iptables has some match extensions that will work with UTC time,
specifically the extensions --timestart and --timestop Using those you
should be able to make rules that operate all the time but block traffic
during the specified hours. The only issues there are the UTC itself
and, maybe, problems with standard time versus daylight savings time
locally.
It can also be modified to vary for certain days of the week using
--weekdays
See the manual page for iptables-extensions(8) for the details on those.
Regards,
Lars
Thanks for this suggestion Lars. I will look into iptables-extensions.
Mark