yannick Coffi

Founder of SNUBmonkey™ and ocularfuel.com. Linux SysAdmin and Network Security Engineer focused on hardened systems, automation, and high availability. UX/UI Designer and Photographer sharing practical Linux insights.

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issues 🛠

Issue: Logrotate Error because Parent Directory has Insecure Permissions.

tips

Who is currently connecting to your VPN server?

This is the eleventh in a series of posts featuring Protips, tips, tricks, hacks, and secrets provided by Our Team 🙊 — We want to share our top tips for the growing and thriving Linux community out there. Because sometimes you need a little help...

how to 🪄

Throw Insults when a user type the wrong password.

The SUDOERS file includes a fun hidden gem within the default sudo security policy: the “insults” feature. When enabled, this option causes sudo to throw humorous or sarcastic insults at users each time they enter an incorrect password. By default, this flag is turned off.

how to 🪄

What are Zombie processes and how get rid of them?

You may have seen zombie processes shambling around your processes list. A Zombie process is called as such because it’s already dead. You know... ZOMBIE.

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how to 🪄

How to Clear Buff/Cache in Linux?

how to 🪄

Nmap: the powerful Network Mapper.

Nmap (Network Mapper) is one of the if not the most famous free and open source scanning/ probing tools used by penetration testers and hackers for port scanning, network mapping, and, of course, vulnerability checks. Nmap is so popular, that it's been featured in the movie The Matrix. 😎

how to 🪄

How to change the default text editor in Debian.

There is a never-ending argument among Linux users over which text editor is the best when it comes to text editors. Well, after your choice is personal; I've seen folks sticking to a single editor while others use 3 to 4 at the same time. It all

how to 🪄

Systemctl daemon-reload.

A unit in Systemd is a systemd object that performs or controls a particular task or action. Systemd uses units to start/stop/manage services, organize boot process, maintain tasks and processes, create sockets, mount file-system, and initialize hardware.

tips

Run Multiple 'Cmds' at once in Linux.

This is the tenth in a series of posts featuring Protips, tips, tricks, hacks, and secrets provided by Our Team 🙊 — We want to share our top tips for the growing and thriving Linux community out there. Because sometimes you need a little help...

issues 🛠

Issue... Ubuntu netplan gateway4/6 has been deprecated!!!

Netplan is a utility for easily configuring networking on a linux system. You simply create a YAML description of the required network interfaces and what each should be configured to do. With the release of Ubuntu 22.04 (Jamie Jellyfish), NetPlan has changed !!! This option is not new. In fact,

how to 🪄

Query the systemd Journal?

journalctl is a utility for querying and displaying logs on systemd, kernel and journal on journald written by systemd-journald.service. See our previous post on Systemd journal. Working with journalctl command 1. All logs When run without any parameters, the following command will display all the logs in the

how to 🪄

How to change Sudo Session's Time Limit.

The sudo command allows us to securely perform great administrative tasks. However, after some time running a command with sudo, will prompt for a password. Because of the 15 minutes grace period; your sudo session has by default. When the 15 minutes are out, you’ll be forced to reenter

linux 🐧

APT vs Snap: What the, what the hell ...

In Linux, package managers are software tools that assist users in searching, downloading, installing, removing, and updating software packages on their system and can be accessed by either Command-Line or through a Graphical User Interface application. There is a variety of package managers to choose from, including dpkg (Debian

linux 🐧

Mail Terminology.

Client and server components There are different components involved in an email transmission from sender to recipient. MUA (Mail User Agent) Client application that allows receiving and sending emails. It can be a desktop application such as Microsoft Outlook/Thunderbird/… or web-based such as Gmail/Hotmail/… (the latter is

how to 🪄

How to install Fing on Ubuntu Debian Servers.

The Fing Command Line Interface (Fing CLI) is a standalone program that provides a set of very handy network troubleshooting tools (NIC information, scan, ping, traceroute, and so on). Installation The software has been packed using Debian (DPKG) and Read Hat (RPM) package manager. Below is the Architecture supported: • i686

tips

How to Remove/ Disable Zsh History' Commands on Linux.

This is the ninth in a series of posts featuring Protips, tips, tricks, hacks, and secrets provided by Our Team 🙊 — We want to share our top tips for the growing and thriving Linux community out there. Because sometimes you need a little help...

how to 🪄

Using the SSH Client Config File ~/.ssh/config.

Imagine you have to regularly connect to +15 remote systems over SSH. That means to remember all of the remote IP addresses, different usernames, non-standard ports, what authentication keys to use, and various command-line. Quite a big waste of time. Fortunately, SSH allows you to generate a config

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issues 🛠

Issue : “Gmail Authentication failed. Please check your username/password” Error. Also known as the “Server response: 534-5.7.14 Error”

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SSH Key-Based Authentication & how to SSH *Without a Password.

So how do you remotely connect to a Linux system? There are multiple available tools out there for remote logins but when it comes to Linux, SSH is the unicorn choice. The Secure Shell (SSH) is a protocol that /provides a secure encrypted connection between two hosts over an insecure

tips

Port xxxx-already-in-use-error- Fixed! 🛠

This is the eighth in a series of posts featuring Protips, tips, tricks, hacks, and secrets provided by Our Team 🙊 — We want to share our top tips for the growing and thriving Linux community out there. Because sometimes you need a little help...

linux 🐧

SYN-SYN-ACK and ACK 🤝

Understanding TCP Flags TCP flags are used to indicate a particular state during a TCP conversation. TCP flags can be used for troubleshooting purposes or to control how a particular connection is handled. Each of them has its own significance. They initiate connections, carry data, and tear down connections. Commonly

tips

Monitoring Web server logs (Apache, NGINX) with Netdata using Go. (Update !!!)

This is the seventh in a series of posts featuring Protips, tips, tricks, hacks, and secrets provided by Our Team 🙊 — We want to share our top tips for the growing and thriving Linux community out there. Because sometimes you need a little help...

terminal

49 Most-Used Linux Commands You Should Know.

The Linux command line is a text-based computer interface. It's also known as the Shell, Terminal, Console, CLI, or Prompt, just to name a few. Any graphical user interface (GUI) is nothing more than a graphical representation of command-line applications.

issues 🛠

Issue installing apache2 in Ubuntu 22.04: dpkg:- error processing package javascript-common (--configure):

When files in a package are modified or accidentally removed, it can damage the system. Installing the package again resolves the problem in most cases. However, using the apt install command will return an error, given that the package is already present. Here’s the error: $ sudo apt install apache2

how to 🪄

How to: Use Postfix to Outbound Email as Gmail Relay on Ubuntu - 2-step verification (Update !!!)

Postfix is a mail transfer agent (MTA) a software that implements Simple Mail Transfer Protocol (SMTP). They transport E-Mail messages from one computer to another. MTAs talk to other MTAs, and either * deliver mail locally * or hand it off for delivery to an mail delivery agent (MDA)/LDA if