authentication

How to Set Up SSH Key-Based Authentication on Debian 13 — step-by-step Debian 13 tutorial on Progressive Robot

How to Set Up SSH Key-Based Authentication on Debian 13

Introduction This guide explains how to Set Up SSH Key-Based Authentication on Debian 13 on Debian 13 Trixie. Debian Trixie uses systemd for service management, nftables as the underlying packet filter (with ufw or iptables front-ends still available), and AppArmor for mandatory access control. Every command is designed for a minimal Debian 13 install with […]

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How to Set Up HTTP/3 with Nginx on Debian 13 — step-by-step Debian 13 tutorial on Progressive Robot

How to Set Up HTTP/3 with Nginx on Debian 13

Introduction Debian 13 Trixie is built around the ethos of stability and free software. Setting up set up http/3 with nginx on Trixie leverages the same proven Debian packaging system that powers millions of servers worldwide, while benefiting from the latest upstream releases included in the Trixie freeze. Follow each step carefully and the resulting […]

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How to Configure Automatic Security Updates on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure Automatic Security Updates on RHEL 9

Unpatched software is the leading cause of server compromise. The majority of publicly disclosed vulnerabilities already have patches available by the time attackers start actively exploiting them — the window between patch availability and active exploitation has shrunk from months to days. Manually patching servers is error-prone and inconsistent at scale. Automatic security updates ensure […]

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Common Problems 124168

Oracle Linux 10 – Postfix starts but mail remains deferred due to SELinux policy denial – Fix & Prevention

🟠 High   ā± 5–30 min  Last verified: 6 November 2025 Affected versions: Oracle Linux 10 šŸ“– ~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 […]

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How to Switch Default Java with alternatives on RHEL 10 — step-by-step RHEL 10 tutorial on Progressive Robot

How to Switch Default Java with alternatives on RHEL 10

Introduction Setting up switch default java with alternatives on a RHEL 10 server is a common task for system administrators, DevOps engineers, and site reliability engineers. This guide explains how to Switch Default Java with alternatives on RHEL 10, with all the commands you need, the SELinux and firewalld considerations to keep in mind, and […]

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How to Install Apache HTTP Server on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install Apache HTTP Server on RHEL 9

Apache HTTP Server (httpd) is the most historically significant web server in the history of the internet, powering billions of websites since 1995. On RHEL 9, Apache is available as httpd from the AppStream repository and integrates with SELinux, firewalld, and systemd. Apache’s module architecture makes it highly extensible: mod_rewrite for URL manipulation, mod_ssl for […]

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Common Problems 123964

DNF Metadata Download Fails Behind Corporate Proxy

🟠 High   ā± 5–30 min  Last verified: 6 November 2025 Affected versions: Oracle Linux 10 šŸ“– ~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 […]

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How to Install Nginx on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install Nginx on RHEL 9

Nginx (pronounced “engine-x”) is the most widely deployed web server in the world, powering everything from small personal websites to the largest content delivery networks. On RHEL 9, Nginx is available from the AppStream repository and integrates natively with SELinux, firewalld, and systemd. Its event-driven, non-blocking architecture means a single Nginx worker process can handle […]

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How to Install Ruby with rbenv on Oracle Linux 10 — step-by-step Oracle Linux 10 tutorial on Progressive Robot

How to Install Ruby with rbenv on Oracle Linux 10

Introduction This tutorial demonstrates how to Install Ruby with rbenv 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 the […]

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How to Harden PHP on Oracle Linux 10 — step-by-step Oracle Linux 10 tutorial on Progressive Robot

How to Harden PHP on Oracle Linux 10

Introduction This tutorial demonstrates how to Harden PHP 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 the default AppStream […]

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