WatchYourLAN is still a useful lightweight LAN scanner, but the important deployment detail is not the old CasaOS one-click tutorial—it is the application’s current host-network requirement. The upstream project scans local interfaces, records devices and history, and can notify when a new host appears.
The March 2025 forum post mainly linked to a BigBear tutorial. Today, the safest way to use that post is as a discovery pointer while taking the actual Docker requirements from the current WatchYourLAN repository.
What WatchYourLAN Actually Does
WatchYourLAN keeps a list of hosts on your local network, tracks online/offline history, can notify on newly discovered devices, and can export metrics to monitoring tools. It is not an intrusion-prevention system and it does not replace firewall rules or endpoint security.
The current WatchYourLAN repository documents the container’s required interface and persistent data path.
Host Networking Is the Critical Docker Setting
The upstream project currently says the container needs network_mode: host to scan the LAN correctly. You also need to set IFACES to the real host interface, such as eth0, enp3s0 or another interface returned by the host.
This differs from a normal web app where bridge mode plus one published port is enough. If the UI opens but device discovery is empty, verify the network mode and interface before reinstalling the container.
Persist the WatchYourLAN Database
Map a persistent host directory to /data/WatchYourLAN. Without that volume, recreating the container can erase device history and configuration. Set the timezone explicitly as well, because network events and notifications are much harder to interpret when timestamps drift.
If Docker volumes and paths are new to you, the first Docker app guide provides the basic model used by CasaOS and ZimaOS applications.
Do Not Expose the Scanner UI Carelessly
The upstream README warns that WatchYourLAN does not include built-in authentication and that host networking exposes its service on the host. Keep the web interface on a trusted LAN, restrict it with a firewall or put a real authentication layer in front of it before remote exposure.
The home-lab firewall guide explains why monitoring tools should not become an unrestricted management surface.
Bottom Line
The old BigBear tutorial remains a reasonable introduction, but current deployment should follow the upstream project: host networking, the correct interface name, a persistent data directory, an explicit timezone, and restricted access to port 8840. If scanning fails, debug those five layers before blaming CasaOS itself.
