Reddit reviews Network Security: Private Communication in a Public World (2nd Edition)

Specific to Cryptanalysis (in order):

1. start with this great tutorial on FEAL cryptanalysis
   
   
2. then try the matsano challenges
   
   
3. finally followed by Schneier's self study course on cryptanalysis.
   
   
   Good intermediate texts on cryptography/cryptology:
   
   
4. From a mathematical perspective: An Introduction to Mathematical Cryptography by Silverman et al.
   
   
5. From a provable security perspective (probably the most important to both academia and industry): Introduction to Modern Cryptography (new 2nd ed.) by Katz & Lindell
   
   
6. Serge Vaudenay's A Classical Introduction to Cryptography (it's an in between of the above 2 books).
   
   
7. Christoph Paar's Understanding Cryptography with a video course.
   
   
   Lastly, a really fantastic all around book on network security (including crypto) would be: Network Security 2nd Ed. by Kaufman and Perlman. It is a little old though but still relevant. Also has great analysis of real world protocols such as IPsec (IKE, ISAKMP), Kerberos, SSL/TLS, S/MIME, etc.

Being a "techy" isn't really useful with learning and understanding crypto. There's many cryptographers that are mathematicians who barely use computers. Cryptography is a multi-faceted discipline but the typical divide is between mathematicians and computer scientists.

So having a foundation in math & computer science is very useful.

In any case, Simon Singh's book is a good introduction. It is a pleasant read but a bit fluffy.

Although not specifically crypto, I would start with Network Security by Kaufman et al. It primarily discusses network security but gently introduces some cryptography primitives.

Another book from a mathematician perspective is this book.

Then there's joy of cryptography which is a formal treatment using a notion of provable security (a bit of a different take to Katz & Lindell Modern Cryptography), which computer scientists tend to have a boner for.

A lot of recommendations for TCP/IP Illustrated. It's a great book, but it's more concerned with host TCP/IP stacks, rather than actual network hardware. In my opinion: Interconnections: Bridges, Routers, Switches, and Internetworking Protocols, another excellent textbook which has very little intersection with the TCP/IP Illustrated series covers more relevant information for a hands-on network administrator. Steven's has a developers mindset approach, so if you're working with a host TCP/IP stack (as a developer, or tuning as a systems administrator) it might actually be more handy, but if you don't dabble much as a developer (if gethostbyname() or sockaddr_t means nothing to you then this isn't the book for you). As someone who has read many of these books and worked as a network admin for the past 7+ years, the theory and knowledge gleaned by the book is incredibly useful but not essential for a network administrator.

The aforementioned link to the book I mentioned in my opinion is wonderful and definitely worth reading. Furthermore, original RFCs make for great reading when the time is right. Also, buff up on network security and cryptography, for which I would recommend: Network Security: Private Communication in a Public World; probably the best introductory book on this matter.

Once you've mastered the basics of being a network administrator, then you should broaden your scope and maybe revisit TCP/IP Illustrated and maybe Unix Network Programming and other great books on the topic. I would also recommend picking up programming languages and the like, writing your own tools, maybe reimplementing traceroute to get an understanding of low-level network programming (and of course the traceroute algorithm). I should also mention, for a systems admin, it's essential you learn how to automate/program. Don't trust the tools that you're given, at best they're mediocre, at worst they don't work or come with support. You will need to be able to readily provide the support that you won't get from vendors, and it's always going to be an uphill battle. Less so with network administration, but it happens quite a bit as well.

Anyway, that's my advice. But when I read TCP/IP Illustrated as the essential book for a Network Administrator, it reminds me of people suggesting The Art of Computer Programming to a novice programmer. Those books are more advanced than you expect.

There are some pretty neat courses on coursera for security, not sure if there are network security specific ones. I know Stanford offers some free security classes once in a while.

In terms of books, I think my netsec course used this one - http://www.amazon.com/Network-Security-Private-Communication-Edition/dp/0130460192. (which is pretty outdated but the basics are the same).