Threat Landscape Briefings
Each edition covers specific attack vectors being observed in the wild — not broad categories, but actual techniques like port-knocking sequences or misconfigured iptables chains.
Newsletter & Updates
Security knowledge,
Security knowledge,
delivered direct.
Stay current with firewall configurations, threat detection patterns, and access control strategies — practical knowledge for people who manage real infrastructure.
Rule Set Walkthroughs
Step-by-step breakdowns of real firewall configurations — explaining not just the what, but why a particular nftables policy was structured that way and what alternatives were considered.
Timed Practical Exercises
Short, focused scenarios with defined constraints — diagnose a broken ACL in under 15 minutes, or audit an ingress ruleset against a given policy document. Practical skills built incrementally.
Compliance Tracking Digests
Summaries of how major frameworks — ISO 27001, NIST, CIS Controls — are being updated, with notes on which firewall-specific clauses have changed and what that means for audit readiness.
Kefalindo has been covering
network security since 2021
A consistent focus on firewall management — from perimeter rules to zero-trust segmentation — across every edition.
4 yrs
Continuous publication
Bi -weekly
Delivery cadence
6+ topics
Per edition on average
CA based
Kelowna, global readers
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No sponsored content
Firewall platforms covered pfSense, OPNsense, iptables, nftables, Palo Alto
Content depth Intermediate to advanced
Practical exercises included Most editions
Compliance frameworks tracked ISO 27001, NIST, CIS
Format Email digest, plain-text friendly
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Who reads this
For those who
For those who
manage the perimeter
Network engineers, sysadmins, and security analysts who work directly with firewall rules — not executives reading about it, but practitioners doing the work. People who know what an egress policy is and want to get better at writing them.
Occasional contributions from Florentyna Kasprzak and Václav Sorel — both with backgrounds in enterprise network security — keep the content grounded in real deployment environments.
Each edition,
structured for depth
Six recurring elements, consistent across every edition of the newsletter.
The Opening Situation
A real or reconstructed scenario — a misconfigured DMZ, an unexpected outbound connection — that frames the rest of the edition around a concrete problem.
~400 wordsAnnotated Rule Examples
Actual rule syntax with inline comments explaining each line's intent, common edge cases, and what happens when the rule is applied to asymmetric traffic.
Code-heavyCVE Watch
A shortlist of recently disclosed vulnerabilities relevant to firewall software or adjacent tooling — with notes on affected versions and what mitigation actually looks like at the rule level.
Security-focusedTool Snapshot
One tool per edition — not a feature list, but an honest look at where it works well, where it doesn't, and what kinds of environments it actually fits into based on use.
One toolCommand Line Tip
A single, specific command or flag that most people either don't know about or tend to overlook. Explained with context, not just the syntax stripped of meaning.
PracticalReader Question
One question from readers, answered in detail. Questions about real problems — log parsing confusion, rule ordering behaviour, NAT asymmetry — get priority over general curiosity.
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