Firewall

Common Problems 118046

Ubuntu 18.04 LTS – UFW policy change blocks SSH and remote administration – Fix & Prevention

🔴 Critical   ⏱ 5–30 min  Last verified: 20 May 2026 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 […]

Read more
Common Problems 115538

RHEL 7 firewalld Rich Rule Order Breaks DNAT

🟡 Medium   ⏱ 5–30 min  Last verified: 20 May 2026 📖 ~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
Common Problems 115528

RHEL 7 service mariadb Starts then Immediately Stops

🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026 📖 ~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
Common Problems 119062

Ubuntu 14.04 LTS UFW rule change accidentally blocks SSH

🔴 Critical   ⏱ 5–30 min  Last verified: 19 May 2026 Affected versions: 14.04 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
Common Problems 124090

Oracle Linux 10 – NetworkManager connection drops caused by incorrect MTU on VLAN – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026 Affected versions: Oracle Linux 10 📖 ~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
Common Problems 114030

RHEL 10 – NetworkManager connection drops caused by incorrect MTU on VLAN – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026 Affected versions: RHEL 10.0 RHEL 10.1 📖 ~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 124081

Oracle Linux 10 – chronyd not syncing time due to firewall and SELinux policy mismatch – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026 Affected versions: Oracle Linux 10 📖 ~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
Common Problems 114020

RHEL 10 – chronyd not syncing time due to firewall and SELinux policy mismatch – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026 Affected versions: RHEL 10.0 RHEL 10.1 📖 ~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 114519

Disk Fills Quickly Because Journald Logs Grow Unbounded

🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026 📖 ~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
Common Problems 115518

RHEL 7 NTP Drift Causes Yum TLS Certificate Errors

🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026 📖 ~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
CHAT