The RULES_CHECK_THRESHOLD variable defines the number of times firewall rule
expiration times must be checked before a "deep" check is run. This allows
fwknopd to remove rules that contain a proper '_exp_<time>' even if a third party
program added them instead of fwknopd. The default value for this variable is 20,
and this typically results in this check being run every two seconds or so. To
disable this type of checking altogether, set this variable to zero.
This is a significant commit that allows fwknopd to delete expired rules
from the firewall policy regardless of whether fwknopd is tracking them.
That is, a third party program could insert rules into the fwknopd
chains (iptables for now, but this will be extended to the other
firewalls) in order to take advantage of fwknopd rule deletion.
