Links

www.networklessons.comComplex networking topics explained in the most simple way possible
www.packet-lab.comPacket Lab - Video lessons, labs, and tests to train you on all things network related
www.firewall.cxarticles on Cisco networking, VPN security, protocol analysis, Cisco routing, switching, and VoIP technologies
www.gns3.comopen source software that simulate complex networks without having dedicated network hardware
hackingcisco.blogspot.roCisco labs CCNP/CCIE Level
ciscoiseasy.blogspot.roCisco tutorials CCNA Level
www.xmodulo.comLinux tutorials + tips & tricks