isusable

sharewall is very good

#
# Shorewall version 4 - 'isusable' sample script
#
# /etc/shorewall/isusable
#
#   This script is a companion to the 'swping' script described at 
#   http://www.shorewall.net/MultiISP.html#swping.
#
# See http://shorewall.net/shorewall_extension_scripts.htm for additional
# information.
#
###############################################################################
local status=0

[ -f /etc/shorewall/${1}.status ] && status=$(cat /etc/shorewall/${1}.status)

return $status