Looking for some nice text books in the field of network security as part of my course. Our course covers mainly
Check out Practical Cryptography:
Although not confined to network security, I have also found Security Engineering: A Guide to Building Dependable Distributed Systems by Ross Anderson to be very useful for such purposes. It goes to great lengths to examine all the main technologies you will ever meet in network (and IT) security. In most cases, quite instructively, presents them with real life examples. There are also many entertaining anecdotes that underline how technologies can work or fail, sometimes spectacularly.
Moreover, it goes beyond that and examines the security environment in which these technologies will have to operate. As the title suggests the purpose of the book is not just to inform you about technologies but rather lead you to consider all aspects of a security solution. Like in the real world, the technical side is just one part of the equation. The other part is people, processes, economy, management priorities etc. Anderson's book puts all that in context and still makes a very interesting read.
And admit it..., haven't you always wanted to know what crypto systems secure nuclear weapons?
The book that i've used the most is Cryptography and Network Security by William Stallings. I would think that's a good place to start (but it's not exactly a beginner's book).
I've also heard good things about Hacking Exposed by Joel Scambray.
One caveat.. I don't have a huge experience base from with to make this conclusion, but I will say that the Stallings book has helped me in the past (but it goes pretty in-depth with cryptography in general, so it may be a bit different than what you're looking for).
I'm interested to see what other people mention... i may have to start adding to my book shelf.