Network segmentation for a small company: from a flat network to zones
How to split a flat network into zones without interrupting users.
Network security, without the noise.
Every week, a short review of what actually matters and what to do about it. Always available: practical guides on networks, firewalls and defense, in plain English.
Weekly review
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Remote code execution in a popular vendor's VPN gateway
What to do. Check your software version, install the patch and restrict access to the management interface to the admin network. If no patch is available yet, take the service off the internet.
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Phishing campaign bypasses MFA by hijacking sessions
What to do. Enable phishing-resistant authentication (FIDO2) for privileged accounts, shorten session lifetimes and decide who responds to a suspicious sign-in.
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NIS2 incident reporting duties: what to check in your company
What to do. Check whether your incident reporting process meets the deadline for the early warning, and that someone knows who sends it.
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Scanning of exposed management panels is on the rise
What to do. Review what of your network is visible from the internet and close everything that doesn't need to be there.
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Open-source tool for reviewing firewall configurations
What to do. Run it on a copy of the configuration in a test environment and compare the results with a manual review of the rules.
Click an item to see what to do about it.
Guides
Material I update instead of rewriting. Each one shows the date of its last change.
Firewall hardening: 15 settings for the first hour
Settings that most often stay at their defaults and most often end in an incident.
How to read firewall logs without drowning in data
Three questions that let you review logs in 10 minutes instead of two hours.
Secure remote access without opening ports
A mesh VPN and an authenticating reverse proxy: reach your services at home without public ports.
Incident response in 60 minutes: a checklist for a small team
Who does what, and in which order, in the first hour when something looks suspicious.
Firewall rule review: dead, overly broad and duplicate rules
How to find rules in your firewall policy that should have been removed long ago.
Why this exists
onesec is a practitioner's notebook: networks, firewalls and defense, written so you can use it on Monday morning.
The weekly review picks what matters and ends every item with a concrete action. When a topic keeps coming back, it gets its own guide, which I then keep updated.
No marketing, and no jargon for its own sake.