[CentOS] Block network at logoff on workstation

[David McGuffey]

I'm trying to reduce the attack surface to a home machine that is always
on and connected to the Internet.  It is running CentOS 5.4, with tight
iptables rules and sits behind a Verizon FiOS firewall/switch also
configured with tight rules.

I was wondering how to best block all network access to it when I log
off...then unblock it when I log on. Changing iptables requires root
access...as does running ifdown and ifup scripts.

I could change the permissions on ifdown and ifup and run them from the
login/logout scripts, but I'd prefer not to do that.

Any tips?

DaveM