S1- Manpower (organizations)
(Note I have no affiliation with any of these groups, and list theme here because they may be of interest to like minded people for networking)
S2- Intelligence:
S6- Signals
AMRRON (American Redoubt Radio Operators Network)
Advanced Electronic Warfare and SIGINT: Association of Old Crows
(not for the technical novice)
Numbers Software for generating One Time Pads
(I can not vouch for the security of this software, but should be good against all but the most well equipped professional cryptanalyst.)
S7- Training
Mountain Guerrilla (John Mosby)