Firewall

Common Problems 116998

Ubuntu 22.04 LTS – SSH connection refused after reboot – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 22 October 2022 Affected versions: Ubuntu 22.04 LTS (Jammy) 📖 ~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 […]

Read more
Common Problems 114569

Postfix Cannot Send Mail Due To DNS Or Relay Policy

🟡 Medium   ⏱ 5–30 min  Last verified: 22 October 2022 📖 ~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 […]

Read more
How to Use IBM Tivoli Access Manager on IBM AIX 7.3 — step-by-step IBM AIX 7.3 tutorial on Progressive Robot

How to Use IBM Tivoli Access Manager on IBM AIX 7.3

Introduction IBM AIX 7.3 is the latest release of IBM’s enterprise-grade UNIX operating system, running on IBM Power Systems hardware. Known for its reliability, security, and performance in mission-critical environments, AIX 7.3 introduces enhanced virtualization, security hardening, and cloud integration features. This guide covers how to use ibm tivoli access manager on IBM AIX 7.3 […]

Read more
How to Configure AppArmor for Nginx on Debian 11 — step-by-step Debian 11 tutorial on Progressive Robot

How to Configure AppArmor for Nginx on Debian 11

Introduction This guide explains how to Configure AppArmor for Nginx on Debian 11 on Debian 11 Bullseye. Debian Bullseye 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 11 install with the […]

Read more
How to Configure Kerberos Authentication on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure Kerberos Authentication on RHEL 9

Kerberos is a network authentication protocol that uses symmetric-key cryptography and a trusted third party — the Key Distribution Center (KDC) — to authenticate users and services without transmitting passwords over the network. RHEL 9 ships the MIT Kerberos implementation and it integrates tightly with SSH, NFS, and other network services through GSSAPI. This tutorial […]

Read more
Common Problems 118599

Ubuntu 16.04 LTS Chrony Not Syncing Due to Firewall Policy

🟡 Medium   ⏱ 5–30 min  Last verified: 21 October 2022 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 & […]

Read more
How to Configure Trusted Execution on IBM AIX 7.3 — step-by-step IBM AIX 7.3 tutorial on Progressive Robot

How to Configure Trusted Execution on IBM AIX 7.3

Introduction IBM AIX 7.3 is the latest release of IBM’s enterprise-grade UNIX operating system, running on IBM Power Systems hardware. Known for its reliability, security, and performance in mission-critical environments, AIX 7.3 introduces enhanced virtualization, security hardening, and cloud integration features. This guide covers how to configure trusted execution on IBM AIX 7.3 with practical […]

Read more
How to Configure Gitea Self-Hosted Git Service on Debian 11 — step-by-step Debian 11 tutorial on Progressive Robot

How to Configure Gitea Self-Hosted Git Service on Debian 11

Introduction Deploying configure gitea self-hosted git service on debian 11 on a Debian 11 Bullseye machine is straightforward thanks to Debian’s policy-compliant packaging. Unlike rpm-based distributions, Debian stores configuration helpers in /etc/default/, uses update-rc.d for older init scripts, and provides dpkg-reconfigure for interactive package configuration. This tutorial stays on the systemd path throughout. Prerequisites You […]

Read more
How to Use NIS+ on IBM AIX 7.3 — step-by-step IBM AIX 7.3 tutorial on Progressive Robot

How to Use NIS+ on IBM AIX 7.3

Introduction IBM AIX 7.3 is the latest release of IBM’s enterprise-grade UNIX operating system, running on IBM Power Systems hardware. Known for its reliability, security, and performance in mission-critical environments, AIX 7.3 introduces enhanced virtualization, security hardening, and cloud integration features. This guide covers how to use nis+ on IBM AIX 7.3 with practical examples […]

Read more
How to Configure Nginx as a TCP/UDP Load Balancer on FreeBSD 12 — step-by-step FreeBSD 12 tutorial on Progressive Robot

How to Configure Nginx as a TCP/UDP Load Balancer on FreeBSD 12

Introduction This guide explains how to Configure Nginx as a TCP/UDP Load Balancer 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 […]

Read more
CHAT