https://blog.aada.cat/tags/openwrt/ Recent content in Openwrt on Aada's Blog Hugo en-gb Wed, 21 Oct 2026 16:45:00 +0200 https://blog.aada.cat/posts/publishing-dhcp-lease-changes-on-mqtt/ Wed, 21 Oct 2026 16:45:00 +0200 https://blog.aada.cat/posts/publishing-dhcp-lease-changes-on-mqtt/ <p>Recently I came into the situation that I wanted to automate something based on the state of my printer. If I turn it on, a light above it should turn on so the tiny screen on it becomes readable. And when the printer turns off again, the light should turn off. To do this, I needed some way to determine when my printer turns on. Luckily it&rsquo;s very reliable at getting DHCP leases and releasing them when it turns off again. Additionally, the DHCP server that ships with OpenWRT has a flag to accept a script it should run when leases are changed<sup id="fnref:1"><a href="#fn:1" class="footnote-ref" role="doc-noteref">1</a></sup></p>