This free textbook is a pretty good one on general computer networking: http://intronetworks.cs.luc.edu/current2/html/ http://intronetworks.cs.luc.edu/current2/

This free textbook is a pretty good one on general computer networking: http://intronetworks.cs.luc.edu/current2/html/ http://intronetworks.cs.luc.edu/current2/html/ I find it hard to get a good single source on Linux networking as the situation tends to change fast enough to make big efforts into documenting it out of date just as they're finished. You can learn a lot by messing around at home though if you have a couple spare machines. These days it might be a better choice to focus on software-defined networking, but so much of SDN is proprietary that it's hard to feel great about learning it.