Networking

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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Common Problems 122642

PF NAT Stops Working After Interface Address Change

🟠 High   ⏱ 5–30 min  Last verified: 15 May 2024 Affected versions: FreeBSD 14 📖 ~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 Set Up Alertmanager with PagerDuty and Slack Integration on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set Up Alertmanager with PagerDuty and Slack Integration on RHEL 9

Prometheus Alertmanager handles routing, deduplication, and delivery of alerts fired by Prometheus to external notification channels. On RHEL 9, integrating Alertmanager with PagerDuty and Slack allows teams to receive critical pages and contextual chat notifications from a single alert pipeline. This tutorial walks through downloading the Alertmanager binary, configuring a complete route tree, setting up […]

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Common Problems 114562

OpenSSL Policy Level Breaks Legacy TLS Connections

🟡 Medium   ⏱ 5–30 min  Last verified: 28 April 2024 📖 ~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 a Load-Balanced PostgreSQL Cluster with Patroni on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set Up a Load-Balanced PostgreSQL Cluster with Patroni on RHEL 9

PostgreSQL does not include built-in primary election or automatic failover — that is where Patroni comes in. Patroni is a Python-based template for HA PostgreSQL using a distributed configuration store (DCS) such as etcd to coordinate which node is the primary at any given time. When the primary fails, Patroni automatically elects a new primary […]

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How to Configure iptables Firewall Rules on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure iptables Firewall Rules on RHEL 9

iptables has been the standard Linux packet-filtering firewall for over two decades, and while RHEL 9 ships with nftables and firewalld as the preferred tools, iptables remains available and is widely understood by seasoned administrators. Learning iptables gives you deep insight into how Linux netfilter works and is valuable for managing legacy systems or containers […]

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How to Install Graylog for Centralised Log Management on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install Graylog for Centralised Log Management on RHEL 9

Graylog is an open-source centralised log management platform that collects, indexes, and analyses log data from across your infrastructure in one place. On RHEL 9, deploying Graylog 5.x gives operations teams powerful search, alerting, and dashboarding capabilities without relying on cloud-based log services. Graylog depends on MongoDB for metadata storage and OpenSearch (or Elasticsearch) for […]

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Common Problems 114532

RHEL 9 NetworkManager Profile Applies Wrong DNS Settings

🟡 Medium   ⏱ 5–30 min  Last verified: 15 March 2024 📖 ~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 Install and Configure cAdvisor for Container Monitoring on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install and Configure cAdvisor for Container Monitoring on RHEL 9

cAdvisor (Container Advisor) is an open-source daemon from Google that collects, aggregates, and exposes resource usage and performance metrics for every running container on a host. Unlike Docker’s built-in docker stats, cAdvisor exposes its data in Prometheus format, making it a natural fit for scraping alongside Node Exporter. This tutorial covers running cAdvisor on RHEL […]

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How to Use Podman on FreeBSD 14 — step-by-step FreeBSD 14 tutorial on Progressive Robot

How to Use Podman on FreeBSD 14

Introduction This guide explains how to Use Podman on FreeBSD 14 on FreeBSD 14. 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 privilege separation. […]

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