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