Hostname Catcher — Hostname Whitelist for Fabric Dedicated Servers

Hostname Catcher is a lightweight Fabric mod designed for dedicated servers that lets you restrict which hostnames are accepted when players join. Configure an allowlist of hostnames or domains so only connections made through those hostnames are permitted, blocking direct IP joins and reducing unwanted traffic from server scanners. If the allowlist is left empty, the mod does not block connections but records which hostnames or IP addresses players used to connect, providing visibility into how your player base reaches the server. The mod depends only on the Fabric API. To install, stop the server, place the mod jar in your server's mods folder alongside the Fabric API, then start the server to generate the default configuration file. Edit the generated config to add allowed hostnames and restart the server for changes to take effect. When configured with entries, players joining via listed hostnames will be allowed while attempts to join using the server IP will be disconnected. When the whitelist is empty, all connections are allowed but logged with the hostname or IP used.