I am a lone IT guy working for a small company with about 20 computer users on an Internet-connected LAN. In light of all the public hacks lately, my management is looking for me to provide them with a two-page summary of what our options are to deal with potential threats to our network. For now, we are mostly concerned with external, Internet-based threats and intrusions.
I have knowledge about networking but am not a network security professional. I need a preliminary, overall, general guide book as to the resources available to someone in my position.