Firewall

AlmaLinux 8 — nftables — vulnerability — patch and remediation guide — diagnosis and fix on AlmaLinux 8

AlmaLinux 8 — nftables — vulnerability — patch and remediation guide

🟡 Medium   ⏱ 10–30 min  Last verified: 25 May 2026 Affected versions: AlmaLinux 8 📖 ~4 min read  •  Source: AlmaLinux ALSA ALBA-2022:2004 Upstream summary: For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section. Table of contents Symptom & Impact Environment & Reproduction Root Cause […]

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How to Set Up Tripwire for File Integrity Monitoring on RHEL 8 — step-by-step RHEL 8 tutorial on Progressive Robot

How to Set Up Tripwire for File Integrity Monitoring on RHEL 8

File Integrity Monitoring (FIM) detects unauthorized changes to critical system files, binaries, and configuration directories — a key control for detecting intrusions and satisfying compliance requirements such as PCI-DSS and CIS benchmarks. Tripwire Open Source computes cryptographic hashes of monitored files at a baseline and alerts you to any subsequent modifications. This tutorial covers installing […]

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Common Problems 121623

Debian 9: UFW blocks required application ports

🟡 Medium   ⏱ 5–30 min  Last verified: 27 July 2021 Affected versions: Debian 9 📖 ~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 FreeNAS-style ZFS on FreeBSD 12 — step-by-step FreeBSD 12 tutorial on Progressive Robot

How to Set Up FreeNAS-style ZFS on FreeBSD 12

Introduction This guide explains how to Set Up FreeNAS-style ZFS on FreeBSD 12 on FreeBSD 12. 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 WireGuard VPN on FreeBSD 13 — step-by-step FreeBSD 13 tutorial on Progressive Robot

How to Set Up WireGuard VPN on FreeBSD 13 (FREEBSD-13-2)

Introduction FreeBSD 13 is a UNIX-derived operating system renowned for its network stack performance, ZFS integration, and Jail isolation primitives. Setting up set up wireguard vpn on freebsd 13 on FreeBSD 13 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 […]

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How To Set Up a Firewall Using Iptables on Ubuntu 12.04 — step-by-step Linux tutorial on Progressive Robot

How To Set Up a Firewall Using Iptables on Ubuntu 12.04

This tutorial covers setting up a very simple firewall with iptables on an ubuntu droplet. The iptables rules come from a series of options that can be combined to create each specific process. Each packet that crossing the firewall is checked by each rule in order. As soon as it matches a rule, the packet follows the associated action, otherwise it proceeds down the line. Many of the rules in the article should be copy and pastable.

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How to Configure Windows Server 2019 IPAM — step-by-step Windows Server 2019 tutorial on Progressive Robot

How to Configure Windows Server 2019 IPAM

How to Configure Windows Server 2019 IPAM IP Address Management (IPAM) in Windows Server 2019 is a built-in framework for discovering, monitoring, auditing, and managing IP address space across your network. IPAM centralizes management of DHCP and DNS servers, tracks IP address allocation and availability, and provides historical data for auditing. This guide covers installing […]

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How to Set Up Varnish Cache as a Reverse Proxy on RHEL 8 — step-by-step RHEL 8 tutorial on Progressive Robot

How to Set Up Varnish Cache as a Reverse Proxy on RHEL 8

Varnish Cache is a high-performance HTTP accelerator designed to sit in front of web servers and serve cached responses at near-wire speed, offloading PHP and database work from your backend. On RHEL 8, Varnish is packaged in the default AppStream repository, making installation straightforward. This guide shows how to install Varnish, write a VCL configuration […]

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Common Problems 125144

Oracle Linux 8 – Common Problem 018 – Diagnosis and Fix

🟡 Medium   ⏱ 5–30 min  Last verified: 24 July 2021 Affected versions: Oracle Linux 8 📖 ~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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Common Problems 118489

Ubuntu 16.04 LTS Clock Drift Breaks TLS and Kerberos

🟠 High   ⏱ 5–30 min  Last verified: 24 July 2021 Affected versions: 16.04 LTS 📖 ~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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