Option to disable iptable REJECT target

New UFW_DISABLE_IPTABLES_REJECT option that hacks ufw to allow the
prevention of the use of the REJECT iptables target, as this is not
available on some NAS platforms (such as the Synology).

openvpn/start.sh

@@ -92,9 +92,18 @@ function ufwAllowPortLong {
 }
 
 if [[ "${ENABLE_UFW,,}" == "true" ]]; then
+  if [[ "${UFW_DISABLE_IPTABLES_REJECT,,}" == "true" ]]; then
+    # A horrible hack to ufw to prevent it detecting the ability to limit and REJECT traffic
+    sed -i 's/return caps/return []/g' /usr/lib/python3/dist-packages/ufw/util.py
+    # force a rewrite on the enable below
+    echo "Disable and blank firewall"
+    ufw disable
+    echo "" > /etc/ufw/user.rules
+  fi
   # Enable firewall
   echo "enabling firewall"
   sed -i -e s/IPV6=yes/IPV6=no/ /etc/default/ufw
+  sed -i -e s/MANAGE_BUILTINS=no/MANAGE_BUILTINS=yes/ /etc/default/ufw
   ufw enable
 
   if [[ "${TRANSMISSION_PEER_PORT_RANDOM_ON_START,,}" == "true" ]]; then