check out the big defense contractors:

ITT General Dynamics Dyncorp KBR/Halliburton L-3 General Atomics CACI

Basically, if you want to be doing something decent, make sure you can get at least secret (not a felon, a US citizen), be vaguely professional and competent (certs are a plus, like CISA/CISSP/CCDP), and familiar with the technologies they want (it's a big crappy AD/MS network, but there's also a lot of IP stuff).