Egidio Docile

How to install Firefox Developer Edition on Linux

29 May 2020 by Egidio Docile

The “developer edition” is a special version of the Mozilla Firefox web browser tailored for web developers. It has features stabilized in nightly builds, provides experimental developer tools, and it is configured for development, so some options as remote debugging, are enabled by default.

The browser creates and uses a separate profile, so it can be used together with the standard edition of Firefox (on Linux, profiles are created inside the ~/.mozilla directory).

In this tutorial we will see how to install Firefox Developer Edition on Linux, how to add the application to our PATH, and how to create a desktop launcher for it: the instructions can be applied to any Linux distribution.

In this tutorial you will learn:

How to download and install Firefox developer edition
How to add the Firefox binary to PATH
How to create a launcher for the application

How to install Fedora/RHEL/CentOS via kickstart on an existing LUKS device

3 March 2020 by Egidio Docile

Kickstart installations let us easily script and replicate unattended or semi-unattended installations of Fedora, Red Hat Enterprise Linux or CentOS. The instructions needed to install the operating system are specified, with a dedicated syntax, inside a Kickstart file which is passed to the Anaconda installer. In this tutorial we will see how to reuse an already existing LUKS (Linux Unified Keys Setup) container when performing a Kickstart installation: this is something that cannot be achieved just with Kickstart instructions and requires some extra steps.

In this tutorial you will learn:

How to use an existing LUKS container when performing a Kickstart installation of Fedora, RHEL or CentOS
How to create and use an updates.img file to be used with the Anaconda installer.

How to schedule tasks with systemd timers in Linux

29 May 2020 by Egidio Docile

The traditional way to schedule tasks on Linux, is to use the cron daemon, specifying time intervals and
commands to be executed in crontabs.

Systemd, the relatively new init system now adopted by all the major Linux distributions, among the other things, provides the ability to schedule tasks using dedicated units, called timers. In this article we will learn how they are structured and some examples of their usage.

In this tutorial you will learn:

The basic structure of systemd timers;
How to create monotonic and realtime timers;
How to list and inspect active timers;
How to enable timers;
How to use transient timers;

How to monitor file integrity on Linux using Osquery

29 May 2020 by Egidio Docile

The basic concept involved with the use of the osquery application is the “tabular abstraction” of many aspects of the operating system, such as processes, users, etc. The data is stored in tables which can be queried using SQL syntax, directly via the osqueryi shell, or via the osqueryd daemon.

In this tutorial we will see how to install the application, how to run basic queries, and how to use FIM (File Integrity Monitoring) as part of your Linux system administration job.

In this tutorial you will learn:

How to install osquery
How to list the available tables
How to perform queries from the osqueryi shell
How to use the osqueryd daemon to monitor file integrity

How to create a selection menu using the select statement in Bash shell

3 June 2020 by Egidio Docile

We all very often use bash scripts to automatize boring and repetitive tasks. Sometimes in our scripts we need to ask
the user to perform one or more choices interactively: in this tutorial we will see how to use the Bash shell select statement to perform such operation in very few lines of code.

In this tutorial you will learn:

How to use the Bash select statement
How to customize the select menu prompt

How to parse a json file from Linux command line using jq

3 June 2020 by Egidio Docile

The JSON (JavaScript Object Notation) format is widely used to represent data structures, and is frequently used to exchange data between different layers of an application, or by the use of API calls. We probably know how to interact with json-formatted data with the most used programming languages such as parsing JSON with python, but what if we need to interact with it from the command line, or in a bash script? In this article we will see how we can accomplish such a task by using the jq utility and we will learn its basic usage.

In this tutorial you will learn:

How to install jq in the most used Linux distributions or compile it from source
How to use jq to parse json-formatted data
How to combine filters using “,” and “|”
How to use the length, keys, has and map functions

How to setup the rsync daemon on Linux

29 May 2020 by Egidio Docile

In a previous article we saw some basic examples of how to use rsync on Linux to transfer data efficiently. As we saw, to synchronize data with a remote machine we can use both a remote shell as ssh or the rsync daemon. In this article we will focus on the latter option, and we will see how to install and configure rsyncd on some of the most used Linux distributions.

In this tutorial you will learn:

How to install and configure the rsync daemon

Examples on how to use Rsync for local and remote data backups and synchonizations

29 May 2020 by Egidio Docile

Rsync is a very useful tool which allows Linux system administrators synchronize data locally or with a remote filesystem via the ssh protocol or by using the rsync daemon. Using rsync is more convenient than simply copying data, because it is able to spot and synchronize only the differences between a source and a destination. The program has options to preserve standard and extended filesystem permissions, compress the data during transfers and more. We will see the most used ones in this guide.

In this tutorial you will learn:

How to use rsync to syncronize data
How to use rsync with a remote filesystem via ssh
How to use rsync with a remote filesystem via the rsync daemon
How to exclude files from the synchronization

Hard drive shredding on Linux

29 May 2020 by Egidio Docile

When we delete a file from a filesystem, the data is not physically removed: the operating system simply marks the area previously occupied by the file, as free and makes it available to store new information. The only way to make sure data is actually removed from a device is to override it with other data. We may want to perform such operation for privacy reasons (maybe we plan to sell the device and we want to be sure the new owner cannot access our data), or maybe to prepare a device for encryption. In this tutorial we will see some tools we can use to completely wipe data on a device

In this tutorial you will learn:

How to shred data using dd
How to secure-erase files and devices using the shred utility
How to overwrite data using badblocks

How to install and configure Dropbear on Linux

29 May 2020 by Egidio Docile

The dropbear suite provides both an ssh server and a client application (dbclient), and represents a light alternative to OpenSSH. Since it has a small footprint and uses system resources very well, it is generally used on embed devices, with limited memory and processing power (e.g routers or embed devices), where optimization is a key factor. It provides a lot features, like, for example, X11 forwarding, and it is fully compatible with the OpenSSH public key authentication. In this tutorial we will see how to install it and configure it on Linux.

In this tutorial you will learn:

How to install and configure dropbear on linux
How to use the dropbearkey, dropbearconvert and dbclient utilities

How to recover deleted files with foremost on Linux

29 May 2020 by Egidio Docile

In this article we will talk about foremost, a very useful open source forensic utility which is able to recover deleted files using the technique called data carving. The utility was originally developed by the United States Air Force Office of Special Investigations, and is able to recover several file types (support for specific file types can be added by the user, via the configuration file). The program can also work on partition images produced by dd or similar tools.

In this tutorial you will learn:

How to install foremost
How to use foremost to recover deleted files
How to add support for a specific file type

How to build a docker image using a Dockerfile

29 May 2020 by Egidio Docile

Docker skills are high in demand mainly because, thanks to the Docker we can automate the deployment of applications inside so-called containers, creating tailored environments that can be easily replicated anywhere the Docker technology is supported. In this tutorial we will see how to create a Docker image from scratch, using a Dockerfile. We will learn the most important instructions we can use to customize our image, how to build the image, and how to run containers based on it.

In this tutorial you will learn:

How to create a docker image using a Dockerfile
Some of the most frequently used Dockerfile instructions
How to achieve data persistence in containers