comp.os.linux.security - join
Security and the GNU/Linux Operating System.
Low activity, 1738 subscribers, Usenet

comp.os.linux.answers - join
FAQs, How-To's, READMEs, etc. about Linux. (Moderated)
Low activity, 492 subscribers, Usenet

comp.os.linux.networking - join
Networking and communications under Linux.
Medium activity, 3565 subscribers, Usenet