Networking

Common Problems 116123

Certbot Renewal Fails on Ubuntu 26.04 LTS

🟠 High   ⏱ 5–30 min  Last verified: 17 June 2026 Affected versions: 26.04 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs […]

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How to Configure Filesystem Quotas on RHEL 10 — step-by-step RHEL 10 tutorial on Progressive Robot

How to Configure Filesystem Quotas on RHEL 10

Introduction RHEL 10 ships with a stable, security-hardened base that makes deploying configure filesystem quotas both straightforward and auditable. This tutorial covers the complete procedure for how to Configure Filesystem Quotas on RHEL 10, including dnf module streams where applicable, systemd unit management, and the firewalld rules required for network-facing services. Prerequisites Before you begin, […]

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How to Install Ruby 3.3 with rbenv on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install Ruby 3.3 with rbenv on RHEL 9

Ruby is a dynamic, object-oriented programming language best known as the language behind Ruby on Rails, the influential web framework that popularised convention-over-configuration and RESTful web applications. rbenv is the standard Ruby version manager for production servers — it allows installing and switching between multiple Ruby versions per user or per directory, without requiring root […]

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How to Configure /etc/hosts and DNS Resolution on Oracle Linux 10 — step-by-step Oracle Linux 10 tutorial on Progressive Robot

How to Configure /etc/hosts and DNS Resolution on Oracle Linux 10

Introduction This tutorial demonstrates how to Configure /etc/hosts and DNS Resolution on Oracle Linux 10 on Oracle Linux 10. It is written for administrators who want a repeatable, well-explained walkthrough that goes beyond a bare command list and explains each configuration choice. Every command is tested against a freshly registered Oracle Linux 10 system with […]

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How to Install .NET 8 SDK on RHEL 10 — step-by-step RHEL 10 tutorial on Progressive Robot

How to Install .NET 8 SDK on RHEL 10

Introduction Setting up install .net 8 sdk on a RHEL 10 server is a common task for system administrators, DevOps engineers, and site reliability engineers. This guide explains how to Install .NET 8 SDK on RHEL 10, with all the commands you need, the SELinux and firewalld considerations to keep in mind, and how to […]

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How to Set Up Two-Factor Authentication (2FA) for SSH on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Set Up WireGuard VPN on Ubuntu 26.04

WireGuard is a modern, high-performance VPN protocol built into the Linux kernel. It is faster and simpler than OpenVPN and IPsec, using state-of-the-art cryptography. This guide sets up a WireGuard VPN server on Ubuntu 26.04 LTS and connects a client. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu 26.04 LTS server with a public […]

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How to Configure OpenDKIM with Postfix on FreeBSD 15 — step-by-step FreeBSD 15 tutorial on Progressive Robot

How to Configure OpenDKIM with Postfix on FreeBSD 15

Introduction This guide explains how to Configure OpenDKIM with Postfix on FreeBSD 15 on FreeBSD 15. FreeBSD uses the pkg(8) binary package manager, rc.conf(5) for service startup configuration, and pf(4) as its primary packet filter. There is no SELinux or AppArmor — instead, FreeBSD provides the MAC (Mandatory Access Control) framework and Capsicum for fine-grained […]

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How to Set Up DRBD Block Replication on FreeBSD 15 — step-by-step FreeBSD 15 tutorial on Progressive Robot

How to Set Up DRBD Block Replication on FreeBSD 15

Introduction FreeBSD 15 is a UNIX-derived operating system renowned for its network stack performance, ZFS integration, and Jail isolation primitives. Setting up set up drbd block replication on FreeBSD 15 follows the rc.conf/service(8) paradigm rather than systemd, which means enabling a service and configuring its startup options are done differently from any Linux distribution. This […]

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How to Set Up a Git Server with Gitea on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Register a GitHub Actions Self-Hosted Runner on Ubuntu 26.04

GitHub Actions self-hosted runners allow you to run CI/CD workflows on your own hardware, giving you full control over the environment, installed tools, network access, and compute resources. This guide registers and configures a GitHub Actions self-hosted runner on Ubuntu 26.04 LTS. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu 26.04 LTS A GitHub […]

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How to Set Up Port Knocking on FreeBSD 15 — step-by-step FreeBSD 15 tutorial on Progressive Robot

How to Set Up Port Knocking on FreeBSD 15

Introduction This guide explains how to Set Up Port Knocking on FreeBSD 15 on FreeBSD 15. FreeBSD uses the pkg(8) binary package manager, rc.conf(5) for service startup configuration, and pf(4) as its primary packet filter. There is no SELinux or AppArmor — instead, FreeBSD provides the MAC (Mandatory Access Control) framework and Capsicum for fine-grained […]

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