Reddit reviews Ethernet: The Definitive Guide: Designing and Managing Local Area Networks

If you want to pick up some Cryptography, The Code Book is a great intro.

Pragmatic Thinking and Learning is good for learning to learn.

The Pragmatic Programmer is good for project code planning and learning how to write code in a well thought out way.

Ethernet: The Definitive Guide is a good read if you want to get up to snuff on your networking, though it can be a bit dry at times.

• IT service management based on ITIL v3 2011
  
• Running Linux
  
• Ethernet: The definitive guide
  
• Learning the Bash shell
  
• CompTIA Network+
  
• Docker: Up and running
  
• TOGAF: The Open Group Architecture Framework

If you are serious about getting into networking then you need to read the following to start with:

TCP/IP fundamentals
http://www.amazon.com/gp/product/0201633469/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1

Ethernet definitive guide
http://www.amazon.com/Ethernet-Definitive-Charles-E-Spurgeon/dp/1449361846/ref=sr_1_1?s=books&ie=UTF8&qid=1397246249&sr=1-1&keywords=ethernet+the+definitive+guide

Then install GNS and create/break stuff.

Then get a CCNA under your belt, will take about 2 months of study after work to pass the exam.
http://www.amazon.com/gp/product/1118749618/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

Having the CCNA under your belt should easily get you a foot in the door.

However to understand networking you will be spending your working life studying to stay current...