https://hamid.goodarzi.net/Recent content on Hamidreza Goodarzi | DevOps EngineerHugoen-UShamid@goodarzi.net (Hamidreza Goodarzi)hamid@goodarzi.net (Hamidreza Goodarzi)Tue, 06 Jan 2026 00:00:00 +0000https://hamid.goodarzi.net/posts/25/05/how_to_block_ping_requests_on_a_linux_server/Sat, 03 May 2025 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/25/05/how_to_block_ping_requests_on_a_linux_server/The other day, while setting up a Linux server, I realized it was time to block Ping (ICMP requests) for security reasons. You might be wondering why disable something as basic as Ping? Well, although Ping is super useful for checking connectivity, it can also be misused in DDoS attacks or to scan networks and identify live hosts. So, in this post, I’ll walk you through a few simple methods I used to block Ping on my Linux servers across different distros.https://hamid.goodarzi.net/posts/25/02/14_essential_ssh_-security_hardening_steps_for_linux_servers/Tue, 25 Feb 2025 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/25/02/14_essential_ssh_-security_hardening_steps_for_linux_servers/Securing SSH access is crucial to prevent unauthorized logins and brute-force attacks. In this guide, I’ll share 14 essential steps that I personally use to harden SSH security on my Linux servers. 1. Disable Root Logins Logging in as root via SSH is a major security risk. Instead, I always use a regular user with sudo privileges. To disable root login, edit the SSH configuration file: sudo vim /etc/ssh/sshd_config Find and modify:https://hamid.goodarzi.net/posts/25/02/how_to_set_up_ssh_key_based_authentication_in_linux/Mon, 17 Feb 2025 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/25/02/how_to_set_up_ssh_key_based_authentication_in_linux/Tired of entering passwords every time you SSH into your server? Or maybe you just want better security? Setting up SSH key-based authentication is the best way to secure your Linux server and log in without passwords. Here’s how you can set it up in just a few steps. Why Use SSH Key-Based Authentication? Instead of relying on passwords, SSH key authentication uses a pair of cryptographic keys: Public Key → Stored on the serverhttps://hamid.goodarzi.net/posts/23/ssh-raspberry-over-usb/Sun, 17 Dec 2023 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/23/ssh-raspberry-over-usb/In this article, I will explain how to connect to a Raspberry Pi Zero via USB. Step 1: Installing Raspbian There are many tutorials available for installing Raspbian, so I won’t explain this step. After writing the Raspbian image to the memory card, without removing it, go to the boot partition and create an “ssh” file on the memory card. touch ssh Step 2: Creating Necessary Files for Raspberry Pi Connection To access the Pi Zero via SSH over USB from your device, we need to edit two files.https://hamid.goodarzi.net/posts/23/docker-image-transfer/Sat, 02 Sep 2023 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/23/docker-image-transfer/A Bash script for managing Docker images by providing functionalities for saving, loading and transferring images. Description The Docker Image Transfer script simplifies the management of Docker images. It offers the ability to save all Docker images, load images from files, and transfer images to a destination server using SCP. Usage Execute the script in a terminal to choose from the available options. ./docker-Image-transfer.sh Options The script provides the following options:https://hamid.goodarzi.net/posts/20-linux-basic-commands-you-must-know/Tue, 14 Sep 2021 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/20-linux-basic-commands-you-must-know/When using a Linux operating system, you have to use a shell, which gives you access to the operating system’s services. So learning a few basic commands will go a long way if you are considering using Linux. In this article, you’ll learn Twenty Newcomers to Linux will undoubtedly benefit from these basic Linux commands. pwd – Print working directory command in Linux cd – Linux command to navigate through directories cp – Similar usage as mv but for copying files in Linux ls – The most frequently used command in Linux to list directories mkdir – Command used to create directories in Linux mv – Move or rename files in Linux rm – Delete files or directories touch – Create blank/empty files man – Access manual pages for all Linux commands uname – Linux command to get basic information about the OS whoami – Get the active username grep – Search for a string within an output ssh – Secure Shell command in Linux ps – Display active processes wget – Direct download files from the internet sudo – Command to escalate privileges in Linux passwd – Create or update passwords for existing users grep – Search for a string within an output clear – Clear the terminal display echo – Print any text that follows the commandhttps://hamid.goodarzi.net/posts/2017/11/21/common-issue-with-panels-dealing-with-yellowish-tint-on-white-color/Tue, 21 Nov 2017 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/2017/11/21/common-issue-with-panels-dealing-with-yellowish-tint-on-white-color/One prevalent issue faced by many display panels is the tendency to exhibit a yellowish tint when displaying white colors. A solution that I have discovered involves adjusting the contrast settings to mitigate this yellowish hue. Whether you are using GNU/Linux or Windows, the following methods can help rectify the problem. Method for GNU/Linux Users For users of GNU/Linux operating systems, the xcalib utility can be employed to alleviate the yellowish tint.https://hamid.goodarzi.net/posts/2017/08/07/change-the-database-in-magento/Mon, 07 Aug 2017 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/2017/08/07/change-the-database-in-magento/Changing the database in Magento involves several steps to ensure the process is done correctly without losing data or causing site downtime. Whether you’re using Magento 1 or Magento 2, the basic steps are similar, but always ensure you’re following the version-specific documentation for any particular differences. Below is a general guide on how to change the database for a Magento site: Backup Your Current Database Before making any changes, ensure you have a complete backup of your Magento database.https://hamid.goodarzi.net/posts/2016/08/22/how-i-made-a-power-bank/Mon, 22 Aug 2016 00:00:00 +0000hamid@goodarzi.net (Hamidreza Goodarzi)https://hamid.goodarzi.net/posts/2016/08/22/how-i-made-a-power-bank/I had been wanting to get a power bank for a while. When I saw there were so many different models, I thought, “Why don’t I make one myself?” A quick search on Google showed me that there’s no need for soldering, as the ready-made board (or module) is available. The board shown in the pictures below has a micro-USB input for charging the power bank’s battery and a USB output for charging phones and other devices.