https://blog.kernelstub.dev/tags/phy/Recent content in PHY on Prepakis Georgios | Kernelstub | Security ResearcherHugoen-USFri, 07 Nov 2025 00:00:00 +0000https://blog.kernelstub.dev/posts/decoding-auto-negotiation-and-duplex-mismatch-at-the-phy-layer/Fri, 07 Nov 2025 00:00:00 +0000https://blog.kernelstub.dev/posts/decoding-auto-negotiation-and-duplex-mismatch-at-the-phy-layer/<h2 id="understanding-the-physical-layer-phy">Understanding the Physical Layer (PHY)</h2> <p>If you&rsquo;ve ever chased down a &ldquo;the network is slow but only sometimes and only in one direction&rdquo; ticket, there&rsquo;s a good chance the real culprit was sitting quietly at Layer 1, way below anything a <code>ping</code> or <code>traceroute</code> will show you. That&rsquo;s the world of the PHY chip, the piece of silicon on every Ethernet interface that actually puts bits onto the wire and pulls them back off again.</p>