https://oypron.com/tags/security/Recent content in Security on Tech Notes - A Developer's JournalHugoen-usWed, 05 Nov 2025 09:00:00 +0000https://oypron.com/posts/kubernetes-network-policies/Wed, 05 Nov 2025 09:00:00 +0000https://oypron.com/posts/kubernetes-network-policies/<p>The first time I tried to enforce NetworkPolicy in a real cluster, I broke DNS for an entire namespace and spent the next forty minutes wondering why every pod was returning <code>i/o timeout</code>. This post is the guide I wish I had read first.</p> <h2 id="the-mental-model">The mental model</h2> <p>A NetworkPolicy is a label-selector-driven firewall rule. It only does two things:</p> <ol> <li><strong>Selects pods</strong> by label (in a single namespace).</li> <li><strong>Specifies allowed ingress, egress, or both</strong> for those pods.</li> </ol> <p>Three rules that took me too long to internalize:</p>