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Capture the Flag and War Games

If you want to acquire and maintain technical skills and you want to do it fast, then you should play in a CTF or jump into a wargame. The one thing to note is that many of these challenges attach themselves to conferences (of all sizes), and by playing in them you will likely miss the entire rest of the conference. Try not to over do it, since conferences are useful in their own way (see the rest of the career guide). Here are some of my favorite capture the flag and wargames:

There are some defense-only competitions that disguise themselves as normal CTF competitions, mainly the Collegiate Cyber Defense Challenge (CCDC) and its regional variations, and my opinion is that you should avoid them. They are exercises in system administration and frustration and will teach you little about security or anything else. They are incredibly fun to play as a Red Team though.

Atlas - Kiddie to Hacker in 5 Sleepless Nights

Psifertex - Maximum CTF: Get the Most from Capture the Flag

Chris Eagle - Organizing and Participating in CNA and CND Exercises

Mike Arpaia - Beat to 1337: Creating a Successful University Cyber Defense Organization