Larry Peterson and Bruce Davie have open-sourced their book - Computer Networks: A Systems Approach (https://github.com/SystemsApproach/book).

I am curious, what is everyone's preferred book on CN? The only one I have read is Computer Networking: A Top-Down Approach by Kurose and Ross. When learning CN for the first time, I like their approach of beginning with the application layer and moving towards the physical layer. Their figures are also quite intuitive.