This is sort of a "pie in the sky" final comment in the book. It mentions writing a built-in component (Java code) that would talk to the host computer's Ethernet driver stack and emulate an Ethernet controller IC.
I wrote a built-in OS class for the VMEmulator that accesses a sandbox in the host computer's file system so that I could write a
Jack compiler in Jack that can compile programs stored on the host computer.
An OS Intnet class that you could give a URL and that would return the web page's HTML might be a doable project, but even the simplest browser would be quite a bit of work!
--Mark