Linux on Abel World

Docker master slave MySQL replication

Tue, 11 Dec 2018 09:45:37 +0200

Docker master slave mysql replication can be a bit intimidating, but the basics are actually quite easy, just a bit of a laborious work. As of this example I will use docker swarm. for that I assume you have docker already installed fresh on the machine. My example uses CentOS 7.6, but should be similar on other systems like ubuntu. Enjoy the post!

Get the mysql image:

docker pull percona:5.7

Create a few dirs to hold the structure:

Two separate folders for master and slave.
The cnf directory has the configuration files for mysql
The data directory has the volume of mysql structural data.
The folders called mysql, performance schema and sys should NOT be created. those are done by MySQL server on start.

Restart or reboot production Linux server in a secure way

Fri, 15 Jun 2018 09:15:00 +0200

Restart Process

The following procedure can help you backup the state of a Linux server running software, etc. The idea is to save all the

information that will allow you to go back to the same state after a restart. This can be helpful if you are a beginner or experienced sysadmin and need to restart a production server fast. At the same time make sure you can go back to initial state if stuff does not work automatically.

Backup your servers files and services

MySQL slave master switch

Sat, 01 Jul 2017 17:15:11 +0200

MySQL slave to master switch is an operation required in a few situations. Sometimes master dies and you need to make DB available as soon as possible. In this case if the DB is reasonably big then restoring from backup might take to long. Also keep present that slave has a current copy of data, you might have new data after the last backup that you can not afford to lose. Some other common situations where you might require such a procedure is when you want to upgrade your MySQL servers. For instance from Percona 5.6 to Percona 5.7. Also this will help to avoid long downtime.

Notice: if you have classic master slave replication some downtime is unavoidable, there are different setups that can be done to achieve having a cluster that does not stop working if you take the master offline, but this is NOT the objective of this post.

this post is some what related to another recent post; Mysql DB server OS change / replacement or distro upgrade; study case

Ok, let’s stop the chitchat and let’s get some stuff done.

Mysql DB server OS change / replacement or distro upgrade; study case

Tue, 27 Jun 2017 09:35:17 +0200

Mysql DB server OS change:

Mysql DB server OS change might be required in different situations, but for those who do not know what I am talking about, let me start by explaining what this is and why you might need it in some situations. Just to serve as an example; let say you are renting a few Virtial Machine Server from X IDC or cloud provider. This cloud provider gave you an a distribution that in 2013 had 4 years of support and everything was cool, you installed you systems. Now is 2017 and you need an upgrade. Let me give more details.

You are running a web environment with load balancers, web-server, and 2- Mysql DB servers Master and slave replication, etc. Your application needs High availability and you can not afford to have a lot of downtime. Your system is running fine, but last month you got a notification that the EOL (End of life) of your distribution is in 2 months. You also you noticed that your Percona MySQL DB 5.5 has a few limitations that you want to resolve by upgrading toPercona MySQL DB 5.6 or 5.7. So this is the perfect opportunity to upgrade the system and not remain with a legacy OS that will lose support soon. So now you know all you need to know and you are decided to go with progress and make a difference with the change.

You contact your provider about upgrading your system. They reply with a link (URL) to their FAQ saying that they do not support system upgrade. Then you start reading about it and notice that many virtualization services providers do not really support the upgrade. So you can not just du apt-get dist-upgrade. Not that you can not try, but you will likely not succeed, own experience here long ago when I was young and stupid. Maybe your provider supports it, but you might have grown fond of some other distribution over time and you want to change let say from Debian to Redhat or vise-versa, change of company policy, etc. So reason for wanting to change are many.

Hosting network services services and websites basics

Thu, 12 Nov 2015 19:47:53 +0200

Hosting network services and websites or blogs like this one is now a days a regular task of anyone who want to conduct a successful business. This is non written a requirement for many other activities as well. If you are not an ICT professional and you have a website or need to deploy some services in your business and you wander where to store them and how. Then this article is for you.

More people than you might think want to get a server at their home or office and host their own websites and services locally. I am not 100% against this type of solutions, but the truth is the all the odds now a days are against it unless you have a particularly special need to have it locally. Let see what are the drawbacks.

Fedora Linux review & personal experience.

Tue, 10 Mar 2015 09:55:06 +0200

Fedora Logo

Good day, today I am going to talk about Fedora Linux, I can not say I am a great Fedora expert. I have been following the project for a while. but I have decided to install the workstation just a few days ago. My main experience is with Debian based distros, Mint, Ubuntu. I kind of know the system, I have been working with it for around 8 years as developer, network administrator, consultant and enthusiastic. I love Linux, but redhat was never an option for me, and it’s not an option at least for server. I am going to talk about Fedora, the workstation. Fedora is a Red hat based system, well actually fedora is the testing red hat, and in any case they are the same family. I my case this is what happened.

I have a laptop ASUS X750J; it’s a very good laptop for my personal needs. It has a core i7, 6Gb or RAM, 750 HDD. The thing is, even with my experience I never managed to configure properly any of my favorite Operating Systems; as I said Debian, Mint or Ubuntu. So I started looking around for options, I decided to try Fedora 21. The experience is amazing, everything worked from the start.I did not even had to modify a single configuration.

Web hosting administration software free alternative.

Thu, 29 Jan 2015 10:35:17 +0200

Hi, have engaged myself on a quest to look for an administration panel for my customers hosting. I want a good one to have it as an alternative to

Web Hosting

cPanel, the truth is that every day I like the cPanel project less and the free alternatives are getting better. So unless you are committed for some MAJOR reason to cPanel I would not recommend it any more. Use any other GLP like thing from out there, if the problem is support get better support from one of the communities.

LDAP linux configuration and install from source

Sun, 11 Jan 2015 21:37:35 +0200

Hi, if you want to configure LDAP (OpenLDAP) properly and you have never done it, I advise you to read a lot of

LDAP tree

nonsense out there that people write on blogs like mine, before actually trying. After reading a lot of that the you can try, and let me tell you a secret, the best documentation is the one that they provide on their own website, just that sometimes that one is a bit complex to understand.

Well fist the fist, my LDAP version 2.4 never worked installing from repositories on Debian 7. How unable am I or how silly… I don’t know. Bot it did not work as it use to do with earlier versions. I was unable to set the user, password, domain and those initial things using the installer package.deb and dpkg-reconfigure. So I decided immediately that if I am losing the power of having a repository because of this nonsense, then I do not need them any more. I am going to compile the package myself from source. I tried so… but I struggled with the ./configure options. I could not fins the proper ones. and this error report thread gave me the clue to be able to follow the LDAP manual.

After reading this manual I ended up with a file that contains this:

Network segmentation for business

Thu, 08 Jan 2015 19:55:09 +0200

Network segmentation was created to help dividing network from each other. Wikipedia defines it as: “Network

Network Segmentetion

segmentation in computer networking is the act or profession of splitting a computer network into sub-networks, each being a network segment or network layer. Advantages of such splitting are primarily for boosting performance and improving security.”

The applications of this are infinite in now a days business world. Let me just explain a little about my customer particular case.

I decided to write this Network segmentation post due to our last client. He is a hotel owner. The hotel has a lot of rooms. They had a network of a few staff computers plus all the customers computers. The customers access the network using WiFi. Just to serve as an example the customers were on the same network as the accounting computer. That is not a good idea. For instance the day that I was deploying the server at the hotel. I had to cut the network for a few minutes. A customer came to complain and guess what. He was an IT guy. He came saying to me things like the IP address from today is different from the one I had yesterday. I did an NSLOOKUP and it says bla,bla,bla. This guy turned to be a really nice guy, but not everyone has a good heart and intentions.

So because of an incident the owner called me to find a solution. He wanted a few more things. Here is part of a presentation we did for him.

GLPI ticket system & Inventory solution a very viable solution

Tue, 06 Jan 2015 16:00:10 +0200

Team work organization solutions with GLPI

Have a problem to organize team work? have problem to document and follow performance? You do not have satisfactory the statistics about the work done! Have you ever had problems to find simple reports like who is the best worker of the month? Have problems planning resources for the department? Do not know how many computers and other equipment are in the network?

You can use GLPI to solve all those problems. I have a few years of experience maintaining these type of servers for different environment and customer needs. lso I decided to write this post and share some of the things that you can get with GLPI. The main features of GLPI are:

Inventory of computers, peripherals, network printers and associated components through an interface with OCS Inventory or FusionInventory.

Management of issues on many environments through creation of tickets, management of tickets, assignment, tickets scheduling, etc.

Licenses management (ITIL compliant)

Assignment of equipment by geographical area to users and groups

Management of business and financial information (purchase, guarantee and extension, damping)

Equipment status management

Management of applications for assistance of all types of equipment inventory

Interface to allow the user to file a support ticket

Business management, contracts, documents related to inventory items

Equipment booking

Management of a Frequently-Asked Questions (FAQ).

Report generator: hardware, network or interventions (support).

Multilingual support with 45 languages available.

Git client configuration for a local server.

Fri, 04 Jul 2014 18:03:31 +0200

Gitlab Logo

Configuring a git client can be painful sometimes if you are a beginner. I struggled the first time I configured git too. So I am creating this material for others like me to be able to configure git. I hope it works for you. Git is now a days one of the most popular versioning systems. I use git since a few months ago to keep my Symfony 2 projects update.

Configure gitclient with you User name:

git config --global user.name "Abel Guzman"

Squid proxy server working example Debian GNU Linux

Tue, 20 May 2014 11:40:29 +0200

Hello guys, this is post is about an squid working example. The version of the squid that I am running is

2.7 stable. you can check it out running:

root@khs01sw10:~# squid -v
Squid Cache: Version 2.7.STABLE9
configure options:  (...)
root@khs01sw10:~#

Squid 3 error page

Note: Uprated on november 25, 2015

This post is part of a bigger Debian material that you can access here. If you need to know first the basics about squid configuration, you can check out here.

Now, the network that I have configured the proxy for. Is a 300 PC network with the following range 10.175.0.0/23 (net mask 255.255.254.0). The IP address of the proxy is 10.175.0.1. My proxy uses a few father proxies.

Squid3 proxy with Linux debian jessie 8.

Fri, 16 May 2014 16:25:02 +0200

squid3 logo

Squid3 proxy server is the subject of this post, along this writing I am going to show you how to install and configure this proxy server. For more information you can visit this URL; the official website of the project. My system is a Debian jessie 8.

This post is part of a bigger Linux and Debian basic administration material that you can access here. I have also described a squid 2.7 working configuration here. Squid 2.7 is a bit different from squid3 but they are configured basically the same way except for a few new directives and some other changes and deprecations. Let’s play then.

Installing squid3 is simple:

VirtualBox Virtual machine in Linux- Class 7

Tue, 13 May 2014 09:15:31 +0200

Virtualbox is today’s posts subject . We will talk about virtualization and how to virtualize a box using Virtualbox. To start we need to know what is virtualization and its advantages.

virtualbox logo

Virtualization, in computing, refers to the act of creating a virtual (rather than actual) version of something, including but not limited to a virtual computer hardware platform, operating system (OS), storage device, or computer network resources.

Taken from: http://en.wikipedia.org/wiki/Virtualization on 2014-04-22.

This post is part of a bigger Debian material that you can access here.

Apache 2 web server; install and config a virtual host

Tue, 08 Apr 2014 11:08:07 +0200

Good day; today we will install a web server using Apache 2. We will specifically use apache because there are many web servers out there, and apache is probably the most popular one even among windows users, when you install Wamp Server, or Xamp,

Apache Web Server

you are also installing apache 2.x. It has some other advantages or benefits like Openness, a lot of features, extensibility, portability, cost, simple administration, reliability, flexibility, etc. Check out this link for some explanations. It has also some downsides or disadvantages like for instance; it’s Written By Geeks, For Geeks. That does not mean is difficult or any thing like that, but it can be twisted for some specific situations.

The Linux philosophy to install a software like Apache 2 is different from Windows. Windows tries to solve all of your problems at once, Linux’s philosophy is to solve only one of your problems using the best practices. Each of this ways of thinking has it pros and cons, but that is not the objective of this class, so we move on.

To install the package you have to do:

aptitude install apache2

DNS Bind 9 Linux Server Debian; Class 5

Mon, 24 Mar 2014 12:18:48 +0200

Hello, today I will try to teach how to configure a DNS (Domain Name Server or System). “Putting a DNS server on a network allows for the replacement of IP addresses of individual machines by a name. As a result, it’s

DNS

even possible to associate multiple names to the same machine to update the different available services. For example, www.example.com and pop.example.com, could both point to the primary server where the mail server and the business intranet reside, and the domain could be example.com. It’s easy to remember that these two services are running on the same machine whose IP address is 192.168.0.1.

Note: This post is part of a bigger Debian GNU-Linux material that you can access here.

Content

DNS Installation
Configuration
Test the service
Setting up the client

Now imagine that our network administrator decides for some reason or another to move the mail server to the machine 192.168.0.11. The only thing that has to be changed is the DNS server configuration file. You could always go and modify the host configuration for all the users, but that would be time consuming and inconvenient.”

Taken from: https://wiki.debian.org/Bind9 on 2014-03-19

This sounds simply great! But how do we do it?

DHCP server installation and configuration linux Debian; ISC DHCP Server

Wed, 05 Mar 2014 11:30:53 +0200

The Protocol

DHCP server basic principles; installation and configuration; ISC Server on a Debian Linux system.

This post is part of a bigger Debian material that you can access here.

Content

The DHCP protocol
Precautions before we start
Installation of ISC DHCP Sever.
Configuration of the server.
Checking the results

Debian; file system, superuser, commands, configuring and installing

Tue, 04 Mar 2014 12:34:35 +0200

Along this Debian class we will deal with the following. Debian file system, superuser, editing text files, executing commands in the shell, configuring, installing and uninstalling packages.

This post is part of a bigger Debian material that you can access here.

Debian File system, users and superusers; Introduction.

Debian GNU Linux uses the superuser paradigm. In computing, “the superuser is a special user account used for system administration. Depending on the operating system, the actual name of this account might be: root, administrator, admin or supervisor. In some cases the actual name is not significant, rather an authorization flag in the user’s profile determines if administrative functions can be performed. In operating systems which have the concept of a superuser, it is generally recommended that most application work be done using an ordinary account which does not have the ability to make system-wide changes.”

Taken from: http://en.wikipedia.org/wiki/Superuser on 2014-02-16

Debian Linux is of course a system with the superuser paradigm, by default the superuser name is root. But root might refer also to other parts of the system. Root is where every thing starts in Linux systems is like the alpha of the system. Is the “father

directory” (root directory represented by / ) in the file system. And root is also the “superuser”. to see the root directory you can execute the ls command from the fist class.

ls /

ls -la /

and to know if your current user is root you can use the whoami command also from the first class.

whoami

The root user is the privileged user of the system and is a lot more powerful than the Windows administrator; this user can even destroy the systems and it will not be even waned about it. The concept behind it is that this user should only be used when is strictly required. As you might already figure out you need to be extremely careful when working with this user. A lot of power comes with a lot of respectability. To continue with the root user now we will learn a command that helps to change your session to other users. ler say you are rafael and you want to change to miguel or to root. Well “su” is the command that you can use for that un debian and in most Linux systems. You can execute this command by it self:

su

Now it will prompt you for the root password and after you introduce it correctly it will change to the root user. Or if you want to change to a specific user you can use su, followed by the user name.

su class

To know the user you are in you can use the who am I command again.

whoami

As some of you might have noticed there is a small difference in the prompt between the root user and the non-privileged user. the non-privileged user appears in the shell with a $ and the root user with a # symbol. Check out this example:

abel@khs01wxl001:~$ whoami
abel
abel@khs01wxl001:~$ su
Password:
root@khs01wxl001:/home/abel# whoami
root
root@khs01wxl001:/home/abel# su abel
abel@khs01wxl001:~$ whoami
abel
abel@khs01wxl001:~$

The linux systems and Debian as one of them works like a cage for users. If you are abel and you execute su, then you login to root. But the session for abel does not end. After you execute su and change to root you can go back to your old session. To do that you just have to execute the command “exit” and it will take you back to the old user.

Before we continue with other content related to the file system and the super user. Let me introduce a few other commands and concepts.

System restart and shutdown; init run levels-command

init 0 – Shootsdown the computer. DEPRECATED in favour of “shutdown -h”
init 6 – Reboots the system.DEPRECATED in favour of shutdown e.g.: “shutdown -r +1”

Homework A:

What are the init run levels?
There are other init run levels from 1 to 5. What do they do?

Command to view current the network configuration; ifconfig.

“The ifconfig is used to configure the kernel-resident network interfaces. It is used at boot time to set up interfaces as necessary. After that, it is usually only needed when debugging or when system tuning is needed.

If no arguments are given, ifconfig displays the status of the currently active interfaces. If a single interface argument is given, it displays the status of the given interface only; if a single -a argument is given, it displays the status of all interfaces, even those that are down. Otherwise, it configures an interface.”

Taken from ifconfig Debian official manual (man ifconfig)

Tor now we will use it just to view the network interface to view the interfaces configuration you just have to insert the command as root.

root@khs01wxl001:/home/abel# ifconfig 
eth0      Link encap:Ethernet  HWaddr 70:71:bc:b9:34:ad  
          inet addr:10.175.0.146  Bcast:10.175.1.255  Mask:255.255.254.0
          inet6 addr: fe80::7271:bcff:feb9:34ad/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:29874506 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1161761 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:5595877026 (5.2 GiB)  TX bytes:213607775 (203.7 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:333529 errors:0 dropped:0 overruns:0 frame:0
          TX packets:333529 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:123740836 (118.0 MiB)  TX bytes:123740836 (118.0 MiB)

root@khs01wxl001:/home/abel#

Feel free to research about this very useful command.

Remote connections using ssh protocol.

“OpenSSH is a FREE version of the SSH connectivity tools that technical users of the Internet rely on. Users of telnet, rlogin, and ftp may not realize that their password is transmitted across the Internet unencrypted, but it is. OpenSSH encrypts all traffic (including passwords) to effectively eliminate eavesdropping, connection hijacking, and other attacks. Additionally, OpenSSH provides secure tunneling capabilities and several authentication methods, and supports all SSH protocol versions”

Taken from: http://www.openssh.com/ on 2014-02-16.

In the other hand, the Debian Official CD version comes with the ssh client installed by default. (that means you can use it to connect to ssh servers). And the ssh server can also be installed from repository. here is as example of how to connect through ssh.

root@khs01wxl001:~# ssh root@10.175.0.1

root@10.175.0.1's password:

Linux khs01sw10 2.6.325amd64 #1 SMP Mon Sep 23

22:14:43 UTC 2013 x86_64

(...)

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to

the extent

permitted by applicable law.

Last login: Mon Feb 17 15:50:11 2014 from 10.175.0.167

root@khs01sw10:~#

Here in the first line you basically say that you are going to use ssh to connect with root at the host 10.175.0.1 (ssh root@10.175.0.1). If your connection is fine, the remote host has a ssh server running and you are allowed to connect from your IP address then you will be prompted for the password. Then insert the password and press enter and thats is it. You should login be logged in to the remote system. Only then you can execute any command on the remote system, like for instance init 6 to restart the remote system or also you can perform any other task there.

Mount command

As an additional homework lets call it B -I leave you the mount mount command

# mount

Research about how can we use the mount command?

File system Linux vs Windows

Organization of the root directory and HDDs in Linux.

To organize the file system most modern Linux distribution like Debian use the File system Hierarchy Standard. That is an agreement between some authorities of the Free software, some companies and individuals to improve the systems efficiency and interoperability. As per Wikipedia:

The Filesystem Hierarchy Standard (FHS) defines the directory structure and directory contents in Unix and Unix-like operating systems, maintained by the Linux Foundation. The current version is 2.3, announced on 29 January 2004.[1]

Taken from: http://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard

on 2014-02-16.

You can find more information about it here and here. but for now to continue let me just mention the main directories that we will use along

FHS

This classes. Please feel free to user the ls command and also the CD command from class 1 to understand this structure.

/etc – Configuration files for most of the
softwares eg: ssh, network, dhcp, etc.
/home – users folder exept for the root user
eg: class, abel, pedro, miguel, etc.
/var -variable data eg: databases, caches,
logs.

And secondly we will also work with:

/media- Is the mounting point for removable media.
/mnt- mounting point for temporary mounted file systems.
/boot- boot loader static files.
/bin – essential user command binaries

Also we will work with the root user’s folder. So I will leave a homework, for you to research about it.

Homework C:

Where is the root user folder?

Now to continue with the class lets first learn hot to edit with nano.

Editing files with nano.

“nano is a text editor for Unix-like computing systems or operating environments using a command line interface. It emulates the Pico text editor, part of the Pine email client, and also provides additional functionality. In contrast to Pico, nano is licensed under the GNU General Public License.”

Taken from: http://en.wikipedia.org/wiki/Nano_%28text_editor%29 on 2014-03-04

There are some other text editors like vi or vim both also for the shell and gedit or leafpad for the graphic interface. You can use the one you want or can. But in this classes I will assume you are using nano. Basics with nano:

To edit a file: $ nano /path/to/file.\
Nano internal commands:
- CTRL + x: closes the file.
- CTRL + o: saves.
- CTRL + c: cursor position.
- CTRL + k: cuts from nano.
- CTRL + y: paste to nano from nano
- CTRL + C cancels the current action if it’s not finished or says information about the cursor’s position.

Exersice 1: Create a text file called class1 in /home/class. Write some content and practice the commands from last slide.

The repository

“Commmonly refers to a storage location, often for safety or preservation. Many software publishers and other organizations

maintain servers on the Internet for this purpose, either free of charge or for a subscription fee. Repositories may be solely for particular programs, such as CPAN for the Perl programming language, or for an entire operating system. Operators of such repositories typically provide a package management system, tools intended to search for, install and otherwise manipulate software packages from the repositories. For example, many Linux distributions use Advanced Packaging Tool (APT), commonly found in Debian based distributions, or yum found in Red Hat based distributions. There are also multiple independent package management systems, such as pacman, used in Arch Linux and equo, found in Sabayon Linux.”

Taken from: http://en.wikipedia.org/wiki/Repository on 2014-02-16.

Now as the repository is formed by packages we have to define. What is a package?

“A package format is a type of archive containing files and additional metadata found on packages.While the archive file format itself is unchanged, package formats additionally specify the contents, such as requiring a manifest file or certain directory layout. The term is particularly used on Unix systems, and there are several formats available, both for Linux distributions and BSD systems, though the concept also includes pkg files on Mac OS X, MSI files on Windows, JAR files for Java, among others.”

Taken from: http://en.wikipedia.org/wiki/Linux_packages on 2014-03-04.

An other valid definition for package could be this one:

“In Linux distributions, a “package” refers to a compressed file archive containing all of the files that come with a particular application. The files are usually stored in the package according to their relative installation paths on your system. Most packages also contain installation instructions for the OS, as well as a list of any other packages that are dependencies (prerequisites required for installation.”

Taken from: http://www.internetblog.org.uk/post/1520/what-is-a-linux-package/ 2014-03-04.

Debian Package Management

apt-get – package manager

aptitude – higher level package manager.

aptitude install ssh
aptitude install mc

Homework C –

What us the diference between:

aptitude update
aptitude install
aptitude upgrade

How do you remove a packege?

How can you search for a package?

And that is it for today. On the next class we will discus about the package manager and we will install a DHCP server. be ready for it.

Network and DNS configuration Debian Linux - Class 4

Mon, 03 Mar 2014 12:38:31 +0200

Network and DNS client configuration; introduction

Network use of CPU resources

This post is part of a bigger Linux Debian administration material that you can access here.

Today we will deal with network and DNS configurations from command line. The graphical interface has different tools to configure the network and DNS, but this is a servers administrators post; so we will configure every thing from the command prompt. if you need more basic material explaining other aspects about Linux, Debian, basic commands etc, than you can go to the whole index of materials. We will only deal with IP version 4 (IPv4), but IPv6 is pretty similar. So you can learn IPv4 and then configure a network and DNS with IPv6 with just a few changes.

Debian GNU/Linux Introduction Class 1

Fri, 28 Feb 2014 10:40:19 +0200

Debian Linux Evolution.Introduction to GNU-Linux. Linux Environment in Princess Marina Hospital; Servers, services and workstations.

This post is part of a bigger Debian material that you can access here.

Even when this GNU/Linux Debian classes are for Information Technology personnel if you are starting you might have a lot of question.

What is Debian? What is Linux? What is GNU? What is Debian GNU/Linux? what is a Distrubution? A Kernel? Are they all the same? Is Linus Torvalds the author of every thing?

Not intending to answer all of them I will just quote some clever guys from out there.

Content:

The Kernel
Linux – GNU/Linux
Debian
The command prompt

The Kernel

Kernel

“A kernel is the central part of an operating system. It manages the tasks of the computer and the hardware -most notably memory and CPU time. There are two types of kernels:

A microkernel, which only contains basic functionality;
A monolithic kernel, which contains many drivers [Linux].

A computer user never interacts directly with the kernel. It runs behind the scenes and cannot be seen, except for the text logs that it prints.”

Taken from: http://simple.wikipedia.org/wiki/Kernel_%28computer_science%29 on 2014-02-12

Nice and simple, so the kernel is the middle man between me and the computer hardware.

Linux – GNU/Linux

“Many Linux users are familiar with Linux being called “GNU/Linux”. This means something special. “GNU” refers to the userland and “Linux” refers to the kernel. Now, you may be wondering if these two components can be swapped. Yes, they can.
For example, in the beginning of Linux’s history, the GNU community had no kernel at the time and Linux was just a kernel. So, they put the two projects together. Today, the GNU community has a kernel called “Hurd”.
They then swapped the Linux kernel with the Hurd kernel to make “GNU/Hurd” systems. For instance, Arch exists as “GNU/Linux” and “GNU/Hurd”.
Not only do various userland and kernel combinations exist, there are different Linux kernels. Also, Linux is not the only perating system with a module (obvious, right?).”

Taken from: http://www.linux.org/threads/the-linux-kernel-types-of-kernels.5409/ on 2014/02/11.

Evolution Of Linux

The fist bullet is very important where he says that a lot of Linux users are aware that the term GNU/Linux.That GNU is the part of the Operating System (OS) that does the direct work with the user (understand that user does not mean only someone who is using a computer). Then Linux refers to the kernel only, that is the part of the OS that interacts with the hardware.

So basically they have joined GNU and Linux and created GNU/Linux. Of course afterwards both projects have evolved and improved their different components. And an other incredible thing that happened was that when people saw that they could take the Software modify it and create their own new code and make it available again, more and more people started to cooperate to create their own versions of GNU/Linux or to contribute to existing ones. Check out the picture to get a rough idea of what I am talking about.

This next picture is a summary of only the most important GNU/Linux distributions created after the code was released for free. What happened at that time was that some distribution appeared and they evolved to our days becoming better and better and better. Also in important to remark that every time that someone does a good contribution this code is free (generally) and it is incorporated again in other distributions making every generally better or at least more updated with the latest free software.

Linux distribution time-line evolution

The main branches on this graphic are Red Hat from 1994 with child distributions like Mandrake, PCLinux, CentOS, Mandriva, Fedora Core and some other important distributions. Also we have Suse Linux also from 1994 made by Novel Enterprices. An other of the important branches id Debian, it was started back on 1993, for more information read the following paragraph taken from Debian’s project website.

“The Debian Project was officially founded by Ian Murdock on August 16th, 1993. At that time, the whole concept of a “distribution” of Linux was new. Ian intended Debian to be a distribution which would be made openly, in the spirit of Linux and GNU … The creation of Debian was sponsored by the FSF’s GNU project…”

Taken from: https://www.debian.org/doc/manuals/project-history/ch-intro.en.html on 2014/02/28

Now from Debian we also have a whole lot of good derived distributions, like for instance Knopix,Dam Small Linux or the Ubuntu family that started on 2004.Otherwise along this classes we will be working with Debian mostly. But at the end if you know how to work with one of the distributions. You are very likely to be able to work with other distributions with small or no help.

Debian

“The Debian Project (…) is a free operating system. An operating system is the set of basic programs and utilities that make your computer run. At the core of an operating system is the kernel. The kernel is the most fundamental program on the computer and does all the basic housekeeping and lets you start other programs.

Debian systems currently use the Linux kernel or the FreeBSD kernel. Linux is a piece of software started by Linus Torvalds and
supported by thousands of programmers worldwide. FreeBSD is an operating system including a kernel and other software.
However, work is in progress to provide Debian for other kernels, primarily for the Hurd. The Hurd is free software produced by the GNU project.”

Taken from: http://www.debian.org/intro/about#what 2014/02/11.

To get more information about the GNU/Linux and Debian you can go to the official websites:

Debian Project: www.debian.org
Linux Project: www.linux.org
GNU project: www.gnu.org

Gnome

An other of the Linux myths if that Linux has no graphic interface or very rudimentary ones, the true is that there are some very good projects with great future, although there is still a lot to be done. For instance we have Gnome Prject, check out the image, we can get more information about this project here. but Linux has a lot other graphic interfaces among them KDE the closest competitor to gnome or fresh one like LXDE and XFCE. But this classes are not for graphic fans but for Network administrators, so I will not talk to much about graphics any more along the course. We will use the Text Terminal mostly, the scary black Screen that many people are afraid of. The true is that this terminal is very pwoerful and you can perform a lot of activities nicely using it, and also most of the work is not like rocket sciences so we can learn it and that is what we will do along the classes.

Debian and Linux command prompt

We are going to start with real Linux. So if you do not have your Debian GNU/Linux workstation this is the moment to get it. the first thing that we will do is to change to a text terminal you can do that by pressing:

CTRL+ALT+(F1 to F6) Opens a Text terminal.

Now to switch back to the graphic terminal you can press:

Alt+F7 Opens the graphic terminal.

And you can also open a terminal from the graphic interface of your computer. by going to activities and typing terminal in the search box.

Linux Terminal

If you open the you text terminal (black screen) you have to login with a user, because it will prompt you immediately, there you are supposed to put your user and your password. As a curious detail in the Linux terminal when you type a password it does not show the dots that we might be used to in other systems, so someone might think that is not typing but the terminal is really recording every key that you press. This was done that way for security reasons.

Once you are in you can type commands already, lets do for instance:

whoami.

It should return your user name.

root@khs01sw10:~# whoami 
root
root@khs01sw10:~#

Debian man command linux

So running commands is simple. But this is not it, if you do not know how to use a command you can use the commandman passing an other command as augment and it will tell you what it does.

man <CommandIDon’tKnow>

for instance:

root@khs01sw10:~# man whoami

And it will show you the Linux manual for the command. the manuals are always something like the picture. Also if it is not enough you can go to Internet and research about ways of using any command. To get out of the manual you can just press q key and it will exit the manual.

That is what I had prepared for today, let me just add the homework that you can do using the manual and we will met in the next class.

Homework: Explain how to use this commands on a Debian environment.

Whoami
 man
 pwd
 ls -la
 passwd user
 cd
 mkdir
 rm

Thank you for your time.

Linux Server Classes (Introduction)

Thu, 27 Feb 2014 14:39:18 +0200

Linux Server Classes; About this group of materials.

Linux Versions with Tux

I have started this post to bring Linux classes to any one in Gaborone, Botswana. Also you can access and use this materials any where else in the world. The only conditions is that you have to be willing to learn new and useful stuff from the free software movement. This Linux skill sharing was done for the ICT staff in Princess Marina Hospital in Gaborone, Botswana. The main objective was to socialize the Linux knowledge. These skill sharing classes are not part of any certified course. They are just the product of the personal experiences of a Linux and windows network administrator. Linux is currently being used at the hospital in most of the servers and a few workstations. But the course is thought as a General introduction to networking using GNU Linux Debian.

GLPI for technical support, the free tickets System.

Sat, 09 Nov 2013 10:34:41 +0200

GLPI Statistic Charts

GLPI is a free Tickets System distributed under GNU/GPL license. But When do you need a ticket system like this? This is one of the biggest challenges of the technical support companies or technical support teams. If they have to deal with many customers and the response times are critical. To be able to track, follow and organize the work of the different technicians that are supposed to do the actual job. In this scenario the paper work always becomes a challenge, accessibility, loose of information, spell and writing errors, individual and collective statistics, reporting, etc.

Useful Notes as a solution to punctual problems

Fri, 08 Nov 2013 18:20:21 +0200

I tend to forget where I find the solution for my problem very often, so I will start recording some of the solutions that I find for my different problems, if any one find this list some how interesting or useful in the future please consider leaving a comment or suggest other useful information that you have found in internet:

htpasswd Apache 2 authentication with exeption ip.

Thu, 31 Oct 2013 14:26:41 +0200

htpasswd? Hi guys, today I’m just bringing a note about htpasswd hope it will be useful for someone as this knowledge has been for me.

htpasswd is a tool for apache able to secure folders in a web directory, that means that the folder is public, but protected with password. this functionality is very useful for instance to install systems that have no internal security like Sarg the web app to read Squid logs, Munin to read servers performance, also if you want to share a folder with a friend or even when you need to secure your own web applications and you do not want to create your own security module. in the other hand; htpasswd supports several authentication methods with different security level, but I am just going to describe the basics authentication.

Symfony 2 hosting server

Wed, 09 Oct 2013 06:54:35 +0200

Symfony again! Hello, as you know I like to hit my head against the screen from time to time. So today I’m going to try to configure a server to host Symfony Aplications. The host in this case will be a virtual machine in my own computer.

Note: this post is about how to install Symfony, how to meet the requirements. if you have done this already maybe what you need is to deploy your product app. visit this link for that . And if you want to install in windows you can follow this link

My OS is a Debian testing (8) and I have a virtualbox running ready to have a lot of virtual
machines. So I have created a Debian Stable (7) Virtual Machine that will be our server for the symfony 2 applications. in this case I’m going to use Symfony 2.3.5 the latest version available on the server. I am talking to much take a look at the image of my of my VM for more information.

Siwapp online invoicing

Wed, 18 Sep 2013 14:57:10 +0200

Siwapp is a free invoicing software. It has friendly web environment that lets you install it on a local computer and also in internet or other network server. It is not a secret that for small and medium size business one of the biggest overheads many times is money that is spent on computers software.

Linux Servers; Cost Reduction

Wed, 17 Apr 2013 11:52:03 +0200

updated on 2013-10-01

Introduction:

This document explains the main steps of the configuration of a Linux network system. With two servers for medium of small size business (in this case a Clinic). But the same project template can be applied to any other business. The main objective of this project is to create a stable solution with the best cost effectiveness balance.