Mail Services

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

How to Install ClamAV Antivirus on RHEL 9

ClamAV is an open-source antivirus engine widely used on Linux servers to detect malware in files destined for Windows users — such as email attachments, uploaded documents, and shared network storage. While Linux systems are largely immune to the Windows malware that ClamAV detects, running it is a responsible practice wherever Linux servers act as […]

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How to Use OpenSSL to Generate and Manage SSL Certificates on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Use OpenSSL to Generate and Manage SSL Certificates on RHEL 9

OpenSSL is the most widely used toolkit for working with SSL/TLS certificates on Linux systems. On RHEL 9, it provides everything you need to generate private keys, create certificate signing requests (CSRs), sign certificates using your own certificate authority, and convert between certificate formats. Understanding OpenSSL is essential for any sysadmin managing secure services. This […]

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How to Configure a Static IP Address with NetworkManager on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure a Static IP Address with NetworkManager on RHEL 9

NetworkManager is the default network management service on RHEL 9, and it provides a powerful command-line tool called nmcli for configuring network interfaces. Assigning a static IP address is a common requirement for servers that need a predictable, stable address on the network. This tutorial walks through every method available on RHEL 9 to configure […]

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How to Install and Configure Postfix Mail Server on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install and Configure Postfix Mail Server on RHEL 9

Postfix is a high-performance, open-source Mail Transfer Agent (MTA) that handles the sending and receiving of email over SMTP. It is the default MTA on many Linux distributions and integrates cleanly with the rest of the RHEL 9 mail stack, including Dovecot for IMAP delivery and OpenDKIM for email authentication. This tutorial covers installing Postfix, […]

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How to Configure Postfix Mail Server on Debian 12 — step-by-step Debian 12 tutorial on Progressive Robot

How to Configure Postfix Mail Server on Debian 12

Introduction This guide explains how to Configure Postfix Mail Server on Debian 12 on Debian 12 Bookworm. Debian Bookworm 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 12 install with the […]

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Common Problems 124637

Oracle Linux 9 – Common Problem 018 – Diagnosis and Fix

🟡 Medium   ⏱ 5–30 min  Last verified: 21 October 2023 Affected versions: Oracle Linux 9 📖 ~3 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 Configure OpenDKIM with Postfix on Debian 12 — step-by-step Debian 12 tutorial on Progressive Robot

How to Configure OpenDKIM with Postfix on Debian 12

Introduction This guide explains how to Configure OpenDKIM with Postfix on Debian 12 on Debian 12 Bookworm. Debian Bookworm 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 12 install with the […]

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Common Problems 115540

Postfix Service Inactive After Package Changes

🟡 Medium   ⏱ 5–30 min  Last verified: 20 August 2023 📖 ~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 References & Further […]

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How to Set Up System Center Operations Manager (SCOM) on Windows Server 2022 — step-by-step Windows Server 2022 tutorial on Progressive Robot

How to Set Up System Center Operations Manager (SCOM) on Windows Server 2022

SCOM Architecture and Components System Center Operations Manager (SCOM) is Microsoft’s enterprise monitoring platform, part of the System Center suite. It provides agent-based and agentless monitoring of Windows servers, network devices, Linux systems, and cloud workloads. Understanding the architecture before deployment is essential for sizing hardware correctly and planning for high availability. The core components […]

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How to Configure Windows Server 2022 Software Load Balancer — step-by-step Windows Server 2022 tutorial on Progressive Robot

How to Configure Windows Server 2022 Software Load Balancer

Introduction to Monitoring Windows Server 2022 with Prometheus Prometheus is a pull-based metrics system that scrapes HTTP endpoints at configured intervals and stores time-series data for querying and alerting. The windows_exporter (formerly wmi_exporter) is the standard Prometheus exporter for Windows Server, exposing hundreds of metrics covering CPU, memory, disk, network, IIS, services, and more. This […]

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