullscreen, Copy / Paste and Shared Folder from host OS

Monday, January 10th, 2022


My experience with enabling virtualbox additions guest tools on many of the separate Linux distributions throughout time is pretty bad as it always is a pain in the ass to enable fully functional full screen and copy paste for Virtualbox…
For those who installed it for a first time vbox guest addition tools for Virtualbox are additional software components added so the Emulated Operating system
could allow better screen resolution and better mouse integration support.

So far I've installed virtualbox additions tools to CentOS 7 and Debian Linux various releases and faced complications there as well.
Few days ago my colleague Georgi Stoyanov have installed CentOS 8.3 with current version of VirtualBox 6.1 (vesrsion from beginning of 2022) and he has also shared had issues with enabling the CentOS 8.3 Linux to work with guestadditions but eventually found a resolution.

Thus he has shared with me the solution and I share it with you, so hopefully someone else could enable Guesttools on his CentOS 8.3 with less digging online.
The error received is:

# ./

Trying to install Guest Additions in RHEL 8.3.

VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel
modules. This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup
VirtualBox Guest Additions: or
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup all
VirtualBox Guest Additions: Building the modules for kernel

VirtualBox Guest Additions: Look at /var/log/vboxadd-setup.log to find out what
went wrong
ValueError: File context for /opt/VBoxGuestAdditions-6.0.20/other/mount.vboxsf already defined
VirtualBox Guest Additions: Running kernel modules will not be replaced until
the system is restarted
Press Return to close this window…

No idea what to do next. Been trying for sometime.

To enable guestaddtions in CentOS 8.3, e.g. get arount the error you have to:

1. Install all necessery dependncies RPMs required by GuestAddition tools


# dnf install tar bzip2 kernel-devel-$(uname -r) kernel-headers perl gcc make elfutils-libelf-devel

# dnf -y install gcc automake make kernel-headers dkms bzip2 libxcrypt-compat kernel-devel perl

2.  Run below semanage and restorecon commands


# semanage fcontext -d /opt/VBoxGuestAdditions-/other/mount.vboxsf
# restorecon /opt/VBoxGuestAdditions-/other/mount.vboxsf


3.  Insert Virtualbox guest additions ISO and Run it



Devices -> Insert Guest Additions CD Image


Click Run button to exec Vbox_GAs_6.0.18 script or run it manually


or mount it manually with mount command and execute the to do so:


$ cd /run/media/`whoami`/VB*
$ su
# ./
Installing additional modules …
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel modules.  This may take a while.
VirtualBox Guest Additions: Running kernel modules will not be replaced until the system is restarted
VirtualBox Guest Additions: Starting.


4. Reboot the VM

# reboot

5. Check and Confirm Virtualbox guest additions are properly installed and running

# lsmod | grep vbox


6. Enable Copy / Paste from to Virttual Machine e.g. Shared Clipboard / Shared Folder etc.




The three options most useful besides the support for FullScreen OS emulation by Virtualbox to enable right after
guesttools is on are:

1. Devices -> Shared Clipboard -> Bidirectional
2. Devices -> Drag and Drop -> Bidirectional
3. Devices -> Shared Folders -> Shared Folder Settings


Feast of Saint Naum of Ohrid, One of the Holy Seven Apostoles and Enlighteners of Bulgaria and Slavonic Eastern Orthodox Churches venerated 23 December

Tuesday, December 28th, 2021

In Bulgarian Orthodox Church the feast of Saint Naum of Ohrid is marked right at the end of the Christmas Fasting Period only days before Nativity (nasci, which means "to be born.",  source, Latin nātīvitās (“birth”). See also naïveté, γέννηση (Greek)as known in the East or Christmas (Christ-Mass) or XMas, the "X" comes from the Greek letter Chi,as known in the West. 
The reason to celebrate saint Naum are twofold second, first is the fact he passed away on 23 of December year 910, and second with the aim is to underline the importance of his many translation works for the Cyrillic Medieval Enlightenment Renessance for Europe and Asian Lands thorough the many Bulgarian saints stemming from Saint Cyril and Methodius.


Saint Seven Apostles contemporary Mosaic Saint Sofia Church, Sofia Capital of Bulgaria

The enlightement spreading the new translated understandable texts for the Slavonic "Sea" of people and even in far asia for Slavs and respectively the Slavonic Churches, the biggest member of which is now the Russian Orthodox Church and through later through Orthodox Russia enlightened with Holy Orthodoxy Asia (China, Japan) and Africa. Back then among 1/3 of all the civillized world has been in contact or can speak some form of slavonic and the fact that the Holy Bible, and the Church books were translated for the Slavs has been unthinkably great.Today among 1/10 of the world still speaks and writes some form of Cyrillic thanks to the great works of Saint Naum and the rest six of the Holy Apostles, that are nowadays little known in Russia and the rest of Slavonic world.


St. Seven Numbers and St. John Kukuzel. A fresco from 1744 from the main church of the monastery in Ardenitsa (present-day Albania), built on the foundations of the Holy Trinity Church, built with the patronage of St. Tsar Boris the Baptist. Written by the brothers Constantine and Anastas Zograf from Korca.

The names of the Seven Holy-equal apostles are  Saint Cyril and Methodius who created the Glagolitic script, and their five students Kliment, Naum, Gorazd, Sava and Angelariy.[ 3 ]. Another person we know of the of constellation of God enlightened apostle equal is Constantine of Preslav also considered a direct disciple of Methodius, the Church traditionally does not include him because he is not canonized (even though there is high probability he has been no less saint than the 7th). Saint Constantine of Preslav he is an author of the Alphabet prayer and multiple other Church books and works that are now completely destroyed and lost.

Saint Naum of Ohrid or Preslav himself was a medieval Bulgarian scientist (if we talk in terms of todays science), writer and saint. The Orthodox Church also venerates him as one of the Holy Septuagint translators as he used the famous Septuagint translation of the Bible as a specimen for his Cyrillic script translation.


Church sung chants on St Naum Feast

Troparion, voice 4

He left the world, became attached to Christ, crucified his flesh and lived spiritually, blessed Nahum.
You have endeavored to ascend in the way of the apostles, you have converted many, countless Moesians to the faith,
therefore, with your prayers, deliver us from temptations.

Kontakion sung, voice 3, similar to Virgo today

The honorable memory of your bright deeds, shining like a great sun for all,
enlightens those who sing to you, and casts out demons and all infirmities,
therefore, gathered with love, we truly praise her. 


Short Biography of Saint Naum

Biography Information about his life before arriving in Bulgaria is scarce.
According to one of his biographies, he was born in Moesia, "of noble parents", but despising wealth and nobility, he joined Cyril and Methodius [1] 

 According to the life of Cyril and Methodius by Clement of Ohrid, Nahum participated in their mission in Great Moravia, and in 868 was ordained in Rome. In 886, Nahum was expelled from Great Moravia after spending some time in prison for his resistance to the influence of the German clergy. He arrives in Bulgaria together with Kliment Ohridski, Sava, Angelariy and Gorazd. Monastery "St. Naum ”on Lake Ohrid Naum is one of the founders of the Preslav Literary School (originally in Pliska, that was a major Capital of Bulgaria at that time and first Capital of Bulgaria [2] ). In Pliska St. Nauh worked between 886 and 893 on copying important books of the bible and multiplying the still scarce Church books in Bulgarian. After Clement of Ohrid was appointed bishop of Drembica in 893, Nahum continued his work at the Ohrid Literary School. During this period he founded a monastery on Lake Ohrid in honour of Saint Archangel Michael (a very likely reference to Baptizmal name of Saint King Boris the Baptizer of Bulgaria who accepted the name Michael in his Baptism. The monastery in Ohrid, where his holy relics lays till this day in a small grave  is now named in honour.


Monastery of Saint Naum of Ohrid started by saint Naum

Even though the scarce information we have for the saint, the honour to Saint Naum over the centuries from the Slavonic Christiandome has been enormous and he has been especially invoked by people who suffer attacks by unclean spirits or are suffering long years sickness in heavy condition. In modern Theology he is also known under the name Saint Naum of Preslav-Ohrid a reference to the two major Bulgarian cities where he has done his spiritual labour in translating texts from Greek and perhaps Latin to the freshly invented Bulgarian alphabet recently reformed by his teacher Saint Kliment Ohridski who by himself has been a pupil of the Inventors of the Glagolic at that time Old-Bulgarian alphabet Saint Cyril and Saint Methodius.


Up view to Monastery of Saint Naum of Ohrid (the Church size was common in the time the aim of Building small Churches was to show the humbleness of Faith)

Venerable Nahum of Ohrid was the youngest of the disciples of the holy brothers Cyril and Methodius, in the town of Devol, Macedonia, instructed in the faith of Christ, fought there and died in 910.

Dormition of Saint Naum of Ohrid

His relics are a source of healing. Venerable Naum Ohridski died on December 23, 910, when his memory is celebrated even till today especially in Bulgaria and today's Macedonia which back in the day has been part of the Bulgaria (the far border of Bulgaria, historical Albania was just 300 meters from Ohrid's Saint Naum self-built Monastery).


Sea view to Monastery of Saint Naum Ohrid


Peacocks in the back yard of Saint Naum Church (peafowl has been common Christian symbol in the early centuries)

Since ancient times the Ohrid Archbishopric (which over the centuries has been usually identified with Bulgaria), closed as an independent in 1767 as desired by Turkish Sultan with the help of Ecumenical Patriarchate. In Bulgaria there is established June 20 as a day for a more solemn celebration of his memory.  [ 4 ]

Saint John Maksimovich (Bishop of Shanghai and San Francisco)

A curious and little known fact from the Life of almost contemporary 20 century saint John Maksimovitch (Saint John of Shanghai and San Francisco) is Saint John of Maksimovich discovered about Saint Naum's existence "by accidence" during his studies. Finding a relief and spiritual enlightment and support from the Saint he used to go to hospitals to pray for the sick holding an icon of saint Naum of Ohrid invoking his holy prayers, throughout his life he held a severe reverance for the saint, thanks to whose prayers Saint John Maksimovitch presented himself to Christ, passed to eternal life on his feast day 23st of December.


Saint Naum (right side) and Saint Clement of Ohrid

St. Naum Preslav-Ohrid remarkable Enlightener [ 5 ]

Author: Ivan Grudev


Brethren, let it not be without remembrance
Elder Nahum, this brother, comrade and
compassionate of Blessed Clement …
From the oldest biography of St. Naum, first quarter of the X century.

St. Naum Ohridski. Stamp of H. Zhefarovich, 1743. 1150 years have passed since the birth of Presbyter Nahum, the student, collaborator and successor of the great work of the equal apostles Cyril and Methodius, one of the most prominent figures of medieval Bulgaria.

The son of "his noble parents", Nahum grew up in Moesia (the biographer used the unofficial name of Bulgaria throughout the Middle Ages, and more likely – the medieval regional name of present-day Macedonia – Lower Moesia). There he joined Cyril and Methodius, "Who then walked all over the Bulgarian land, striving to convert the seduced to the Orthodox faith … To bring many to the Christian faith and enlighten them with the light of truth … translated the divine scripture, the old and the new, from the Hellenic (Greek) language to the simple Bulgarian language and invented letters for the Slavic language themselves "; or to Methodius during his reign as a Slavic principality in present-day Eastern Macedonia from approximately 837 to 847, or to Constantine-Cyril during his fateful mission among the Bulgarian Slavs of the Bregalnica valley (present-day northeastern Macedonia) from 855 to 859

The biographer's announcement that Nahum was the brother of Kliment Ohridski was accepted by most researchers in a spiritual sense – that the two were close associates in the great and long struggle for the establishment of the Slavic-Bulgarian education and literature. It seems the truth is different. A careful analysis of the facts that have come down to us cannot but lead to the conviction that perhaps Nahum and Clement were in fact brothers. The role of Nahum, the older brother, in relation to the ten-year-old and more talented Clement (born in the second half of the thirties of the ninth century), is strikingly reminiscent of the tender care and unwavering support of Methodius to Constantine. Cyril.

Both Nahum and Clement faithfully followed the Thessalonian brothers, providing them with the closest help and cooperation in their missions among their compatriots – the Bulgarian Slavs, the Khazars, Moravians and Pannonians, "Walking with them everywhere, even to ancient Rome."

After the death of Methodius on April 6, 885, Nahum was probably one of his closest students, who helped Clement to quickly write the Extensive Life of the immortal Slavic-Bulgarian first teacher, to raise him along with the previously written Extensive Life of Constantine-Cyril as a shield for the preservation of the works and covenants of the Holy Brothers among the Western Slavs. But their efforts are in vain. The united union of German feudal lords, the Catholic clergy and the traitors of the Moravian princely court subjected the work of Cyril and Methodius in Moravia and Pannonia to pogrom and destruction.

Clement's biographer reports that the persecuted students of Cyril and Methodius "longed for Bulgaria, thought about Bulgaria and hoped that Bulgaria was ready to give them peace." Such feelings and such aspirations could be felt only by people in trouble abroad, to their Fatherland, from which they once left with their favorite teachers around the world.

Unlike the Moravian and Pannonian students, who were thrown into prisons or sold into slavery, and some, such as Methodius' successor Gorazd and killed, Nahum, Clement and Angelarius, as Bulgarian subjects, were forcibly expelled from Moravia.

Reaching Belgrade with all their might, the three martyrs were received with great reverence by the Boritarkan (according to a later report, Prince Radislav), the Bulgarian military and civilian governor of the northwestern lands, as long-awaited guests. 

Saint King Equal-to-the-Apostles Boris-Mikhail from (852–889, Church feast 2 of May)

For a short time still holding a title Prince Boris-Mikhail enjoyed the dear guests in the capital Pliska, who brought there the light of the work of Cyril and Methodius, the most priceless treasure of the people and the state. The weary Angelarius died quickly, and after a short rest Clement took the road to the extreme southwest of the Bulgarian land, the territories most recently liberated from Byzantine rule, where the Greek cultural and religious influence of the great centers of Thessaloniki and Drach was almost irresistible. The highest state interests urgently demanded the creation of a hearth of Slavic-Bulgarian education and literature in order to save the Bulgarian language from the Greco-Byzantine aspirations. By order and with the generous help of Prince Boris-Mikhail, Clement established an educational and literary center in Devol (now a non-existent city in southern Albania).

Only Nahum remained in the northeastern Bulgarian lands. He was given a similar task. In order to avoid an undesirable complication of relations with the Greek clergy in Bulgaria and Byzantium behind them, again with the help of the wise ruler Nahum organized a Slavic-Bulgarian educational and literary center for the northeastern lands, but not in the capital Pliska, where the Greek Archbishop of Bulgaria, and in the nearby Slavic settlement of Preslav (and Clement chose for his activity not Lichnida, today Ohrid, the metropolitan center of the southwestern lands, but Devol, a city of the same diocese). The younger student of Metodiev, Konstantin Preslavski, reports that he was inspired by Nahum to write his Teaching Gospel. This announcement proves that the leader and organizer of the Preslav educational and literary center was Presbyter Naum.

After the brilliant research of our late scientist Prof. Ivan Galabov at the University of Salzburg, the use of non-scientific terms "Preslav Literary School" and "Ohrid Literary School" is no longer justified, as "school" primarily means individuality, originality, internal autonomous development. Prof. Iv. Galabov proved the very close cooperation between the artists from Devol-Ohrid and Preslav, in the undisputed championship and influence of Veliki Preslav, in which such giants worked as Presbyter Naum, Bishop Konstantin Preslavski, Presbyter John Exarch, blacksmith Dox (see Chernorizets Hnorizets Presbyter John, Presbyter Gregory the Monk, Blacksmith Tudor Doksov, Prince Simeon, etc., while the achievements of the Devolsko-Ohrid center are the work of only one Clement, although a giant of spirit and word. As far as Devol-Ohrid and Preslav flourished not only education and literature, but also fine and applied arts, architecture, crafts, etc., for which Prof. N. Mavrodinov proved their stylistic unity throughout the era of the First Bulgarian Kingdom, despite the insignificant local differences, the scientific concepts are "Devolsko-Ohrid Cultural Center" and "Preslav Cultural Center". 


The Grave of Saint Naum Ohrid (situated near the Northern Wall of the Church)

In his monastery on December 23, 910, the famous educator and benefactor of the Bulgarian people died, buried by his "brother, comrade and compassionate" Bishop Kliment Ohridski. His tomb is preserved to this day in a special chapel to the right of the altar of the monastery church.

Although the church has been rebuilt twice, the temple built by Nahum has remained the central building of the present one. This surviving church, with the tomb of Naum Preslav-Ohrid and its highly artistic frescoes from 1806, the work of painter Tarpo Konstantinov from Korca (probably Debar master, settled there, or a descendant of Debar settler), in which central place is occupied by the images of Prince Boris-Michael, the Holy Septuagint – Cyril, Methodius, Clement, Nahum, Gorazd, Sava and Angelarius, separately of Nahum, Clement and Prince John-Vladimir, is the most exciting pantheon of the First Bulgarian Kingdom and his Golden Age.

No, the presbyter Naum Preslavsko-Ohridski was not left without remembrance and praise. No Bulgarian has forgotten that he is one of the first masters who laid in Preslav and Ohrid the foundations on which Bulgarian culture is built from then until today. And forever.


Used Sources

1. ref (Duychev, Ivan. Extensive Greek biography in the service of Naum Ohridski, in: Duychev, Ivan. Studies on Medieval Bulgarian History and Culture, Sofia, 1981, p. 178. )



4. Extensive Orthodox Monthly lives, ed. Tavor and Lives of the Saints, Synodal Publishing House 1991

5. First publication on the Internet 




Linux: Howto Fix “N: Repository ‘ buster InRelease’ changed its ‘Version’ value from ‘10.9’ to ‘10.10’” error to resolve apt-get release update issue

Friday, August 13th, 2021

Linux's surprises and disorganization is continuously growing day by day and I start to realize it is becoming mostly impossible to support easily this piece of hackware bundled together.
Usually so far during the last 5 – 7 years, I rarely had any general issues with using:

 apt-get update && apt-get upgrade && apt-get dist-upgrade 

to raise a server's working stable Debian Linux version packages e.g. version X.Y to verzion X.Z (for example up the release from Debian Jessie from 8.1 to 8.2). 

Today I just tried to follow this well known and established procedure that, of course nowdays is better to be done with the newer "apt" command instead with the legacy "apt-get"
And the set of 


# apt-get update && apt-get upgrade && apt-get dist-upgrade


has triggered below shitty error:

root@zabbix:~# apt-get update && apt-get upgrade
Get:1 buster/updates InRelease [65.4 kB]
Get:2 buster InRelease [122 kB]
Get:3 buster/updates/non-free Sources [688 B]
Get:4 buster InRelease [7096 B]
Get:5 buster/updates/main Sources [198 kB]
Get:6 buster/updates/main amd64 Packages [300 kB]
Get:7 buster/updates/main Translation-en [157 kB]
Get:8 buster/updates/non-free amd64 Packages [556 B]
Get:9 buster/main Sources [7836 kB]
Get:10 buster/main Sources [1192 B]
Get:11 buster/main amd64 Packages [4785 B]
Get:12 buster/non-free Sources [85.7 kB]
Get:13 buster/contrib Sources [42.5 kB]
Get:14 buster/main amd64 Packages [7907 kB]
Get:15 buster/main Translation-en [5968 kB]
Get:16 buster/main amd64 Contents (deb) [37.3 MB]
Get:17 buster/contrib amd64 Packages [50.1 kB]
Get:18 buster/non-free amd64 Packages [87.7 kB]
Get:19 buster/non-free Translation-en [88.9 kB]
Get:20 buster/non-free amd64 Contents (deb) [861 kB]
Fetched 61.1 MB in 22s (2774 kB/s)
Reading package lists… Done
N: Repository ' buster InRelease' changed its 'Version' value from '10.9' to '10.10'

As I used to realize nowdays, as Linux started originally as 'Hackers' operating system, its legacy is just one big hack and everything from simple maintenance up to the higher and more sophisticated things requires a workaround 'hack''.


This time the hack to resolve error:

N: Repository ' buster InRelease' changed its 'Version' value from '10.9' to '10.10'

is up to running cmd:

debian-server:~# apt-get update –allow-releaseinfo-change
Поп:1 buster-backports InRelease
Поп:2 stable InRelease
Поп:3 stable/updates InRelease
Изт:5 buster InRelease [6837 B]
Изт:6 stretch InRelease [44,8 kB]
Изт:7 buster/main amd64 Packages [317 kB]
Игн:4  InRelease
Изт:8  Release [964 B]
Изт:9 buster/main i386 Packages [314 kB]
Изт:10  Release.gpg [481 B]
Грш:10  Release.gpg
  Следните подписи са невалидни: DDA2C105C4B73A6649AD2BBD47AE7F72479BC94B
Грш:11 generic InRelease
  403  Forbidden [IP: 443]
Четене на списъците с пакети… Готово
N: Repository ' buster InRelease' changed its 'Suite' value from '' to 'buster'
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error:  Release: 


Onwards to upgrade the system up to the latest .deb packages, as usual run:

# apt-get -y update && apt-get upgrade -y


and updates should be applied as usual with some prompts on whether you prefer to keep or replace existing service configuration and some information on some general changes that might affect your installed services. In a few minutes and few prompts hopefully your Debian OS should be up to the latest stable.

Saint Georgi of Sofia “the Newest” Bulgarian Confessor Christian saint martyred 1534 AD during reign of Turkish Sultan Selim in Medieval Serdika (Sofia)

Tuesday, June 1st, 2021


Troparion, voice 4
With a soul wounded by the love of your God, the wise George the Glorious, he preached to the ungodly, Christ God, trampled with his feeth, the Turkish heresy; and when he adorned himself with the crown of martyrdom, you ascended to the heavenly multitudes: ask Christ God to preserve your homeland, this city (Sofia) and the people who always worship your deeds.

On 26-th of May the Bulgarian Orthodox Church celebrates the memory of one of the great Bulgarian Martyr saints Saint Georgi the Newest.
С~тый Геԝ̀ргїй Софїѝскїй Новѣ̀йшїй) St. Georgi (The Bulgarian equivalent name of George) is one of the 3 saints holding the name Georgi which has confessed Christianity refused to accept islam and accepted Martyrdom for Christ in period of 1396 till year 1530 and one of the 9 famous Sofia city saints. Saint Georgi of Sofia the Newest was named after the highly venerated in Bulgarian just like in whole Christian world saint George.


St. Georgi was born in the city of Medieval Sofia (Sredetz), fortress of Serdika today’s Sofia in a family of Ivan and Maria – a wealthy and society recognized family of that time. He has born after a fervent and lengthly prayers of his parents who couldn’t have children for a long time and has been given a kid by the prayers of Saint Great Martyr George
It is important to say Georgi (the newest) celebrated on 26-th of May is a different saint from St. Georgi called “the new” whose memory in the Church is commemorated on 11-th of February.


Miracle making icon of saint Georgi Sofiyski (currently in the Church in yard of Alexandrovska Hospital Sofia)

The young Georgi quickly learned to write and read, a skills that only the most educated people usually coming from noble families could do. His favourite activity
in his free time when he was not in help of his parents was reading the Holy Scriptures.
He was grown by his parents in Christian goodness and fervency for the Christian faith.

Aged 25 he orphaned as his beloved father passed away to Christ. Georgi posessesed an extraordinary beauty, sharp mind and virtues, seeing the young man in his grief the local Turkish authorities tried as they usually do to attract the youngster to the islamic faith to make their way to interact with Georgi and do their business easier and most importantly have Georgi in their auhotirities congregation consisting only of people belonging to the islam as it was up to the Ottoman Turkish consistution law of the day.

To attract Georgi, turks first tried with hypocritical kindness and a care for the young to help him raise in the power of authorities of the city, not succeeding with that they have, they have forcefully wrapper the Muslim turban on his head and proclaimed him officially Muslim. Feeling offended by the ungodly deed of this enemies of Christ, immediately the saint throw the imposed turban on the ground and trampled on it.
The enraged muslim crowd seing his public offence for the prophet Muhammed handed him over to the Qadi in the court.

Neither the seductive promises of high office nor the cruel tortures could break the unshakable firmness of his Christian faith. The judge ordered that his body be cut into strips from head to toe and that the wounds received be scorched with dirty candles, which made the martyr’s body so hot that his face could not be seen. But all efforts were in vain.

The final verdict of the judge followed – Georgi to be hanged on the main barn in the city of Sofia, where there was a furnace for melting iron and copper ore. The execution command also stated that his body should remain on the gallows for three days in order to begin to decay, so that the faith of the Christians in the incorruptible relics of the saints and in the resurrection of the dead to be refuted and hence disgrace christianity. However, exhausted from his suffering mrtr. Georgi died at the hands of the executioners before they managed to hang him. To fulfill the command turks, anyhow hung him on a rope to show the sentence has been successfully carried out.

For three days the body hung on the gallows without any sign of decomposition, and on the contrary, an unusual fragrance of the holy relics of the martyr wafted through the barn. His mother sat under the gallows and grieving his beloved son hugged her son’s legs, staying next three three days to her son. The hanging took place on May 26, 1530 (according to other document sources in 1534). Thus on 26th of may the Church set a service in memoriam.


5-th Century Church of Rotonda St. George Centre of Sofia


Saint Georgi Sofiyski / Saint George of Sofia the Newest grave near Rotonda Church Saint George in City Center of Sofia, Bulgari

After the expiration of the sentence, the kadi handed over the body of the martyr to be buried in a Christian way, and the burial was solemnly performed by the then Metropolitan of Sofia Jeremiah in the church “St. the great martyr George the Victorious ”. Now these relics are in obscurity. The mother of the martyr died on the 40th day of George’s death and was buried at her son’s feet.

These events took place during the reign of Sultan Suleiman I Kanuni (the Legislator) also known as Suleiman the Magnificent. This “Golden Age” for the Ottoman Empire was a time of unheard of atrocities against Christians in the territory of the empire and very difficult times for the Bulgarian people. The reign of Suleiman I and his father Selim I was a time of obscurantism and severe persecution of the Christian population, a time during which many Christian new martyrs on Balkans had the courage to defend their faith.


The capture, trial and torture of St. George of Sofia The latest took place near the then Sofia. Today the place is located in the yard of the famous Alexandrovska Hospital which was a King’s hospital during the times of Kingdom of Bulgaria after liberation took place from the Turks in 1878 y.. The exact location where martyrdom occured is between street St. Georgi Sofiyski ”and“ Pencho Slaveykov ”Blvd.

There was a large stone cross with an inscription on the site, which a few years after 1944, due to the risk of being destroyed, was collected by Sofia priests and is still preserved in the altar of the church “St. Georgi Pobedonosets ”on Blvd. Partriarch Euthymius”. Until the 1940s, a liturgical procession was held from the place of death of the saint to the Rotunda on May 26.
Nowadays happily, the old Lithia tradition is being renewed and a small Lithia is conducted by Bulgarian Orthodox Christian clergy and layman.

In the garden next to the building of the Second Surgical Clinic there was a stone cross, which indicated the place and history of the martyrdom of the saint, and today a temple was built in honor of the saint.

source: Lives of the Saints. Synodal Publishing House, Sofia, 1991, edited by Parthenius, Bishop of Lefkada and Archimandrite Dr. Athanasius (Bonchev).



Install certbot on Debian, Ubuntu, CentOS, Fedora Linux 10 / Generate and use Apache / Nginx SSL Letsencrypt certificates

Monday, December 21st, 2020

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Internet Security Research Group (ISRG). ISRG group gave initiative with the goal to "encrypt the internet", i.e. offer free alternative to the overpriced domani registrer sold certificates with the goal to make more people offer SSL / TSL Free secured connection line on their websites. 
ISRG group supported Letsencrypt non-profit certificate authority actrively by Internet industry standard giants such as Mozilla, Cisco, EFF (Electronic Frontier Foundation),  Facebook, Google Chrome, Amazon AWS, OVH Cloud, Redhat, VMWare, Github and many many of the leading companies in IT.

Letsencrpyt is aimed at automating the process designed to overcome manual creation, validation, signing, installation, and renewal of certificates for secure websites. I.e. you don't have to manually write on console complicated openssl command lines with passing on Certificate CSR /  KEY / PEM files etc and generate Self-Signed Untrusted Authority Certificates (noted in my previous article How to generate Self-Signed SSL Certificates with openssl or use similar process to pay money generate secret key and submit the key to third party authority through a their website webadmin  interface in order to Generate SSL brought by Godaddy or Other Certificate Authority.

But of course as you can guess there are downsides as you submit your private key automatically via letsencrypt set of SSL certificate automation domain scripts to a third party Certificate Authority which is at A security intrusion in their private key store servers might mean a catastrophy for your data as malicious stealer might be able to decrypt your data with some additional effort and see in plain text what is talking to your Apache / Nginx or Mail Server nevertheless the cert. Hence for a high standards such as PCI environments Letsencrypt as well as for the paranoid security freak admins,  who don't trust the mainstream letsencrypt is definitely not a choice. Anyways for most small and midsized businesses who doesn't hold too much of a top secret data and want a moderate level of security Letsencrypt is a great opportunity to try. But enough talk, lets get down to business.

How to install and use certbot on Debian GNU / Linux 10 Buster?
Certbot is not available from the Debian software repositories by default, but it’s possible to configure the buster-backports repository in your /etc/apt/sources.list file to allow you to install a backport of the Certbot software with APT tool.

1. Install certbot on Debian / Ubuntu Linux


root@webserver:/etc/apt# tail -n 1 /etc/apt/sources.list
deb buster-backports main

If not there append the repositories to file:


  • Install certbot-nginx certbot-apache deb packages

root@webserver:/ # echo 'deb buster-backports main' >> /etc/apt/sources.list


  • Install certbot-nginx certbot-apache deb packages

root@webserver:/ # apt update
root@webserver:/ # apt install certbot python-certbot-nginx python3-certbot-apache python-certbot-nginx-doc

This will install the /usr/bin/certbot python executable script which is used to register / renew / revoke / delete your domains certificates.

2. Install letsencrypt certbot client on CentOS / RHEL / Fedora and other Linux Distributions


For RPM based distributions and other Linux distributions you will have to install snap package (if not already installed) and use snap command :



[root@centos ~ :] # yum install snapd
systemctl enable –now snapd.socket

To enable classic snap support, enter the following to create a symbolic link between

[root@centos ~ :] # ln -s /var/lib/snapd/snap /snap

snap command lets you install, configure, refresh and remove snaps.  Snaps are packages that work across many different Linux distributions, enabling secure delivery and operation of the latest apps and utilities.

[root@centos ~ :] # snap install core; sudo snap refresh core

Logout from console or Xsession to make the snap update its $PATH definitions.

Then use snap universal distro certbot classic package

 [root@centos ~ :] # snap install –classic certbot
[root@centos ~ :] # ln -s /snap/bin/certbot /usr/bin/certbot


If you're having an XOrg server access on the RHEL / CentOS via Xming or other type of Xemulator you might check out also the snap-store as it contains a multitude of packages installable which are not usually available in RPM distros.

 [root@centos ~ :] # snap install snap-store


snap-store is a powerful and via it you can install many non easily installable stuff on Linux such as eclipse famous development IDE, notepad++ , Discord, the so favourite for the Quality Assurance guy Protocol tester Postman etc.

  • Installing certbot to any distribution via script

Another often preferred solution to Universally deploy  and upgrade an existing LetsEncrypt program to any Linux distribution (e.g. RHEL / CentOS / Fedora etc.) is the script. To install acme you have to clone the repository and run the script with –install

P.S. If you don't have git installed yet do

root@webserver:/ # apt-get install –yes git

and then the usual git clone to fetch it at your side

# cd /root
# git clone
Cloning into ''…
remote: Enumerating objects: 71, done.
remote: Counting objects: 100% (71/71), done.
remote: Compressing objects: 100% (53/53), done.
remote: Total 12475 (delta 39), reused 38 (delta 18), pack-reused 12404
Receiving objects: 100% (12475/12475), 4.79 MiB | 6.66 MiB/s, done.
Resolving deltas: 100% (7444/7444), done.

# sh –install

To later upgrade to latest you can do

# sh –upgrade

In order to renew a concrete existing letsencrypt certificiate

# sh –renew

To renew all certificates using script

# ./ –renew-all


3. Generate Apache or NGINX Free SSL / TLS Certificate with certbot tool

Now lets generate a certificate for a domain running on Apache Webserver with a Website WebRoot directory /home/phpdev/public/www


root@webserver:/ # certbot –apache –webroot -w /home/phpdev/public/www/ -d -d

root@webserver:/ # certbot certonly –webroot -w /home/phpdev/public/www/ -d -d

As you see all the domains for which you will need to generate are passed on with -d option.

Once certificates are properly generated you can test it in a browser and once you're sure they work as expected usually you can sleep safe for the next 3 months ( 90 days) which is the default for TSL / SSL Letsencrypt certificates the reason behind of course is security.


4. Enable freshly generated letsencrypt SSL certificate in Nginx VirtualHost config

Go to your nginx VirtualHost configuration (i.e. /etc/nginx/sites-enabled/ ) and inside chunk of config add after location { … } – 443 TCP Port SSL listener (as in shown in bolded configuration)

server {

   location ~ \.php$ {
      include /etc/nginx/fastcgi_params;
##      fastcgi_pass;
      fastcgi_pass unix:/run/php/php7.3-fpm.sock;
      fastcgi_index index.php;
      fastcgi_param SCRIPT_FILENAME /usr/share/phpmyadmin$fastcgi_script_name;



    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot


5. Enable new generated letsencrypt SSL certificate in Apache VirtualHost

In /etc/apache2/{sites-available,sites-enabled}/ you should have as a minimum a configuration setup like below:


NameVirtualHost *:443 <VirtualHost>
    HostnameLookups off
    DocumentRoot /var/www
    DirectoryIndex index.html index.htm index.php index.html.var



CheckSpelling on
SSLEngine on

    <Directory />
        Options FollowSymLinks
        AllowOverride All
        ##Order allow,deny
        ##allow from all
        Require all granted
    <Directory /var/www>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
##      Order allow,deny
##      allow from all
Require all granted

Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateFile /etc/letsencrypt/live/
SSLCertificateKeyFile /etc/letsencrypt/live/


6. Simulate a certificate regenerate with –dry-run

Soon before the 90 days period expiry approaches, it is a good idea to test how all installed Nginx webserver certficiates will be renewed and whether any issues are expected this can be done with the –dry-run option.

root@webserver:/ # certbot renew –dry-run


– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
** DRY RUN: simulating 'certbot renew' close to cert expiry
**          (The test certificates below have not been saved.)

Congratulations, all renewals succeeded. The following certs have been renewed:
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
  /etc/letsencrypt/live/ (success)
** DRY RUN: simulating 'certbot renew' close to cert expiry
**          (The test certificates above have not been saved.)
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –


7. Renew a certificate from a multiple installed certificate list

In some time when you need to renew letsencrypt domain certificates you can list them and choose manually which one you want to renew.

root@webserver:/ # certbot –force-renewal
Saving debug log to /var/log/letsencrypt/letsencrypt.log

How would you like to authenticate and install certificates?
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
1: Apache Web Server plugin (apache)
2: Nginx Web Server plugin (nginx)
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Plugins selected: Authenticator nginx, Installer nginx

Which names would you like to activate HTTPS for?
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel): 3
Renewing an existing certificate
Deploying Certificate to VirtualHost /etc/nginx/sites-enabled/

Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
1: No redirect – Make no further changes to the webserver configuration.
2: Redirect – Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Redirecting all traffic on port 80 to ssl in /etc/nginx/sites-enabled/

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Your existing certificate has been successfully renewed, and the new certificate
has been installed.

The new certificate covers the following domains:

You should test your configuration at:
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

 – Congratulations! Your certificate and chain have been saved at:

   Your key file has been saved at:
   Your cert will expire on 2021-03-21. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot again
   with the "certonly" option. To non-interactively renew *all* of
   your certificates, run "certbot renew"
 – If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:
   Donating to EFF:          


8. Renew all present SSL certificates

root@webserver:/ # certbot renew

Processing /etc/letsencrypt/renewal/
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Cert not yet due for renewal


– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

The following certs are not due for renewal yet:
  /etc/letsencrypt/live/ expires on 2021-03-01 (skipped)
  /etc/letsencrypt/live/ expires on 2021-02-28 (skipped)
  /etc/letsencrypt/live/ expires on 2021-02-28 (skipped)
  /etc/letsencrypt/live/ expires on 2021-03-01 (skipped)
  /etc/letsencrypt/live/ expires on 2021-02-25 (skipped)
  /etc/letsencrypt/live/ expires on 2021-03-21 (skipped)
  /etc/letsencrypt/live/ expires on 2021-02-28 (skipped)
  /etc/letsencrypt/live/ expires on 2021-03-01 (skipped)
No renewals were attempted.
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –



9. Renew all existing server certificates from a cron job

The certbot package will install a script under /etc/cron.d/certbot to be run that will attempt every 12 hours however from my experience
often this script is not going to work, the script looks similar to below:

# Upgrade all existing SSL certbot machine certificates


0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(43200))' && certbot -q renew

Another approach to renew all installed certificates if you want to have a specific options and keep log of what happened is using a tiny shell script like this:


10. Auto renew installed SSL / TSL Certbot certificates with a bash loop over all present certificates

# update SSL certificates
# prints from 1 to 104 (according to each certbot generated certificate and triggers rewew and logs what happened to log file
# an ugly hack for certbot certificate renew
for i in $(seq 1 104); do echo "Updating $i SSL Cert" | tee -a /root/certificate-update.log; yes "$i" | certbot –force-renewal | tee -a /root/certificate-update.log 2>&1; sleep 5; done

Note: The seq 1 104 is the range depends on the count of installed SSL certificates you have installed on the machine, that can be seen and set the proper value according to your case when you run one time certbot –force-renewal.

Deny DHCP Address by MAC on Linux

Thursday, October 8th, 2020

Deny DHCP addresses by MAC ignore MAC to not be DHCPD leased on GNU / Linux howto

I have not blogged for a long time due to being on a few weeks vacation and being in home with a small cute baby. However as a hardcore and a bit of dumb System administrator, I have spend some of my vacation and   worked on bringing up the the and the other Websites hosted as a high availvailability ones living on a 2 Webservers running on a Master to Master MySQL Replication backend database, this is oll hosted on  servers, set to run as a round robin DNS hosts on 2 servers one old Lenove ThinkCentre Edge71 as well as a brand new real Lenovo server Lenovo ThinkServer SD350 with 24 CPUs and a 32 GB of RAM
To assure Internet Connectivity is having a good degree of connectivity and ensure websites hosted on both machines is not going to die if one of the 2 pair configured Fiber Optics Internet Providers Bergon.NET has some Issues, I've rented another Internet Provider Line is set bought from the VIVACOM Mobile Fiber Internet provider – that is a 1 Gigabit Fiber Optics Line.
Next to that to guarantee there is no Database, Webserver, MailServer, Memcached and other running services did not hit downtimes due to Electricity power outage, two Powerful Uninterruptable Power Supplies (UPS)  FPS Fortron devices are connected to the servers each of which that could keep the machine and the connected switches and Servers for up to 1 Hour.

The machines are configured to use dhcpd to distributed IP addresses and the Main Node is set to distribute IPs, however as there is a local LAN network with more of a personal Work PCs, Wireless Devices and Testing Computers and few Virtual machines in the Network and the IPs are being distributed in a consequential manner via a ISC DHCP server.

As always to make everything work properly hence, I had again some a bit weird non-standard requirement to make some of the computers within the Network with Static IP addresses and the others to have their IPs received via the DHCP (Dynamic Host Configuration Protocol) and add some filter for some of the Machine MAC Addresses which are configured to have a static IP addresses to prevent the DHCP (daemon) server to automatically reassign IPs to this machines.

After a bit of googling and pondering I've done it and some of the machines, therefore to save others the efforts to look around How to set Certain Computers / Servers Network Card MAC (Interfaces) MAC Addresses  configured on the LAN network to use Static IPs and instruct the DHCP server to ingnore any broadcast IP addresses leases – if they're to be destined to a set of IGNORED MAcs, I came up with this small article.

Here is the DHCP server /etc/dhcpd/dhcpd.conf from my Debian GNU / Linux (Buster) 10.4


option domain-name "pcfreak.lan";
option domain-name-servers,,,;
max-lease-time 891200;
class "black-hole" {
    match substring (hardware, 1, 6);
    ignore booting;
subclass "black-hole" 18:45:91:c3:d9:00;
subclass "black-hole" 70:e2:81:13:44:11;
subclass "black-hole" 70:e2:81:13:44:12;
subclass "black-hole" 00:16:3f:53:5d:11;
subclass "black-hole" 18:45:9b:c6:d9:00;
subclass "black-hole" 16:45:93:c3:d9:09;
subclass "black-hole" 16:45:94:c3:d9:0d;/etc/dhcpd/dhcpd.conf
subclass "black-hole" 60:67:21:3c:20:ec;
subclass "black-hole" 60:67:20:5c:20:ed;
subclass "black-hole" 00:16:3e:0f:48:04;
subclass "black-hole" 00:16:3e:3a:f4:fc;
subclass "black-hole" 50:d4:f5:13:e8:ba;
subclass "black-hole" 50:d4:f5:13:e8:bb;
subnet netmask {
        option routers        ;
        option subnet-mask    ;
host think-server {
        hardware ethernet 70:e2:85:13:44:12;
default-lease-time 691200;
max-lease-time 891200;
log-facility local7;

To spend you copy paste efforts a file with Deny DHCP Address by Mac Linux configuration is here
Of course I have dumped the MAC Addresses to omit a data leaking but I guess the idea behind the MAC ADDR ignore is quite clear

The main configuration doing the trick to ignore a certain MAC ALenovo ThinkServer SD350ddresses that are reachable on the Connected hardware switch on the device is like so:

class "black-hole" {
    match substring (hardware, 1, 6);
    ignore booting;
subclass "black-hole" 18:45:91:c3:d9:00;

The Deny DHCP Address by MAC is described on distribution lists here but it seems the documentation on the topic on how to Deny / IGNORE DHCP Addresses by MAC Address on Linux has been quite obscure and limited online.

As you can see in above config the time via which an IP is freed up and a new IP lease is done from the server is severely maximized as often DHCP servers do use a max-lease-time like 1 hour (3600) seconds:, the reason for increasing the lease time to be to like 10 days time is that the IPs in my network change very rarely so it is a waste of CPU cycles to do a frequent lease.

default-lease-time 691200;
max-lease-time 891200;

As you see to Guarantee resolving works always as expected I have configured – Google Public DNS and OpenDNS IPs

option domain-name-servers,,,;

One hint to make is, after setting up all my desired config in the standard config location /etc/dhcp/dhcpd.conf it is always good idea to test configuration before reloading the running dhcpd process.


root@pcfreak: ~# /usr/sbin/dhcpd -t
Internet Systems Consortium DHCP Server 4.4.1
Copyright 2004-2018 Internet Systems Consortium.
All rights reserved.
For info, please visit
Config file: /etc/dhcp/dhcpd.conf
Database file: /va/home/hipo/infor/lib/dhcp/dhcpd.leases
PID file: /var/run/

That's all folks with this sample config the IPs under subclass "black-hole", which are a local LAN Static IP Addresses will never be offered leasess anymore from the ISC DHCP.
Hope this stuff helps someone, enjoy and in case if you need a colocation of a server or a website hosting for a really cheap price on this new set High Availlability up described machines open an inquiry on


Upgrade Debian Linux 9 to 10 Stretch to Buster and Disable graphical service load boot on Debian 10 Linux / Debian Buster is out

Tuesday, July 9th, 2019


I've just took a time to upgrade my Debian 9 Stretch Linux to Debian Buster on my old school Laptop (that turned 11 years old) Lenovo Thinkpad R61 . The upgrade went more or less without severe issues except few things.

The overall procedure followed is described n a few websites out there already and comes up to;


0. Set the proper repository location in /etc/apt/sources.list

Before update the sources.list used are:

deb [arch=amd64,i386] buster main contrib non-free
deb-src [arch=amd64,i386] buster main contrib non-free


deb [arch=amd64,i386] buster/updates main contrib non-free
deb-src [arch=amd64,i386] buster/updates main contrib non-free

deb [arch=amd64,i386] buster-updates main contrib non-free
deb-src [arch=amd64,i386] buster-updates main contrib non-free

deb buster-backports main

For people that had stretch defined in /etc/apt/sources.list you should change them to buster or stable, easiest and quickest way to omit editting with vim / nano etc. is run as root or via sudo:

sed -i 's/stretch/buster/g' /etc/apt/sources.list
sed -i 's/stretch/buster/g' /etc/apt/sources.list.d/*.list

The minimum of config in sources.list after the modification should be

deb buster main
deb buster-updates main
deb buster/updates main

Or if you want to always be with latest stable packages (which is my practice for notebooks):

deb stable main
deb stable-updates main
deb stable/updates main


1. Getting list of hold packages if such exist and unholding them, e.g.


apt-mark showhold

Same could also be done via dpkg

dpkg –get-selections | grep hold

To unhold a package if such is found:

echo "package_name install"|sudo dpkg –set-selections

For those who don't know what hold package is this is usually package you want to keep at certain version all the time even though after running apt-get upgrade to get the latest package versions.

2. Use df -h and assure you have at least 5 – 10 GB free space on root directory / before proceed

df -h /

3. Update packages list to set new set repos as default

apt update


4. apt upgrade

apt upgrade

Here some 10 – 15 times you have to confirm what you want to do with configuration that has changed if you're unsure about the config (and it is not critical service) you're aware as such as Apache / MySQL / SMTP etc. it is best to install the latest maintainer version.

Hopefully here you will not get fatal errors that will interrupt it.

P.S. It is best to run apt-update either in VTTY (Virtual console session) with screen or tmux or via a physical tty (if this is not a remote server) as during the updates your GUI access to the gnome-terminal or konsole / xterm whatever console used might get cut. Thus it is best to do it with command:

screen apt upgrade


5. Run dist-upgrade to finalize the upgrade from Stertch to Buster


Once all is completed of the new installed packages, you will need to finally do, once again it is best to run via screen, if you don't have installed screen install it:


if [ $(which screen) ]; then echo 'Installed'; else apt-get install –yes screen ; fi

screen apt dist-upgrade

Here once again you should set whether old configuration to some e services has to stay or the new Debian maintainer package shipped one will overwrite the old and locally modified (due to some reason), here do wisely whatever you will otherwise some configured services might not boot as expected on next boot.


6. What if you get packages failed on update

If you get a certain package failed to configure after installed due to some reason, if it is a systemd service use:


journalctl -xe |head -n 50

or fully observer output of journalctl -xe and decide on yourself.

In most cases

dpkg-reconfigure failed-package-name

should do the trick or at least give you more hints on how to solve it.


Also if a package seems to be in inconsistent or broken state after upgrade  and simple dpkg-reconfigure doesn't help, a good command
that can help you is


dpkg-reconfigure -f package_name


or you can try to workaround a failed package setup with:

dpkg –configure -a

If dpkg-reconfigure doesn't help either as I experienced in prior of Debian from Debian 6 -> 7 an Debian 7 ->8 updates on some Computers, then a very useful thing to try is:

apt-get update –fix-missing 

apt-get install -f

At certain cases the only work around to be able to complete the package upgrade is to to remove the package with apt remove but due to config errors even that is not possible to work around this as final resort run:

dpkg –remove –force-remove-reinstreq


7. Clean up ununeeded packages


Some packages are left over due to package dependencies from Stretch and not needed in buster anymore to remove them.

apt autoremove


8. Reboot system once all upgrade is over




9. Verify your just upgraded Debian is in a good state


root@noah:~# uname -a;
Linux noah 4.19.0-5-rt-amd64 #1 SMP PREEMPT RT Debian 4.19.37-5 (2019-06-19) x86_64 GNU/Linux


root@noah:~# cat /etc/
Debian GNU/Linux 10


root@noah:~# lsb_release -a
No LSB modules are available.
Distributor ID:    Debian
Description:    Debian GNU/Linux 10 (buster)
Release:    10
Codename:    buster


root@noah:~# hostnamectl
   Static hostname: noah
         Icon name: computer-laptop
           Chassis: laptop
        Machine ID: 4759d9c2f20265938692146351a07929
           Boot ID: 256eb64ffa5e413b8f959f7ef43d919f
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.0-5-rt-amd64
      Architecture: x86-64


10. Remove annoying picture short animation with debian logo looping



By default Debian 10 boots up with annoying screen hiding all the status of loaded services state .e.g. you cannot see the services that shows in [ FAILED ] state and  which do show as [ OK ] to revert back the old behavior I'm used to for historical reasons and as it shows a lot of good Boot time debugging info, in previous Debian distributions this was possible  by setting the right configuration options in /etc/default/grub

which so far in my config was like so

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash scsi_mod.use_blk_mq=y dm_mod.use_blk_mq=y zswap.enabled=1 text"

Note that zswap.enabled=1 passed option is because my notebook is pretty old machine from 2008 with 4GB of memory and zswap does accelerate performance when working with swap – especially helpful on Older PCs for more you can read more about zswap on ArchLinux wiki
After modifying this configuration to load the new config into grub the cmd is:


As this was not working and tried number of reboots finally I found that annoying animated gif like picture shown up is caused by plymouth below is excerpts from Plymouth's manual page:

       "The plymouth sends commands to a running plymouthd. This is used during the boot process to control the display of the graphical boot splash."

Plymouth has a set of themes one can set:


# plymouth-set-default-theme -l


I tried to change that theme to make the boot process as text boot as I'm used to historically with cmd:

update-alternatives –config text.plymouth

As after reboot I hoped the PC will start booting in text but this does not happened so the final fix to turn back to textmode service boot was to completely remove plymouth

apt-get remove –yes plymouth

How to install KVM Kernel-based Virtual Machine Virtualization on Linux

Sunday, October 14th, 2018


If you want to run multiple virtual machines on GNU / Linux server or your Linux powered Desktop you have the possibility to use a couple of Virtual Machines just to name a few VirtualBox and VMWare are the option the native way to do it is using the Linux kernel via a loadable kernel module called KVM (Kernel-based Virtual Machine).
Though Oracle's Virtualbox generally works and you could add new test beds virtual machines (install multiple Linux / *BSD OS) it is not fully Free Software and not even fully open source licensed, VMWare even though superior as a Virtualization product is proprietary and its application costs a lot of money which not each develpoper or small / mid-sized company could afford.

Once the kvm.ko module is loaded your Linux kernel turns into a full-featured Virtual Machine Hypervisor.
Starting with Linux kernel 2.6.X the KVM Hypervisor is available and easy to install virtually all modern Linux distributions Redhat / CentOS Debian / Ubuntu etc. support it and its up to running few commands to install and start using the Power of Kernel embedded Virtualization.

KVM could be used to run in parallel multiple Operating Systems such as Windows / Linux / FreeBSD and others of BSDs family,  each running under a separate virtual machine with its private dedicated (isolated), disc, graphic card, network card etc.

To start up I assume you have already installed some kind of Linux distribution either locally or on a remote dedicated server.

1. Installing KVM on Debian GNU / Linux / Ubuntu / Mint and other deb based distros


Using APT tool install below packages:


root@jeremiah:~# apt install –yes qemu-kvm libvirt-clients libvirt-daemon-system bridge-utils libguestfs-tools genisoimage virtinst libosinfo-bin


2. Installing virt-manager GUI to manage Virtual servers


root@jeremiah:~# apt-cache show virt-manager|grep -i desc -A 1
Description-en: desktop application for managing virtual machines
 It presents a summary view of running domains and their live performance &

Description-md5: 9f7f584744b77cdacc2291f2a8ac220e


root@jeremiah:~# apt install –yes virt-manager






3. Configure bridged networking to allow access to newly configured VMs

Bridging has to be added via /etc/network/interfaces therefore it is a good idea to create a backup of it before modifying:


# cp -rpf /etc/network/interfaces /etc/network/interfaces.bakup-$(echo $(date '+%Y-%m-%d-%H'))


# vim /etc/network/interfaces

auto br0
 iface br0 inet static
         # set static route for LAN
      post-up route add -net netmask gw
      post-up route add -net netmask gw
         bridge_ports eth0
         bridge_stp off
         bridge_fd 0
         bridge_maxwait 0
 # br1 setup with static wan IPv4 with ISP router as a default gateway
 auto br1
 iface br1 inet static
         bridge_ports eth1
         bridge_stp off
         bridge_fd 0
         bridge_maxwait 0


Once file is saved in vim editor restart the networking.


# systemctl restart network.manager


To verify whether the bridge has been succesfully upped.


root@jeremiah:/home/hipo/kvm# brctl show
bridge name    bridge id        STP enabled    interfaces
virbr0        8000.525400cb1cd1    yes        virbr0-nic


4. List all installable Virtual OS images

root@jeremiah:/home/hipo/kvm# virt-builder -list
centos-6                 x86_64     CentOS 6.6
centos-7.0               x86_64     CentOS 7.0
centos-7.1               x86_64     CentOS 7.1
centos-7.2               aarch64    CentOS 7.2 (aarch64)
centos-7.2               x86_64     CentOS 7.2
centos-7.3               x86_64     CentOS 7.3
centos-7.4               x86_64     CentOS 7.4
centos-7.5               x86_64     CentOS 7.5
cirros-0.3.1             x86_64     CirrOS 0.3.1
cirros-0.3.5             x86_64     CirrOS 0.3.5
debian-6                 x86_64     Debian 6 (Squeeze)
debian-7                 sparc64    Debian 7 (Wheezy) (sparc64)
debian-7                 x86_64     Debian 7 (wheezy)
debian-8                 x86_64     Debian 8 (jessie)
debian-9                 x86_64     Debian 9 (stretch)
fedora-18                x86_64     Fedora® 18
fedora-19                x86_64     Fedora® 19
fedora-20                x86_64     Fedora® 20
fedora-21                aarch64    Fedora® 21 Server (aarch64)
fedora-21                armv7l     Fedora® 21 Server (armv7l)
fedora-21                ppc64      Fedora® 21 Server (ppc64)
fedora-21                ppc64le    Fedora® 21 Server (ppc64le)
fedora-21                x86_64     Fedora® 21 Server
fedora-22                aarch64    Fedora® 22 Server (aarch64)
fedora-22                armv7l     Fedora® 22 Server (armv7l)
fedora-22                i686       Fedora® 22 Server (i686)
fedora-22                x86_64     Fedora® 22 Server
fedora-23                aarch64    Fedora® 23 Server (aarch64)
fedora-23                armv7l     Fedora® 23 Server (armv7l)
fedora-23                i686       Fedora® 23 Server (i686)
fedora-23                ppc64      Fedora® 23 Server (ppc64)
fedora-23                ppc64le    Fedora® 23 Server (ppc64le)
fedora-23                x86_64     Fedora® 23 Server
fedora-24                aarch64    Fedora® 24 Server (aarch64)
fedora-24                armv7l     Fedora® 24 Server (armv7l)
fedora-24                i686       Fedora® 24 Server (i686)
fedora-24                x86_64     Fedora® 24 Server
fedora-25                aarch64    Fedora® 25 Server (aarch64)
fedora-25                armv7l     Fedora® 25 Server (armv7l)
fedora-25                i686       Fedora® 25 Server (i686)
fedora-25                ppc64      Fedora® 25 Server (ppc64)
fedora-25                ppc64le    Fedora® 25 Server (ppc64le)
fedora-25                x86_64     Fedora® 25 Server
fedora-26                aarch64    Fedora® 26 Server (aarch64)
fedora-26                armv7l     Fedora® 26 Server (armv7l)
fedora-26                i686       Fedora® 26 Server (i686)
fedora-26                ppc64      Fedora® 26 Server (ppc64)
fedora-26                ppc64le    Fedora® 26 Server (ppc64le)
fedora-26                x86_64     Fedora® 26 Server
fedora-27                aarch64    Fedora® 27 Server (aarch64)
fedora-27                armv7l     Fedora® 27 Server (armv7l)
fedora-27                i686       Fedora® 27 Server (i686)
fedora-27                ppc64      Fedora® 27 Server (ppc64)
fedora-27                ppc64le    Fedora® 27 Server (ppc64le)
fedora-27                x86_64     Fedora® 27 Server
fedora-28                i686       Fedora® 28 Server (i686)
fedora-28                x86_64     Fedora® 28 Server
freebsd-11.1             x86_64     FreeBSD 11.1
scientificlinux-6        x86_64     Scientific Linux 6.5
ubuntu-10.04             x86_64     Ubuntu 10.04 (Lucid)
ubuntu-12.04             x86_64     Ubuntu 12.04 (Precise)
ubuntu-14.04             x86_64     Ubuntu 14.04 (Trusty)
ubuntu-16.04             x86_64     Ubuntu 16.04 (Xenial)
ubuntu-18.04             x86_64     Ubuntu 18.04 (bionic)
opensuse-13.1            x86_64     openSUSE 13.1
opensuse-13.2            x86_64     openSUSE 13.2
opensuse-42.1            x86_64     openSUSE Leap 42.1
opensuse-tumbleweed      x86_64     openSUSE Tumbleweed

5. Create Virtual Machine OS-es from scratch with virt-builder

Below we'll create two images one for Fedora 28 and 1 for Debian 9 using the virt-builder (a tool to build virtual images quickly), the images that could be used are shown through below virt-builder –list command.

# iso='fedora-28';
# iso1='debian-9';


# sudo virt-builder $iso \
     –size=10G \
     –format qcow2 -o /var/lib/libvirt/images/$iso-vm1.qcow2 \
     –hostname $iso-vm1 \
     –network \
     –timezone Europe/Sofia


[   3.3] Downloading:
[   5.2] Planning how to build this image
[   5.2] Uncompressing
[  20.8] Resizing (using virt-resize) to expand the disk to 10.0G
[  50.8] Opening the new disk
[  53.7] Setting a random seed
[  53.7] Setting the hostname: fedora-28-vm1
[  53.7] Setting the timezone: Europe/Sofia
[  53.7] Setting passwords
virt-builder: Setting random password of root to YMTkxaJIkEU24Ytf

[  54.7] Finishing off
                   Output file: /var/lib/libvirt/images/fedora-28-vm1.qcow2
                   Output size: 10.0G
                 Output format: qcow2
            Total usable space: 9.3G
                    Free space: 8.2G (87%)


# sudo virt-builder $iso1 \
     –size=10G \
     –format qcow2 -o /var/lib/libvirt/images/$iso-vm1.qcow2 \
     –hostname $iso1-vm1 \
     –network \
     –timezone Europe/Sofia


[   3.2] Downloading:
[   4.1] Planning how to build this image
[   4.1] Uncompressing
[  16.9] Resizing (using virt-resize) to expand the disk to 10.0G
[  40.1] Opening the new disk
[  42.9] Setting a random seed
virt-builder: warning: random seed could not be set for this type of guest
[  42.9] Setting the hostname: debian-9-vm1
[  43.6] Setting the timezone: Europe/Sofia
[  43.6] Setting passwords
virt-builder: Setting random password of root to JtzEYGff9KxL5jCR
[  44.3] Finishing off
                   Output file: /var/lib/libvirt/images/debian-9-vm1.qcow2
                   Output size: 10.0G
                 Output format: qcow2
            Total usable space: 9.8G
                    Free space: 9.0G (91%)

vim bridged.xml

  <forward mode="bridge"/>
  <bridge name="br0"/>


# sudo virsh net-define –file bridged.xml
# sudo virsh net-autostart br0
# sudo virsh net-start br0


Above two commands will download pre-packaged KVM isos and store them inside /var/lib/libvirt/images/ you see also the root (administrator) password for both ISOs printed out.


root@jeremiah:/home/hipo/kvm# ls -ld /var/lib/libvirt/images/*
-rw-r–r– 1 root         root         10739318784 Oct 12 23:45 /var/lib/libvirt/images/debian-9-vm1.qcow2
-rw-r–r– 1 root         root         10739318784 Oct 12 23:46 /var/lib/libvirt/images/fedora-28-vm1.qcow2


To access directly the new created VMs as we have specified the –vnc option it is possible to directly vnc to the new host with VNC client (in linux I use vncviewer), on Windows you can use something like TightVNC.

6. Use official Linux distributions ISO boot files to install into KVM VM

Those who would like to run inside KVM VM Linux could do it directly using installable ISO files and install the set of Linux with the required packages, just like installing a fresh new Linux on a bare-metal machine.
To do so download your ISO image from the net (either from official distro website or a mirror website, in case if you need to spin an older version) and use virt-install to run the installer inside KVM.


root@jeremiah:~# cd /var/lib/libvirt/boot/;
root@jeremiah:~# wget


# sudo virt-install \
–virt-type=kvm \
–name centos7 \
–ram 2048 \
–vcpus=2 \
–os-variant=centos7.0 \
–virt-type=kvm \
–hvm \
–cdrom=/var/lib/libvirt/boot/CentOS-7-x86_64-DVD-1804.iso \
–network=bridge=br0,model=virtio \
–network=bridge=br1,model=virtio \
–graphics vnc \
–disk path=/var/lib/libvirt/images/centos7.qcow2,size=40,bus=virtio,format=qcow2

7. List newly created VMs with Virsh command


root@jeremiah:/home/hipo/kvm# virsh list –all
 Id    Name                           State
 3     fedora-28                      running
 –     debian9                        shut off


The –all parameter lists all available VMs ready to spin, if you want to check what are the VMs that are only running use instead:


root@jeremiah:/home/hipo/kvm# virsh list
 Id    Name                           State
 3     fedora-28                      running


8. Install Virtual Machine OS-es

Below lines will install 2 Virtual machines one Fedora 28 and Debian 9


virt-install –import –name $os \
    –ram 2048 \
    –vcpu 2 \
    –disk path=/var/lib/libvirt/images/$os-vm1.qcow2,format=qcow2 \
    –os-variant fedora-unknown \
    –network=bridge=br0,model=virtio \
    –noautoconsole \
  –hvm \
  –graphics vnc

virt-install –import –name $os     \
–ram 2048     \
–vcpu 2     \
–disk path=/var/lib/libvirt/images/$os-vm1.qcow2,format=qcow2     \
–os-variant debian9     –network=bridge=br0,model=virtio     \
–noautoconsole \
–hvm \
–graphics vnc

To deploy more just change the virtual machine type in os variable and modify the –os-variant variable to match the distribution name, to get the correct –os-variant variables that can be passed use osinfo-query below is output of the cmd:


root@jeremiah:/home/hipo/kvm# osinfo-query os
 Short ID             | Name                                               | Version  | ID                                      
 altlinux1.0          | Mandrake RE Spring 2001                            | 1.0      |        
 altlinux2.0          | ALT Linux 2.0                                      | 2.0      |        
 altlinux2.2          | ALT Linux 2.2                                      | 2.2      |        
 altlinux2.4          | ALT Linux 2.4                                      | 2.4      |        
 altlinux3.0          | ALT Linux 3.0                                      | 3.0      |        
 altlinux4.0          | ALT Linux 4.0                                      | 4.0      |        
 altlinux4.1          | ALT Linux 4.1                                      | 4.1      |        
 altlinux5.0          | ALT Linux 5.0                                      | 5.0      |        
 altlinux6.0          | ALT Linux 6.0                                      | 6.0      |        
 altlinux7.0          | ALT Linux 7.0                                      | 7.0      |        
 centos6.0            | CentOS 6.0                                         | 6.0      |            
 centos6.1            | CentOS 6.1                                         | 6.1      |            
 centos6.2            | CentOS 6.2                                         | 6.2      |            
 centos6.3            | CentOS 6.3                                         | 6.3      |            
 centos6.4            | CentOS 6.4                                         | 6.4      |            
 centos6.5            | CentOS 6.5                                         | 6.5      |            
 centos6.6            | CentOS 6.6                                         | 6.6      |            
 centos6.7            | CentOS 6.7                                         | 6.7      |            
 centos6.8            | CentOS 6.8                                         | 6.8      |            
 centos6.9            | CentOS 6.9                                         | 6.9      |            
 centos7.0            | CentOS 7.0                                         | 7.0      |            
 debian1.1            | Debian Buzz                                        | 1.1      |            
 debian1.2            | Debian Rex                                         | 1.2      |            
 debian1.3            | Debian Bo                                          | 1.3      |            
 debian2.0            | Debian Hamm                                        | 2.0      |            
 debian2.1            | Debian Slink                                       | 2.1      |            
 debian2.2            | Debian Potato                                      | 2.2      |            
 debian3              | Debian Woody                                       | 3        |              
 debian3.1            | Debian Sarge                                       | 3.1      |            
 debian4              | Debian Etch                                        | 4        |              
 debian5              | Debian Lenny                                       | 5        |              
 debian6              | Debian Squeeze                                     | 6        |              
 debian7              | Debian Wheezy                                      | 7        |              
 debian8              | Debian Jessie                                      | 8        |              
 debian9              | Debian Stretch                                     | 9        |              
 debiantesting        | Debian Testing                                     | testing  |        
 fedora-unknown       | Fedora                                             | unknown  |
 fedora1              | Fedora Core 1                                      | 1        |       
 fedora10             | Fedora 10                                          | 10       |      
 fedora11             | Fedora 11                                          | 11       |      
 fedora12             | Fedora 12                                          | 12       |      
 fedora13             | Fedora 13                                          | 13       |      
 fedora14             | Fedora 14                                          | 14       |      
 fedora15             | Fedora 15                                          | 15       |      
 fedora16             | Fedora 16                                          | 16       |      
 fedora17             | Fedora 17                                          | 17       |      
 fedora18             | Fedora 18                                          | 18       |      
 fedora19             | Fedora 19                                          | 19       |      
 fedora2              | Fedora Core 2                                      | 2        |       
 fedora20             | Fedora 20                                          | 20       |      
 fedora21             | Fedora 21                                          | 21       |      
 fedora22             | Fedora 22                                          | 22       |      
 fedora23             | Fedora 23                                          | 23       |      
 fedora24             | Fedora 24                                          | 24       |      
 fedora25             | Fedora 25                                          | 25       |      
 fedora26             | Fedora 26                                          | 26       |      
 fedora3              | Fedora Core 3                                      | 3        |       
 fedora4              | Fedora Core 4                                      | 4        |       
 fedora5              | Fedora Core 5                                      | 5        |       
 fedora6              | Fedora Core 6                                      | 6        |       
 fedora7              | Fedora 7                                           | 7        |       
 fedora8              | Fedora 8                                           | 8        |       
 fedora9              | Fedora 9                                           | 9        |       
 freebsd1.0           | FreeBSD 1.0                                        | 1.0      |          
 freebsd10.0          | FreeBSD 10.0                                       | 10.0     |         
 freebsd10.1          | FreeBSD 10.1                                       | 10.1     |         
 freebsd10.2          | FreeBSD 10.2                                       | 10.2     |         
 freebsd10.3          | FreeBSD 10.3                                       | 10.3     |         
 freebsd10.4          | FreeBSD 10.4                                       | 10.4     |         
 freebsd11.0          | FreeBSD 11.0                                       | 11.0     |         
 freebsd11.1          | FreeBSD 11.1                                       | 11.1     |         
 freebsd2.0           | FreeBSD 2.0                                        | 2.0      |          
 freebsd2.0.5         | FreeBSD 2.0.5                                      | 2.0.5    |        
 freebsd2.2.8         | FreeBSD 2.2.8                                      | 2.2.8    |        
 freebsd2.2.9         | FreeBSD 2.2.9                                      | 2.2.9    |        
 freebsd3.0           | FreeBSD 3.0                                        | 3.0      |          
 freebsd3.2           | FreeBSD 3.2                                        | 3.2      |          
 freebsd4.0           | FreeBSD 4.0                                        | 4.0      |          
 freebsd4.1           | FreeBSD 4.1                                        | 4.1      |          
 freebsd4.10          | FreeBSD 4.10                                       | 4.10     |         
 freebsd4.11          | FreeBSD 4.11                                       | 4.11     |         
 freebsd4.2           | FreeBSD 4.2                                        | 4.2      |          
 freebsd4.3           | FreeBSD 4.3                                        | 4.3      |          
 freebsd4.4           | FreeBSD 4.4                                        | 4.4      |          
 freebsd4.5           | FreeBSD 4.5                                        | 4.5      |          
 freebsd4.6           | FreeBSD 4.6                                        | 4.6      |          
 freebsd4.7           | FreeBSD 4.7                                        | 4.7      |          
 freebsd4.8           | FreeBSD 4.8                                        | 4.8      |          
 freebsd4.9           | FreeBSD 4.9                                        | 4.9      |          
 freebsd5.0           | FreeBSD 5.0                                        | 5.0      |          
 freebsd5.1           | FreeBSD 5.1                                        | 5.1      |          
 freebsd5.2           | FreeBSD 5.2                                        | 5.2      |          
 freebsd5.2.1         | FreeBSD 5.2.1                                      | 5.2.1    |        
 freebsd5.3           | FreeBSD 5.3                                        | 5.3      |          
 freebsd5.4           | FreeBSD 5.4                                        | 5.4      |          
 freebsd5.5           | FreeBSD 5.5                                        | 5.5      |          
 freebsd6.0           | FreeBSD 6.0                                        | 6.0      |          
 freebsd6.1           | FreeBSD 6.1                                        | 6.1      |          
 freebsd6.2           | FreeBSD 6.2                                        | 6.2      |          
 freebsd6.3           | FreeBSD 6.3                                        | 6.3      |          
 freebsd6.4           | FreeBSD 6.4                                        | 6.4      |          
 freebsd7.0           | FreeBSD 7.0                                        | 7.0      |          
 freebsd7.1           | FreeBSD 7.1                                        | 7.1      |          
 freebsd7.2           | FreeBSD 7.2                                        | 7.2      |          
 freebsd7.3           | FreeBSD 7.3                                        | 7.3      |          
 freebsd7.4           | FreeBSD 7.4                                        | 7.4      |          
 freebsd8.0           | FreeBSD 8.0                                        | 8.0      |          
 freebsd8.1           | FreeBSD 8.1                                        | 8.1      |          
 freebsd8.2           | FreeBSD 8.2                                        | 8.2      |          
 freebsd8.3           | FreeBSD 8.3                                        | 8.3      |          
 freebsd8.4           | FreeBSD 8.4                                        | 8.4      |          
 freebsd9.0           | FreeBSD 9.0                                        | 9.0      |          
 freebsd9.1           | FreeBSD 9.1                                        | 9.1      |          
 freebsd9.2           | FreeBSD 9.2                                        | 9.2      |          
 freebsd9.3           | FreeBSD 9.3                                        | 9.3      |          
 freedos1.2           | FreeDOS 1.2                                        | 1.2      |          
 gnome-continuous-3.10 | GNOME 3.10                                         | 3.10     |  
 gnome-continuous-3.12 | GNOME 3.12                                         | 3.12     |  
 gnome-continuous-3.14 | GNOME 3.14                                         | 3.14     |  
 gnome3.6             | GNOME 3.6                                          | 3.6      |              
 gnome3.8             | GNOME 3.8                                          | 3.8      |              
 macosx10.0           | MacOS X Cheetah                                    | 10.0     |            
 macosx10.1           | MacOS X Puma                                       | 10.1     |            
 macosx10.2           | MacOS X Jaguar                                     | 10.2     |            
 macosx10.3           | MacOS X Panther                                    | 10.3     |            
 macosx10.4           | MacOS X Tiger                                      | 10.4     |            
 macosx10.5           | MacOS X Leopard                                    | 10.5     |            
 macosx10.6           | MacOS X Snow Leopard                               | 10.6     |            
 macosx10.7           | MacOS X Lion                                       | 10.7     |            
 mageia1              | Mageia 1                                           | 1        |              
 mageia2              | Mageia 2                                           | 2        |              
 mageia3              | Mageia 3                                           | 3        |              
 mageia4              | Mageia 4                                           | 4        |              
 mageia5              | Mageia 5                                           | 5        |              
 mageia6              | Mageia 6                                           | 6        |              
 mandrake10.0         | Mandrake Linux 10.0                                | 10.0     |       
 mandrake10.1         | Mandrake Linux 10.1                                | 10.1     |       
 mandrake10.2         | Mandrake Linux 10.2                                | 10.2     |       
 mandrake5.1          | Mandrake Linux 5.1                                 | 5.1      |        
 mandrake5.2          | Mandrake Linux 5.2                                 | 5.2      |        
 mandrake5.3          | Mandrake Linux 5.3                                 | 5.3      |        
 mandrake6.0          | Mandrake Linux 6.0                                 | 6.0      |        
 mandrake6.1          | Mandrake Linux 6.1                                 | 6.1      |        
 mandrake7.0          | Mandrake Linux 7.0                                 | 7.0      |        
 mandrake7.1          | Mandrake Linux 7.1                                 | 7.1      |        
 mandrake7.2          | Mandrake Linux 7.2                                 | 7.2      |        
 mandrake8.0          | Mandrake Linux 8.0                                 | 8.0      |        
 mandrake8.1          | Mandrake Linux 8.1                                 | 8.1      |        
 mandrake8.2          | Mandrake Linux 8.2                                 | 8.2      |        
 mandrake9.0          | Mandrake Linux 9.0                                 | 9.0      |        
 mandrake9.1          | Mandrake Linux 9.1                                 | 9.1      |        
 mandrake9.2          | Mandrake Linux 9.2                                 | 9.2      |        
 mandriva2006.0       | Mandriva Linux 2006.0                              | 2006.0   |     
 mandriva2007         | Mandriva Linux 2007                                | 2007     |       
 mandriva2007.1       | Mandriva Linux 2007 Spring                         | 2007.1   |     
 mandriva2008.0       | Mandriva Linux 2008                                | 2008.0   |     
 mandriva2008.1       | Mandriva Linux 2008 Spring                         | 2008.1   |     
 mandriva2009.0       | Mandriva Linux 2009                                | 2009.0   |     
 mandriva2009.1       | Mandriva Linux 2009 Spring                         | 2009.1   |     
 mandriva2010.0       | Mandriva Linux 2010                                | 2010.0   |     
 mandriva2010.1       | Mandriva Linux 2010 Spring                         | 2010.1   |     
 mandriva2010.2       | Mandriva Linux 2010.2                              | 2010.2   |     
 mandriva2011         | Mandriva Linux 2011                                | 2011     |       
 mbs1.0               | Mandriva Business Server 1.0                       | 1.0      |             
 mes5                 | Mandriva Enterprise Server 5.0                     | 5.0      |             
 mes5.1               | Mandriva Enterprise Server 5.1                     | 5.1      |             
 msdos6.22            | Microsoft MS-DOS 6.22                              | 6.22     |         
 netbsd0.8            | NetBSD 0.8                                         | 0.8      |            
 netbsd0.9            | NetBSD 0.9                                         | 0.9      |            
 netbsd1.0            | NetBSD 1.0                                         | 1.0      |            
 netbsd1.1            | NetBSD 1.1                                         | 1.1      |            
 netbsd1.2            | NetBSD 1.2                                         | 1.2      |            
 netbsd1.3            | NetBSD 1.3                                         | 1.3      |            
 netbsd1.4            | NetBSD 1.4                                         | 1.4      |            
 netbsd1.5            | NetBSD 1.5                                         | 1.5      |            
 netbsd1.6            | NetBSD 1.6                                         | 1.6      |            
 netbsd2.0            | NetBSD 2.0                                         | 2.0      |            
 netbsd3.0            | NetBSD 3.0                                         | 3.0      |            
 netbsd4.0            | NetBSD 4.0                                         | 4.0      |            
 netbsd5.0            | NetBSD 5.0                                         | 5.0      |            
 netbsd5.1            | NetBSD 5.1                                         | 5.1      |            
 netbsd6.0            | NetBSD 6.0                                         | 6.0      |            
 netbsd6.1            | NetBSD 6.1                                         | 6.1      |            
 netbsd7.0            | NetBSD 7.0                                         | 7.0      |            
 netbsd7.1            | NetBSD 7.1                                         | 7.1      |            
 netbsd7.1.1          | NetBSD 7.1.1                                       | 7.1.1    |          
 netware4             | Novell Netware 4                                   | 4        |             
 netware5             | Novell Netware 5                                   | 5        |             
 netware6             | Novell Netware 6                                   | 6        |             
 openbsd4.2           | OpenBSD 4.2                                        | 4.2      |          
 openbsd4.3           | OpenBSD 4.3                                        | 4.3      |          
 openbsd4.4           | OpenBSD 4.4                                        | 4.4      |          
 openbsd4.5           | OpenBSD 4.5                                        | 4.5      |          
 openbsd4.8           | OpenBSD 4.8                                        | 4.8      |          
 openbsd4.9           | OpenBSD 4.9                                        | 4.9      |          
 openbsd5.0           | OpenBSD 5.0                                        | 5.0      |          
 openbsd5.1           | OpenBSD 5.1                                        | 5.1      |          
 openbsd5.2           | OpenBSD 5.2                                        | 5.2      |          
 openbsd5.3           | OpenBSD 5.3                                        | 5.3      |          
 openbsd5.4           | OpenBSD 5.4                                        | 5.4      |          
 openbsd5.5           | OpenBSD 5.5                                        | 5.5      |          
 openbsd5.6           | OpenBSD 5.6                                        | 5.6      |          
 openbsd5.7           | OpenBSD 5.7                                        | 5.7      |          
 openbsd5.8           | OpenBSD 5.8                                        | 5.8      |          
 openbsd5.9           | OpenBSD 5.9                                        | 5.9      |          
 openbsd6.0           | OpenBSD 6.0                                        | 6.0      |          
 openbsd6.1           | OpenBSD 6.1                                        | 6.1      |          
 openbsd6.2           | OpenBSD 6.2                                        | 6.2      |          
 opensolaris2009.06   | OpenSolaris 2009.06                                | 2009.06  |      
 opensuse-factory     | openSUSE                                           | factory  |    
 opensuse-unknown     | openSUSE                                           | unknown  |    
 opensuse10.2         | openSUSE 10.2                                      | 10.2     |       
 opensuse10.3         | openSUSE 10.3                                      | 10.3     |       
 opensuse11.0         | openSUSE 11.0                                      | 11.0     |       
 opensuse11.1         | openSUSE 11.1                                      | 11.1     |       
 opensuse11.2         | openSUSE 11.2                                      | 11.2     |       
 opensuse11.3         | openSUSE 11.3                                      | 11.3     |       
 opensuse11.4         | openSUSE 11.4                                      | 11.4     |       
 opensuse12.1         | openSUSE 12.1                                      | 12.1     |       
 opensuse12.2         | openSUSE 12.2                                      | 12.2     |       
 opensuse12.3         | openSUSE 12.3                                      | 12.3     |       
 opensuse13.1         | openSUSE 13.1                                      | 13.1     |       
 opensuse13.2         | openSUSE 13.2                                      | 13.2     |       
 opensuse42.1         | openSUSE Leap 42.1                                 | 42.1     |       
 opensuse42.2         | openSUSE Leap 42.2                                 | 42.2     |       
 opensuse42.3         | openSUSE Leap 42.3                                 | 42.3     |       
 opensusetumbleweed   | openSUSE Tumbleweed                                | tumbleweed |
 rhel-atomic-7.0      | Red Hat Enterprise Linux Atomic Host 7.0           | 7.0      |       
 rhel-atomic-7.1      | Red Hat Enterprise Linux Atomic Host 7.1           | 7.1      |       
 rhel-atomic-7.2      | Red Hat Enterprise Linux Atomic Host 7.2           | 7.2      |       
 rhel2.1              | Red Hat Enterprise Linux 2.1                       | 2.1      |              
 rhel2.1.1            | Red Hat Enterprise Linux 2.1 Update 1  
/etc/bind/masters/            | 2.1.1    |            
 rhel2.1.2            | Red Hat Enterprise Linux 2.1 Update 2              | 2.1.2    |            
 rhel2.1.3            | Red Hat Enterprise Linux 2.1 Update 3              | 2.1.3    |            
 rhel2.1.4            | Red Hat Enterprise Linux 2.1 Update 4              | 2.1.4    |            
 rhel2.1.5            | Red Hat Enterprise Linux 2.1 Update 5              | 2.1.5    |            
 rhel2.1.6            | Red Hat Enterprise Linux 2.1 Update 6              | 2.1.6    |            
 rhel2.1.7            | Red Hat Enterprise Linux 2.1 Update 7              | 2.1.7    |            
 rhel3                | Red Hat Enterprise Linux 3                         | 3        |                
 rhel3.1              | Red Hat Enterprise Linux 3 Update 1                | 3.1      |              
 rhel3.2              | Red Hat Enterprise Linux 3 Update 2                | 3.2      |              
 rhel3.3              | Red Hat Enterprise Linux 3 Update 3                | 3.3      |              
 rhel3.4              | Red Hat Enterprise Linux 3 Update 4                | 3.4      |              
 rhel3.5              | Red Hat Enterprise Linux 3 Update 5                | 3.5      |              
 rhel3.6              | Red Hat Enterprise Linux 3 Update 6                | 3.6      |              
 rhel3.7              | Red Hat Enterprise Linux 3 Update 7                | 3.7      |              
 rhel3.8              | Red Hat Enterprise Linux 3 Update 8                | 3.8      |              
 rhel3.9              | Red Hat Enterprise Linux 3 Update 9                | 3.9      |              
 rhel4.0              | Red Hat Enterprise Linux 4.0                       | 4.0      |              
 rhel4.1              | Red Hat Enterprise Linux 4.1                       | 4.1      |              
 rhel4.2              | Red Hat Enterprise Linux 4.2                       | 4.2      |              
 rhel4.3              | Red Hat Enterprise Linux 4.3                       | 4.3      |              
 rhel4.4              | Red Hat Enterprise Linux 4.4                       | 4.4      |              
 rhel4.5              | Red Hat Enterprise Linux 4.5                       | 4.5      |              
 rhel4.6              | Red Hat Enterprise Linux 4.6                       | 4.6      |              
 rhel4.7              | Red Hat Enterprise Linux 4.7                       | 4.7      |              
 rhel4.8              | Red Hat Enterprise Linux 4.8                       | 4.8      |              
 rhel4.9              | Red Hat Enterprise Linux 4.9                       | 4.9      |              
 rhel5.0              | Red Hat Enterprise Linux 5.0                       | 5.0      |              
 rhel5.1              | Red Hat Enterprise Linux 5.1                       | 5.1      |              
 rhel5.10             | Red Hat Enterprise Linux 5.10                      | 5.10     |             
 rhel5.11             | Red Hat Enterprise Linux 5.11                      | 5.11     |             
 rhel5.2              | Red Hat Enterprise Linux 5.2                       | 5.2      |              
 rhel5.3              | Red Hat Enterprise Linux 5.3                       | 5.3      |              
 rhel5.4              | Red Hat Enterprise Linux 5.4                       | 5.4      |              
 rhel5.5              | Red Hat Enterprise Linux 5.5                       | 5.5      |              
 rhel5.6              | Red Hat Enterprise Linux 5.6                       | 5.6      |              
 rhel5.7              | Red Hat Enterprise Linux 5.7                       | 5.7      |              
 rhel5.8              | Red Hat Enterprise Linux 5.8                       | 5.8      |              
 rhel5.9              | Red Hat Enterprise Linux 5.9                       | 5.9      |              
 rhel6.0              | Red Hat Enterprise Linux 6.0                       | 6.0      |              
 rhel6.1              | Red Hat Enterprise Linux 6.1                       | 6.1      |              
 rhel6.2              | Red Hat Enterprise Linux 6.2                       | 6.2      |              
 rhel6.3              | Red Hat Enterprise Linux 6.3                       | 6.3      |              
 rhel6.4              | Red Hat Enterprise Linux 6.4                       | 6.4      |              
 rhel6.5              | Red Hat Enterprise Linux 6.5                       | 6.5      |              
 rhel6.6              | Red Hat Enterprise Linux 6.6                       | 6.6      |              
 rhel6.7              | Red Hat Enterprise Linux 6.7                       | 6.7      |              
 rhel6.8              | Red Hat Enterprise Linux 6.8                       | 6.8      |              
 rhel6.9              | Red Hat Enterprise Linux 6.9                       | 6.9      |              
 rhel7.0              | Red Hat Enterprise Linux 7.0                       | 7.0      |              
 rhel7.1              | Red Hat Enterprise Linux 7.1                       | 7.1      |              
 rhel7.2              | Red Hat Enterprise Linux 7.2                       | 7.2      |              
 rhel7.3              | Red Hat Enterprise Linux 7.3                       | 7.3      |              
 rhel7.4              | Red Hat Enterprise Linux 7.4                       | 7.4      |              
 rhl1.0               | Red Hat Linux 1.0                                  | 1.0      |               
 rhl1.1               | Red Hat Linux 1.1                                  | 1.1      |               
 rhl2.0               | Red Hat Linux 2.0                                  | 2.0      |               
 rhl2.1               | Red Hat Linux 2.1                                  | 2.1      |               
 rhl3.0.3             | Red Hat Linux 3.0.3                                | 3.0.3    |             
 rhl4.0               | Red Hat Linux 4.0                                  | 4.0      |               
 rhl4.1               | Red Hat Linux 4.1                                  | 4.1      |               
 rhl4.2               | Red Hat Linux 4.2                                  | 4.2      |               
 rhl5.0               | Red Hat Linux 5.0                                  | 5.0      |               
 rhl5.1               | Red Hat Linux 5.1                                  | 5.1      |               
 rhl5.2               | Red Hat Linux 5.2                                  | 5.2      |               
 rhl6.0               | Red Hat Linux 6.0                                  | 6.0      |               
 rhl6.1               | Red Hat Linux 6.1                                  | 6.1      |               
 rhl6.2               | Red Hat Linux 6.2                                  | 6.2      |               
 rhl7                 | Red Hat Linux 7                                    | 7        |                 
 rhl7.1               | Red Hat Linux 7.1                                  | 7.1      |               
 rhl7.2               | Red Hat Linux 7.2                                  | 7.2      |               
 rhl7.3               | Red Hat Linux 7.3                                  | 7.3      |               
 rhl8.0               | Red Hat Linux 8.0                                  | 8.0      |               
 rhl9                 | Red Hat Linux 9                                    | 9        |                 
 sled10               | SUSE Linux Enterprise Desktop 10                   | 10       |                 
 sled10sp1            | SUSE Linux Enterprise Desktop 10 SP1               | 10.1     |               
 sled10sp2            | SUSE Linux Enterprise Desktop 10 SP2               | 10.2     |               
 sled10sp3            | SUSE Linux Enterprise Desktop 10 SP3               | 10.3     |               
 sled10sp4            | SUSE Linux Enterprise Desktop 10 SP4               | 10.4     |               
 sled11               | SUSE Linux Enterprise Desktop 11                   | 11       |                 
 sled11sp1            | SUSE Linux Enterprise Desktop 11 SP1               | 11.1     |               
 sled11sp2            | SUSE Linux Enterprise Desktop 11 SP2               | 11.2     |               
 sled11sp3            | SUSE Linux Enterprise Desktop 11 SP3               | 11.3     |               
 sled11sp4            | SUSE Linux Enterprise Desktop 11 SP4               | 11.4     |               
 sled12               | SUSE Linux Enterprise Desktop 12                   | 12       |                 
 sled12sp1            | SUSE Linux Enterprise Desktop 12 SP1               | 12.1     |               
 sled12sp2            | SUSE Linux Enterprise Desktop 12 SP2               | 12.2     |               
 sled9                | SUSE Linux Enterprise Desktop 9                    | 9        |                  
 sles10               | SUSE Linux Enterprise Server 10            
/etc/bind/masters/        | 10       |                 
 sles10sp1            | SUSE Linux Enterprise Server 10 SP1                | 10.1     |               
 sles10sp2            | SUSE Linux Enterprise Server 10 SP2                | 10.2     |               
 sles10sp3            | SUSE Linux Enterprise Server 10 SP3                | 10.3     |               
 sles10sp4            | SUSE Linux Enterprise Server 10 SP4                | 10.4     |               
 sles11               | SUSE Linux Enterprise Server 11                    | 11       |                 
 sles11sp1            | SUSE Linux Enterprise Server 11 SP1                | 11.1     |               
 sles11sp2            | SUSE Linux Enterprise Server 11 SP2                | 11.2     |               
 sles11sp3            | SUSE Linux Enterprise Server 11 SP3                | 11.3     |               
 sles11sp4            | SUSE Linux Enterprise Server 11 SP4                | 11.4     |               
 sles12               | SUSE Linux Enterprise Server 12                    | 12       |                 
 sles12sp1            | SUSE Linux Enterprise Server 12 SP1                | 12.1     |               
 sles12sp2            | SUSE Linux Enterprise Server 12 SP2                | 12.2     |               
 sles9                | SUSE Linux Enterprise Server 9                     | 9        |                  
 solaris10            | Solaris 10                                         | 10       |               
 solaris11            | Oracle Solaris 11                                  | 11       |            
 solaris9             | Solaris 9                                          | 9        |                
 ubuntu10.04          | Ubuntu 10.04 LTS                                   | 10.04    |          
 ubuntu10.10          | Ubuntu 10.10                                       | 10.10    |          
 ubuntu11.04          | Ubuntu 11.04                                       | 11.04    |          
 ubuntu11.10          | Ubuntu 11.10                                       | 11.10    |          
 ubuntu12.04          | Ubuntu 12.04 LTS                                   | 12.04    |          
 ubuntu12.10          | Ubuntu 12.10                                       | 12.10    |          
 ubuntu13.04          | Ubuntu 13.04                                       | 13.04    |          
 ubuntu13.10          | Ubuntu 13.10                                       | 13.10    |          
 ubuntu14.04          | Ubuntu 14.04 LTS                                   | 14.04    |          
 ubuntu14.10          | Ubuntu 14.10                                       | 14.10    |          
 ubuntu15.04          | Ubuntu 15.04                                       | 15.04    |          
 ubuntu15.10          | Ubuntu 15.10                                       | 15.10    |          
 ubuntu16.04          | Ubuntu 16.04                                       | 16.04    |          
 ubuntu16.10          | Ubuntu 16.10                                       | 16.10    |          
 ubuntu17.04          | Ubuntu 17.04                                       | 17.04    |          
 ubuntu17.10          | Ubuntu 17.10                                       | 17.10    |          
 ubuntu4.10           | Ubuntu 4.10                                        | 4.10     |           
 ubuntu5.04           | Ubuntu 5.04                                        | 5.04     |           
 ubuntu5.10           | Ubuntu 5.10                                        | 5.10     |           
 ubuntu6.06           | Ubuntu 6.06 LTS                                    | 6.06     |           
 ubuntu6.10           | Ubuntu 6.10                                        | 6.10     |           
 ubuntu7.04           | Ubuntu 7.04                                        | 7.04     |           
 ubuntu7.10           | Ubuntu 7.10                                        | 7.10     |           
 ubuntu8.04           | Ubuntu 8.04 LTS                                    | 8.04     |           
 ubuntu8.10           | Ubuntu 8.10                                        | 8.10     |           
 ubuntu9.04           | Ubuntu 9.04                                        | 9.04     |           
 ubuntu9.10           | Ubuntu 9.10                                        | 9.10     |           
 win1.0               | Microsoft Windows 1.0                              | 1.0      |            
 win10                | Microsoft Windows 10                               | 10.0     |             
 win2.0               | Microsoft Windows 2.0                              | 2.0      |            
 win2.1               | Microsoft Windows 2.1                              | 2.1      |            
 win2k                | Microsoft Windows 2000                             | 5.0      |             
 win2k12              | Microsoft Windows Server 2012                      | 6.3      |           
 win2k12r2            | Microsoft Windows Server 2012 R2                   | 6.3      |         
 win2k3               | Microsoft Windows Server 2003                      | 5.2      |            
 win2k3r2             | Microsoft Windows Server 2003 R2                   | 5.2      |          
 win2k8               | Microsoft Windows Server 2008                      | 6.0      |            
 win2k8r2             | Microsoft Windows Server 2008 R2                   | 6.1      |          
 win3.1               | Microsoft Windows 3.1                              | 3.1      |            
 win7                 | Microsoft Windows 7                                | 6.1      |              
 win8                 | Microsoft Windows 8                                | 6.2      |              
 win8.1               | Microsoft Windows 8.1                              | 6.3      |            
 win95                | Microsoft Windows 95                               | 4.0      |             
 win98                | Microsoft Windows 98                               | 4.1      |             
 winme                | Microsoft Windows Millennium Edition               | 4.9      |             
 winnt3.1             | Microsoft Windows NT Server 3.1                    | 3.1      |          
 winnt3.5             | Microsoft Windows NT Server 3.5                    | 3.5      |          
 winnt3.51            | Microsoft Windows NT Server 3.51                   | 3.51     |         
 winnt4.0             | Microsoft Windows NT Server 4.0                    | 4.0      |          
 winvista             | Microsoft Windows Vista                            | 6.0      |          
 winxp                | Microsoft Windows XP                               | 5.1      |  


9. Start / Stop listed KVM Virtual Machine


root@jeremiah:~# virsh list –all
 Id    Name                           State
 3     fedora-28                      running
 –     debian9                        shut off


To start debian9 linux virtual machine that is currently off


root@jeremiah:~# virsh start fedora-28
Domain fedora-28 started


root@jeremiah:/home/hipo# virsh start debian9
error: Failed to start domain debian9
error: Requested operation is not valid: network 'default' is not active

root@jeremiah:/home/hipo# virsh net-list –all
Name                 State      Autostart     Persistent
br0                  active     yes           yes
default              inactive   no            yes


root@jeremiah:/home/hipo# virsh net-start default
Network default started

root@jeremiah:/home/hipo# virsh start debian9
Domain debian9 started


10. Attach to running VM with virsh or virt-manager


root@jeremiah:~# virsh list
 Id    Name                           State
 1     fedora-28                      running
 3     debian9                        running

root@jeremiah:~# virsh connect debian9


Note that to make the login prompt appear you have to press enter once after the ^] connection string appears


An alternative way is to use virt-manager GUI KVM desktop management interface and click over the Virtual Machine Guest name, in same fashion like in VirtualBox.



If you have KVM running on your Linux desktop PC / notebook you can also connect via VNC with virsh command.


root@jericho:~# virsh vncdisplay centos7

Another handy thing is to expose the Virtualized Guest OS with VNC in order to be able to connect and manage installation or further Linux configuration via VNC using an SSH Tunnel with port forwarding:


$ ssh -L 5901:


11.  Start / Shutdown / Suspend / Reboot (safe reboot) a VM guest machine domain



root@jericho:~# virsh shutdown debian9
root@jericho:~# virsh start fedora-28
root@jericho:~# virsh suspend debian9
root@jericho:~# virsh reboot fedora-28


12. Remove / Delete KVM Virtual Machines domain


root@jeremiah:~# virsh undefine fedora-28
root@jeremiah:~# virsh destroy fedora-28

Closing words

Using KVM to experiment with different OS distributions is really fun just like you can easily run a number of the major most popular Linux Distributions and a set of different versions. It takes few minutes to have a fully functional Linux to play with and it saves a lot of hassles when dealing with GNU / Linux and FreeBSD, doing so in Virtualbox for me prooved to be much more complicated (not to mention that often Virtualbox had an ugly bugs so even Importing an Appliance as a Guest VM with an official distro OS-es failed with weird errors.
One other very practical use of Kerkel-based Virtualization is if you want to run your servers using own Micro-Services architecture (e.g. run multiple Linux OS-es each running a separate Apache / Nginx / MySQL / PostGreSQL / Backup / Storage) etc. all of it running on a single dedicated server or a self-hosted bare-metal
There are plenty of Web Interfaces for Management KVM (proprietary and free software) that could even futher simplify the use and deploy / destory of KVM VMs.
All that makes possible running your own Linux or Web hosting provider a relatively easy task and seriously could cut business expenses and operational (maintenance) costs.

If you plan to run youw own hosting company, I can help you establish your infrastructure and advise you on the right technologies to use.


How to install / add new root certificates on Debian, Ubuntu, Mint Linux

Saturday, October 21st, 2017


How to add / Installing a root/CA Certificate on Debian, Ubuntu, Mint Linux


 Because of various auditing failures and other security issues, the CAcert root certificate set is slowly disappearing from the Ubuntu and Debian ‘ca-certificates’ package.

That's really tricky because if you're a system administrator or have a bunch of programmers whose needs is to install a new set of root certificates for their freshly develped Application or you have to make a corporate certificates added to debian rootca, then the good news is it is quite easy to install new certificates to deb based distributions.


Given a CA certificate file foo.crt, follow these steps to install it on Debian / Ubuntu:

    Create a directory for extra CA certificates in /usr/share/ca-certificates:


    debian:~# mkdir /usr/share/ca-certificates/extra-certificates


    Copy the CA .crt file to this directory:


    debian:~# cp foo.crt /usr/share/ca-certificates/extra-certificates/foo.crt


    Let Debian / Ubuntu add the .crt file's path relative to /usr/share/ca-certificates to /etc/ca-certificates.conf (the file lists certificates that you wish to use or to ignore to be installed in /etc/ssl/certs)


    debian:~# dpkg-reconfigure ca-certificates


In case you want to include a .pem file to the list of trustable certificates on Debian / Ubuntu, it must first be converted to a .crt file first, you can do that with:


    debian:~# openssl x509 -in foo.pem -inform PEM -out foo.crt


Lets say you want to add some custom Root certificate for exapmle




   debian:~# mkdir /usr/local/share/ca-certificates/
   debian:~# cd /usr/local/share/ca-certificates/
   debian:~# mkdir /usr/local/share/ca-certificates/
   debian:~# wget -P /usr/local/share/ca-certificates/




Then once again update the ca certificates bundle

   debian:~# update-ca-certificates


Gnome Appearance modify command in Linux / How to change theme using command line in GNOME

Friday, October 13th, 2017



1. Gnome Appearance modify command  in Linux instead – Intro

It is always handy to do stuff in console and as a GNU / Linux long time GNOME user I found it interesting to share here some nice tips on how Theme could be changed using command line.

Why would you ever want to change themes through console / Terminal? Well lets say you have to administrate remotely a bunch of GNU / Linux Desktop machines and you have to change themes simultaneously on a multiple hosts, changing theme using the command line then comes really handy.

Besides that in GNOME 3.X.X branch with Unity (yackes) if you have chosen to use GNOME (Flashback /Fallback) or Mate you might find it difficult to change some specifics of the default theme, that is especially true for GNOME (flashback) Fallback like me.

If you heard GNOME Flashback but you never used i and wonder what it is I think it is worthy to say few words about it:

GNOME Flashback is a session for GNOME 3 which was initially called "GNOME Fallback", and shipped as a stand-alone session in Debian and Ubuntu. It provides a similar user experience to the GNOME 2.x series sessions. The differences to the MATE project is that GNOME Flashback uses GTK+ 3 and tries to follow the current GNOME development by integrating recent changes of the GNOME libraries. The development currently lags behind a little but a lot of progress has been made in bug fixing lately. So in short GNOME Fallback is for anyone who wants to stick to GNOME 2.X interface but doesn't want to stick to Mate and wants still to use some more graphical goodies that comes with GNOME 3.

In MATE nowadays there is possibility to relatively Easy add / change appearance and add new themes, there is also the graphical tool called Appearance accessible via mate-control-center command or menus. Using Appearance you can modify themes and Window Decorations, however there is much more that can be done or tuned missing in the MATE GUI using a couple of GNOME desktop environment native commands.


2. List All Installed GNOME themes on Debian / Ubuntu Linux



$ ls -1 /usr/share/themes/|sed -e 's#/##g'


The All system installed theme location directory /usr/share/themes for RPM Linux-es Fedoras / CentOS etc. are identication



3. Change GTK Theme

Below commands are for GNOME 3 based desktop environments this includes also any other GNOME based Graphical Environments or components of GNOME 3 such as (Ubuntu Unity, GNOME 3 Shell/Classic, Cinnamon), and even the old GNOME 2 desktop.

In GNOME 2 it was possible to set various variables directly from gconf-editor including GTK Themes but in GNOME 3 somehow this is no more … so to do we need to use some cryptic commands or use gnome-tweak-tool or MyUnity (Ubuntu Linux users with Unity) but configuration that can be made with them is unfortunately partial so in any case knowing below commands is a necessity to be able to tune up nicely your Linux Gnome Desktop.

And yes it is crazy why on Earth gnome developers scaped out the configuration from gconf-editor and left us with this user unfriendly method. Could it be that someone (Like the big corporations) has the interest to ruin Free Software?? What do you think…

Unity, GNOME 3 Shell/Classic, Cinnamon

In Unity GNOME 3 Shell / Classic and Cinnamon (the default Debian graphical env).

Before we start I recommend you check out what is the current installed and enabled theme, you might want decide to keep it after checking the number of themes available. To check your current installed GNOME theme run:


gsettings get org.gnome.desktop.interface gtk-theme

You see I have 'Adwaita' theme as a default.
Next lets change the gnome GTK theme interface.

gsettings set org.gnome.desktop.interface gtk-theme "Menta"


MATE (In Linux Mate the current fork of GNOME 2 for hardcore GNOME 2 users)


mateconftool-2 –type=string –set /desktop/mate/interface/gtk_theme "Menta"


GNOME 2 (In native GNOME 2 if you still own some old machines with old Debian / Ubuntu / Fedoras etc.



gconftool-2 –type=string –set /desktop/gnome/interface/gtk_theme "Menta"


4. Change WINDOW THEME (Metacity)

Unity, GNOME 3 Classic (Metacity), GNOME 3 Shell (Metacity > Mutter)


gsettings set org.gnome.desktop.wm.preferences theme "Menta"

Cinnamon (Metacity -> Muffin)


gconftool –type=string –set /desktop/cinnamon/windows/theme "Menta"


Note: Cinnamon must be restarted for the change to take effect.

GNOME 2 (In Gnome 2 with Metacity)


gconftool-2 –type=string –set /apps/metacity/general/theme "Menta"


MATE (Metacity)


mateconftool-2 –type=string –set /apps/marco/general/theme "Menta"


Change SHELL THEME (In Gnome Shell and Cinnamon)

GNOME Shell (user-theme extension must be enabled)

gsettings set name "Menta"



gsettings set org.cinnamon.theme name "Menta"



Unity, GNOME 3 Shell/Classic, Cinnamon (Change GNOME3 Color scheme)



gsettings set org.gnome.desktop.interface gtk-color-scheme "bg_color:#e9efe9;fg_color:#444444;base_color:#ffffff;text_color:#333333;selected_bg_color:#6666cc;selected_fg_color:#eeeeee;tooltip_bg_color:#222222;tooltip_fg_color:#dfcfcf;link_color:#cc0099;"

Reset color (if you don't like it):

gsettings set org.gnome.desktop.interface gtk-color-scheme ""


MATE (Mate set color scheme)



mateconftool-2 –type=string –set /desktop/mate/interface/gtk_color_scheme "bg_color:#e9efe9;fg_color:#444444;base_color:#ffffff;text_color:#333333;selected_bg_color:#6666cc;selected_fg_color:#eeeeee;tooltip_bg_color:#222222;tooltip_fg_color:#dfcfcf;link_color:#cc0099;"



Reset color :


mateconftool-2 –type=string –set /desktop/mate/interface/gtk_color_scheme ""


6. GNOME 2 (Again for the old GNome 2 machines to change the GTK Color scheme)


gconftool-2 –type=string –set /desktop/gnome/interface/gtk_color_scheme "bg_color:#e9efe9;fg_color:#444444;base_color:#ffffff;text_color:#333333;selected_bg_color:#6666cc;selected_fg_color:#eeeeee;tooltip_bg_color:#222222;tooltip_fg_color:#dfcfcf;link_color:#cc0099;"


Reset color:


gconftool-2 –type=string –set /desktop/gnome/interface/gtk_color_scheme ""


What about colors, well the #444444 and #22222 and #eeeeee, #333333 seen as color codes in above examples can easily decrypted if you don't know them using a tiny tool called gcolor2
The tool is installable on most Linux distributions with a simple apt-get install gcolor2 or yum install gcolor the tool is convenient and a must have for anyone using Linux for basic design or graphic operations with some program as GIMP / Krita / Inkscape / Vectr / Karbon etc.

All gcolor2 does is to make easy for you to get HTML color codes and convert existing ones into colors for you, here is shot:



While talking about setting color another interesting Graphical tool related to article, that gives you abilities to change colors in GNOME is gnome-color-choose, the tool is really awesome and allows you to do many of the color tunings shown in above examples

# apt-get install –yes gnome-color-chooser

And finally for the gnome theme hungry people, here is a great bonus. If you need a ton of shiny new themes as possibility to set up on your GNOME download and install The Ultimate Edition Themes deb (Debian / Ubuntu Mint) etc. collection (mirrored):

Debian and other deb based distro users can easily download and install with:

linux:~# dpkg -i ultimate-edition-themes-.0.0.7_all.deb


Other Linux users such as Fedora ones and Slackware users (if anyone on Slack uses Gnome since KDE is default by default there), use alien tool to install it or directly open the file with Midnight Commander (mc) and copy the files to the /usr/share/themes dir.


This article is possible thanks to Change Theme Using Command Line in GNOME (Linux) command line examples are taken from there.