How To Make Your Own Fastest Linux Computer System On Small Budget

There’s nothing more satisfying than watching a system boot up almost instantaneously when the power switch is hit. Long gone are the days of going to make yourself a brew while those spinning platters buzz and the display kicks into life, lazily dragging you into the GUI you call home.

But surely that luxury of speed is reserved for those who are willing to drop £1,000+ on a new system? Fortunately, this is not the case anymore. With advancements in technology over the last six years, and Intel’s aggressive push to keep reinvigorating its chipsets each and every generation, we’re starting to see more and more affordable budget, speed-oriented components finally making it to market.

The SSD has succeeded the hard drive with sub 10-second boot times and lightning quick file transfers. However, three years on and we’ve seen both the rise and fall of the SATA III bus. This was a standard that was supposed to last us until 2020, but now lies completely saturated, with only the ever enduring HDD still making good use of the connectivity.

Fortunately for us, workarounds have been found in the search for ever increasing performance and ever increasing speed. Utilising the PCIe bus to transfer data to and from any hard drive to the processor has proved to provide almost limitless potential when it comes to file transfer speeds – at least for the time being. And as  M.2 and U.2 PCIe SSDs have matured, so too  have their sequential read and writes, alongside a continual plummet in cost to  produce them. What this has led to is the potential to piece together a system for just over £400. 

And that’s a system we intend to walk you through today. A system including an Intel Core i5-6500 quad-core processor, one of the latest chipsets featuring the lightning fast and insanely energy efficient DDR4 memory standard, alongside a PCIe M.2 SSD. In our case, we’ve opted for one of Samsung’s OEM PM961 M.2 drives, specifically the 128GB variant.

An introduction to the Linux boot and startup processes

Understanding the Linux boot and startup processes is important to being able to both configure Linux and to resolving startup issues. This article presents an overview of the bootup sequence using the GRUB2 bootloader and the startup sequence as performed by the systemd initialization system.

In reality, there are two sequences of events that are required to boot a Linux computer and make it usable: boot and startup. The boot sequence starts when the computer is turned on, and is completed when the kernel is initialized and systemd is launched. The startup process then takes over and finishes the task of getting the Linux computer into an operational state.

Overall, the Linux boot and startup process is fairly simple to understand. It is comprised of the following steps which will be described in more detail in the following sections.

• BIOS POST
• Boot loader (GRUB2)
• Kernel initialization
• Start systemd, the parent of all processes.

Note that this article covers GRUB2 and systemd because they are the current boot loader and initialization software for most major distributions. Other software options have been used historically and are still found in some distributions.

The boot process

The boot process can be initiated in one of a couple ways. First, if power is turned off, turning on the power will begin the boot process. If the computer is already running a local user, including root or an unprivileged user, the user can programmatically initiate the boot sequence by using the GUI or command line to initiate a reboot. A reboot will first do a shutdown and then restart the computer.

BIOS POST

The first step of the Linux boot process really has nothing whatever to do with Linux. This is the hardware portion of the boot process and is the same for any operating system. When power is first applied to the computer it runs the POST (Power On Self Test) which is part of the BIOS (Basic I/O System).

When IBM designed the first PC back in 1981, BIOS was designed to initialize the hardware components. POST is the part of BIOS whose task is to ensure that the computer hardware functioned correctly. If POST fails, the computer may not be usable and so the boot process does not continue.

BIOS POST checks the basic operability of the hardware and then it issues a BIOS interrupt, INT 13H, which locates the boot sectors on any attached bootable devices. The first boot sector it finds that contains a valid boot record is loaded into RAM and control is then transferred to the code that was loaded from the boot sector.

The boot sector is really the first stage of the boot loader. There are three boot loaders used by most Linux distributions, GRUB, GRUB2, and LILO. GRUB2 is the newest and is used much more frequently these days than the other older options.

GRUB2

GRUB2 stands for "GRand Unified Bootloader, version 2" and it is now the primary bootloader for most current Linux distributions. GRUB2 is the program which makes the computer just smart enough to find the operating system kernel and load it into memory. Because it is easier to write and say GRUB than GRUB2, I may use the term GRUB in this document but I will be referring to GRUB2 unless specified otherwise.

GRUB has been designed to be compatible with the multiboot specification which allows GRUB to boot many versions of Linux and other free operating systems; it can also chain load the boot record of proprietary operating systems.

GRUB can also allow the user to choose to boot from among several different kernels for any given Linux distribution. This affords the ability to boot to a previous kernel version if an updated one fails somehow or is incompatible with an important piece of software. GRUB can be configured using the /boot/grub/grub.conf file.

GRUB1 is now considered to be legacy and has been replaced in most modern distributions with GRUB2, which is a rewrite of GRUB1. Red Hat based distros upgraded to GRUB2 around Fedora 15 and CentOS/RHEL 7. GRUB2 provides the same boot functionality as GRUB1 but GRUB2 is also a mainframe-like command-based pre-OS environment and allows more flexibility during the pre-boot phase. GRUB2 is configured with /boot/grub2/grub.cfg.

The primary function of either GRUB is to get the Linux kernel loaded into memory and running. Both versions of GRUB work essentially the same way and have the same three stages, but I will use GRUB2 for this discussion of how GRUB does its job. The configuration of GRUB or GRUB2 and the use of GRUB2 commands is outside the scope of this article.

Although GRUB2 does not officially use the stage notation for the three stages of GRUB2, it is convenient to refer to them in that way, so I will in this article.

Stage 1

As mentioned in the BIOS POST section, at the end of POST, BIOS searches the attached disks for a boot record, usually located in the Master Boot Record (MBR), it loads the first one it finds into memory and then starts execution of the boot record. The bootstrap code, i.e., GRUB2 stage 1, is very small because it must fit into the first 512-byte sector on the hard drive along with the partition table. The total amount of space allocated for the actual bootstrap code in a classic generic MBR is 446 bytes. The 446 Byte file for stage 1 is named boot.img and does not contain the partition table which is added to the boot record separately.

Because the boot record must be so small, it is also not very smart and does not understand filesystem structures. Therefore the sole purpose of stage 1 is to locate and load stage 1.5. In order to accomplish this, stage 1.5 of GRUB must be located in the space between the boot record itself and the first partition on the drive. After loading GRUB stage 1.5 into RAM, stage 1 turns control over to stage 1.5.

Stage 1.5

As mentioned above, stage 1.5 of GRUB must be located in the space between the boot record itself and the first partition on the disk drive. This space was left unused historically for technical reasons. The first partition on the hard drive begins at sector 63 and with the MBR in sector 0, that leaves 62 512-byte sectors—31,744 bytes—in which to store the core.img file which is stage 1.5 of GRUB. The core.img file is 25,389 Bytes so there is plenty of space available between the MBR and the first disk partition in which to store it.

Because of the larger amount of code that can be accommodated for stage 1.5, it can have enough code to contain a few common filesystem drivers, such as the standard EXT and other Linux filesystems, FAT, and NTFS. The GRUB2 core.img is much more complex and capable than the older GRUB1 stage 1.5. This means that stage 2 of GRUB2 can be located on a standard EXT filesystem but it cannot be located on a logical volume. So the standard location for the stage 2 files is in the /boot filesystem, specifically /boot/grub2.

Note that the /boot directory must be located on a filesystem that is supported by GRUB. Not all filesystems are. The function of stage 1.5 is to begin execution with the filesystem drivers necessary to locate the stage 2 files in the /boot filesystem and load the needed drivers.

Stage 2

All of the files for GRUB stage 2 are located in the /boot/grub2 directory and several subdirectories. GRUB2 does not have an image file like stages 1 and 2. Instead, it consists mostly of runtime kernel modules that are loaded as needed from the /boot/grub2/i386-pc directory.

The function of GRUB2 stage 2 is to locate and load a Linux kernel into RAM and turn control of the computer over to the kernel. The kernel and its associated files are located in the /boot directory. The kernel files are identifiable as they are all named starting with vmlinuz. You can list the contents of the /boot directory to see the currently installed kernels on your system.

GRUB2, like GRUB1, supports booting from one of a selection of Linux kernels. The Red Hat package manager, DNF, supports keeping multiple versions of the kernel so that if a problem occurs with the newest one, an older version of the kernel can be booted. By default, GRUB provides a pre-boot menu of the installed kernels, including a rescue option and, if configured, a recovery option.

Stage 2 of GRUB2 loads the selected kernel into memory and turns control of the computer over to the kernel.

Kernel

All of the kernels are in a self-extracting, compressed format to save space. The kernels are located in the /boot directory, along with an initial RAM disk image, and device maps of the hard drives.

After the selected kernel is loaded into memory and begins executing, it must first extract itself from the compressed version of the file before it can perform any useful work. Once the kernel has extracted itself, it loads systemd, which is the replacement for the old SysV init program, and turns control over to it.

This is the end of the boot process. At this point, the Linux kernel and systemd are running but unable to perform any productive tasks for the end user because nothing else is running.

The startup process

The startup process follows the boot process and brings the Linux computer up to an operational state in which it is usable for productive work.

systemd

systemd is the mother of all processes and it is responsible for bringing the Linux host up to a state in which productive work can be done. Some of its functions, which are far more extensive than the old init program, are to manage many aspects of a running Linux host, including mounting filesystems, and starting and managing system services required to have a productive Linux host. Any of systemd's tasks that are not related to the startup sequence are outside the scope of this article.

First, systemd mounts the filesystems as defined by /etc/fstab, including any swap files or partitions. At this point, it can access the configuration files located in /etc, including its own. It uses its configuration file, /etc/systemd/system/default.target, to determine which state or target, into which it should boot the host. The default.target file is only a symbolic link to the true target file. For a desktop workstation, this is typically going to be the graphical.target, which is equivalent to runlevel 5 in the old SystemV init. For a server, the default is more likely to be the multi-user.target which is like runlevel 3 in SystemV. The emergency.target is similar to single user mode.

Note that targets and services are systemd units.

Table 1, below, is a comparison of the systemd targets with the old SystemV startup runlevels. The systemd target aliases are provided by systemd for backward compatibility. The target aliases allow scripts—and many sysadmins like myself—to use SystemV commands like init 3 to change runlevels. Of course, the SystemV commands are forwarded to systemd for interpretation and execution.

SystemV Runlevel	systemd target	systemd target aliases	Description
	halt.target		Halts the system without powering it down.
0	poweroff.target	runlevel0.target	Halts the system and turns the power off.
S	emergency.target		Single user mode. No services are running; filesystems are not mounted. This is the most basic level of operation with only an emergency shell running on the main console for the user to interact with the system.
1	rescue.target	runlevel1.target	A base system including mounting the filesystems with only the most basic services running and a rescue shell on the main console.
2		runlevel2.target	Multiuser, without NFS but all other non-GUI services running.
3	multi-user.target	runlevel3.target	All services running but command line interface (CLI) only.
4		runlevel4.target	Unused.
5	graphical.target	runlevel5.target	multi-user with a GUI.
6	reboot.target	runlevel6.target	Reboot
	default.target		This target is always aliased with a symbolic link to either multi-user.target or graphical.target. systemd always uses the default.target to start the system. The default.target should never be aliased to halt.target, poweroff.target, or reboot.target.

Table 1: Comparison of SystemV runlevels with systemd targets and some target aliases.

Each target has a set of dependencies described in its configuration file. systemd starts the required dependencies. These dependencies are the services required to run the Linux host at a specific level of functionality. When all of the dependencies listed in the target configuration files are loaded and running, the system is running at that target level.

systemd also looks at the legacy SystemV init directories to see if any startup files exist there. If so, systemd used those as configuration files to start the services described by the files. The deprecated network service is a good example of one of those that still use SystemV startup files in Fedora.

Figure 1, below, is copied directly from the bootup man page. It shows the general sequence of events during systemd startup and the basic ordering requirements to ensure a successful startup.

The sysinit.target and basic.target targets can be considered as checkpoints in the startup process. Although systemd has as one of its design goals to start system services in parallel, there are still certain services and functional targets that must be started before other services and targets can be started. These checkpoints cannot be passed until all of the services and targets required by that checkpoint are fulfilled.

So the sysinit.target is reached when all of the units on which it depends are completed. All of those units, mounting filesystems, setting up swap files, starting udev, setting the random generator seed, initiating low-level services, and setting up cryptographic services if one or more filesystems are encrypted, must be completed, but within the sysinit.target those tasks can be performed in parallel.

The sysinit.target starts up all of the low-level services and units required for the system to be marginally functional and that are required to enable moving on to the basic.target.

local-fs-pre.target | v (various mounts and (various swap (various cryptsetup fsck services...) devices...) devices...) (various low-level (various low-level | | | services: udevd, API VFS mounts: v v v tmpfiles, random mqueue, configfs, local-fs.target swap.target cryptsetup.target seed, sysctl, ...) debugfs, ...) | | | | | \__________________|_________________ | ___________________|____________________/ \|/ v sysinit.target | ____________________________________/|\________________________________________ / | | | \ | | | | | v v | v v (various (various | (various rescue.service timers...) paths...) | sockets...) | | | | | v v v | v rescue.target timers.target paths.target | sockets.target | | | | v \_________________ | ___________________/ \|/ v basic.target | ____________________________________/| emergency.service / | | | | | | v v v v emergency.target display- (various system (various system manager.service services services) | required for | | graphical UIs) v | | multi-user.target | | | \_________________ | _________________/ \|/ v graphical.target

Figure 1: The systemd startup map.

After the sysinit.target is fulfilled, systemd next starts the basic.target, starting all of the units required to fulfill it. The basic target provides some additional functionality by starting units that re required for the next target. These include setting up things like paths to various executable directories, communication sockets, and timers.

Finally, the user-level targets, multi-user.target or graphical.target can be initialized. Notice that the multi-user.target must be reached before the graphical target dependencies can be met.

The underlined targets in Figure 1, are the usual startup targets. When one of these targets is reached, then startup has completed. If the multi-user.target is the default, then you should see a text mode login on the console. If graphical.target is the default, then you should see a graphical login; the specific GUI login screen you see will depend on the default display manager you use.

Issues

I recently had a need to change the default boot kernel on a Linux computer that used GRUB2. I found that some of the commands did not seem to work properly for me, or that I was not using them correctly. I am not yet certain which was the case, and need to do some more research.

The grub2-set-default command did not properly set the default kernel index for me in the /etc/default/grub file so that the desired alternate kernel did not boot. So I manually changed /etc/default/grub GRUB_DEFAULT=saved to GRUB_DEFAULT=2 where 2 is the index of the installed kernel I wanted to boot. Then I ran the command grub2-mkconfig > /boot/grub2/grub.cfg to create the new grub configuration file. This circumvention worked as expected and booted to the alternate kernel.

Conclusions

GRUB2 and the systemd init system are the key components in the boot and startup phases of most modern Linux distributions. Despite the fact that there has been controversy surrounding systemd especially, these two components work together smoothly to first load the kernel and then to start up all of the system services required to produce a functional Linux system.

Although I do find both GRUB2 and systemd more complex than their predecessors, they are also just as easy to learn and manage. The man pages have a great deal of information about systemd, and freedesktop.org has the complete set of systemd man pages online.

Here Is How You Can Google Search From Linux Terminal

Linux is gaining popularity day after day and it is not a completely geek stuff anymore(since we see normal people using Linux now). Every one of us uses google alot. We use Google to find answers to most simple ones to complex questions. If you are a Linux user and uses Google a lot, there is a more geeky way to search the web, since Linux users have a way to do things differently.

You can actually perform a Google search from Linux terminal. To do so, we use a utility knows as Googler. Here is how to use it.

How to Install Googler

The very first step you, would start with is by installing Googler. To install Googler, we have two methods.We are now installing it from source code and installation package. Since Googler is written in Python, make sure you have least Python 3.3 installed on your computer.

Installing from the source code:

cd /tmp

git clone https://github.com/jarun/googler.git

cd googler

sudo make install

cd auto-completion/bash/

sudo cp googler-completion.bash /etc/bash_completion.d/

Installing from the installation package

This si another way to install Googler. Here we will show you how to install Googler from installation package on Ubuntu 16.10. You can download the package from here. Type the below mentioned code in your terminal.

sudo dpkg -i googler_2.7-1_all.deb

Performing Google Search

Once you have installed Googler on your computer, it is time to perform a basic Google search from the terminal. For example, if you want to search information with the keyword named “Brad Delson”, just type the following command  and you will see the result.

googler Brad Delson

You can use “p”  and “n” to navigate to the previous page and next page of the Google Search result.

If you may want to search for the latest news about something, then just type the below mentioned command and hit enter.

googler -N Barcelona

Do You Know Why Python is Favorite Programming Language of Hackers ?

Many people learn Python specifically just for hacking and  when I first started with Python and moving from Java to Python personally felt a lot comfortable. When I needed to write a script which was not available on the internet I had to choose between Perl  and Python. Because Perl is another very popular open source interpreted programming language. When you google you will know that Python is a more popular programming language in hacking world. When compared to Perl, the Python programs are definitely clearer, simpler, easier to write and hence more maintainable and understandable.
If you are someone interested in tinkering with the information security tasks, Python is a  great language to learn because of the availability of the large number of reverse engineering and exploitation libraries for your use.


Why Python ?
Without developing some of the basic scripting skills, aspiring hacker will be condemned to realm of the script kiddie. This actually means you will be limited to using the tools that are developed by someone else, which actually decrease your probability of success and increases your probability being detected by antivirus (AV) software, intrusion detection systems (IDS), or law enforcement. With some scripting skills, you can elevate to a  professional hacker.
Python has some very important features which make it very useful for hacking, but probably most importantly, it has some pre-built libraries which provide some great functionality. Python comes with over 1,000 modules and many more are available in different other repositories.

So python is: 
Simple:  Simple is better than Complex and Complex is better than complicated.
Can be both  simple and powerful.
Free, Open Source and a High-level Language.
Object Oriented Language and Interpreted Language.
Has a rich set of libraries.

If you want to excel you skills in Python language learning Black hat Python is your best bet. 

Apart from Python, there are many other languages like C and C++ which are very useful to become an efficient hacker. Since C is a low level language and a very powerful language.. it will be an excellent addition to your profile.

Ubuntu 17.04 Beta 1 Released | New Features And Download

Ubuntu 17.04 Zesty Zapus Beta 1 release is finally here. If you’re interested, you can go ahead and download the ISO images of the participating flavors, which are, Lubuntu, Kubuntu, Xubuntu, Ubuntu Budgie, Ubuntu GNOME, Ubuntu Kylin, and Ubuntu Studio. Powered by Linux kernel 4.10, these releases feature the latest stable versions of their respective desktop environments. This release will be followed by the Final Beta release on March 23 and final release on April 13.

Ubuntu 17.04 is scheduled to release in April. Before that, official Ubuntu derivatives (or flavors) have participated in the first beta release. As a result, Ubuntu 17.04 Zesty Zapus Beta 1 has landed and it’s available for testing.

On a side note, last year in December, I wrote about the next Ubuntu release, i.e., Ubuntu 17.04, its release schedule, expected features, etc. In case you missed that, you can read it here. Also, in the upcoming days, I’ll be updating that article with more updates and new features.

Coming back to the current Ubuntu 17.01 Beta 1 release, the favors participating in the release are Lubuntu, Kubuntu, Xubuntu, Ubuntu Budgie, Ubuntu GNOME, Ubuntu Kylin, and Ubuntu Studio. Ubuntu Unity and Ubuntu MATE hasn’t participated in this release. It should be noted that it’s the first beta release of Ubuntu Budgie since it became an official Ubuntu flavor.

Read ahead to find the download links and brief information regarding the Beta 1 releases of these flavors. The Beta 1 is based on Linux kernel 4.10.

Ubuntu GNOME 17.04 Beta 1 features and download:

• Based on GNOME 3.24 Beta
• Updated GNOME Software, Calendar, other apps
• New Night Light feature
• Flatpack 0.8
• Files app Nautilus at version 3.20
• Instant messaging app Empathy removed
• New Characters map utility installed by default
• Updated set of packages

Download Ubuntu GNOME 17.04 Beta 1

Ubuntu Budgie 17.04 Beta 1 features and download:

• Latest budgie-desktop stable release v10.2.9.
• TK+3.24 applications (in beta) with GTK+3.24 window manager
• Budgie-welcome app with browser ballot screen
• AppIndicator support is now default
• Terminix is the default terminal
• This snapshot is based on Linux v4.9 kernel.

Download Ubuntu Budgie 17.04 Beta 1

Kubuntu 17.04 Beta 1 features and download:

• KDE Plasma 5.8 LTS desktop environment
• KDE Applications 16.12.1
• Multiple improvements in KDE applications

Download Kubuntu 17.04 Beta 1

Find the release notes and download links of other flavors here:

• Lubuntu 17.04 Beta 1: Download & Release notes
• Ubuntu Kylin 17.04 Beta 1: Download & Release notes
• Ubuntu Studio 17.04 Beta 1: Download & Release notes

As these releases are development versions, I won’t advise you to install them on your primary computer. Feel free to download them and perform testing on secondary machines or VMs.