Old Engine/JAGGRAB Protocol
From RuneWiki
JAGGRAB runs on port 43595.
This protocol was used as a fallback when a resource over HTTP was not available (due to a connection timeout or 404). It downloads the necessary BZip2 archives to bootstrap the client. They are stored in main_file_cache.idx0.
The remaining model, animation, midi, and map data is loaded on demand in a separate protocol.