[Herefordshire] Recommendations for network textbook/s?

[Matt Rhys-Roberts]

Hello,

Please could anyone recommend any good, industry standard textbooks on
computer networking, approaching the subject from a
technician/programmer's point of view?

Specifically, I'd like to know about the different layers that make up
a network, the nature of IP addresses & subnet masks, and network
security. Not too bothered about specific OS's, although I'd rather
know less about M$ and more about Unix.

Thanks in advance for any suggestions!

Matt Rhys-Roberts
Leominster