I'm a Cisco CCNP who has moved from an ISP to a smaller company whit no Cisco equipments: using Linux boxes instead for routing and firewalling purposes.
Beside the fairly common configs of ip addressing, netmask and static routing, there are also some more complicated stuff like policy routing (a concept that I learned in the Cisco universe called PBR, Policy Based Routing).
I've tried to search for some good information about Linux networking but it seems that most of the stuff are a bit old'ish (before 2010):
Guide to IP Layer Network Administration with Linux (1)
Linux Advanced Routing & Traffic Control HOWTO (2)
In your opinion, are these still valid and enough updated or are there best study and learning material?
Thanks in advance!