DNS

Amazon Linux 2 — ldns — vulnerability — patch and remediation guide — diagnosis and fix on Amazon Linux 2

Amazon Linux 2 — ldns — vulnerability — patch and remediation guide

🟡 Medium   ⏱ 10–30 min  Last verified: 25 May 2026 Affected versions: Amazon Linux 2 📖 ~4 min read  •  Source: Amazon Linux advisory ALAS2-2023-2032 Related CVEs: CVE-2020-19860 Upstream summary: When ldns version 1.7.1 verifies a zone file, the ldns_rr_new_frm_str_internal function has a heap out of bounds read vulnerability. An attacker can leak information […]

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How to Configure Nginx as a Reverse Proxy for Apache2 on Debian 9 — step-by-step Debian 9 tutorial on Progressive Robot

How to Configure Nginx as a Reverse Proxy for Apache2 on Debian 9

Introduction Deploying configure nginx as a reverse proxy for apache2 on debian 9 on a Debian 9 Stretch 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 […]

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How To Acquire a Let's Encrypt Certificate Using DNS Validation with acme-dns-certbot on Ubuntu 18.04 — step-by-step Linux tutorial on Progressive Robot

How To Acquire a Let’s Encrypt Certificate Using DNS Validation with acme-dns-certbot on Ubuntu 18.04

DNS validation allows for certificate issuance requests to be verified using DNS records, rather than by serving content over HTTP. The acme-dns-certbot tool is used to connect Certbot to a third-party DNS server where the certificate validation records can be set automatically via an API when you request a certificate. The advantage of this is that you don’t need to integrate Certbot directly with your DNS provider , nor do you need to grant it unrestricted access to your full DNS configuration

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Common Problems 121629

Debian 9 GRUB Update Fails After Package Changes

🟠 High   ⏱ 5–30 min  Last verified: 20 September 2020 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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Common Problems 118485

Clock Drift and NTP Sync Problems on Ubuntu 16.04

🟡 Medium   ⏱ 5–30 min  Last verified: 20 September 2020 📖 ~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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Common Problems 118133

Ubuntu 18.04 LTS – DKMS module build fails after kernel update and drivers stop loading – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 20 September 2020 Affected versions: Ubuntu 18.04 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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Common Problems 118038

Ubuntu 18.04 LTS – kernel update leaves system stuck on old version – Fix & Prevention

🟡 Medium   ⏱ 5–30 min  Last verified: 20 September 2020 Affected versions: Ubuntu 18.04 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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Common Problems 115448

RHEL 7 Yum Locked by Another Process During Patch Window

🟡 Medium   ⏱ 5–30 min  Last verified: 20 September 2020 📖 ~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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Common Problems 112899

Windows Server 2016 – Hyper-V Replica enters critical state after network interruption – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 19 September 2020 Affected versions: Windows Server 2016 📖 ~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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Common Problems 112536

Windows Server 2019 — Routing and Remote Access service fails to start — Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 19 September 2020 Affected versions: Windows Server 2019 📖 ~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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