More obvious variable name

src/freedombone-utils-firewall

 FIREWALL_CONFIG=$HOME/${PROJECT_NAME}-firewall.cfg
 FIREWALL_DOMAINS=$HOME/${PROJECT_NAME}-firewall-domains.cfg
 FIREWALL_EIFACE=eth0
+EXTERNAL_IPV4_ADDRESS=
 
 function save_firewall_settings {
     iptables-save > /etc/firewall.conf
 }
 
 function firewall_deny_forwarding {
-    read_config_param CURRENT_IPV4_ADDRESS
-    if [ ! $CURRENT_IPV4_ADDRESS ]; then
+    read_config_param EXTERNAL_IPV4_ADDRESS
+    if [ ! $EXTERNAL_IPV4_ADDRESS ]; then
         return
     fi
     iptables -D INPUT -i ${FIREWALL_EIFACE} -m state --state NEW -p udp --dport 1194 -j ACCEPT
     iptables -D FORWARD -i tun+ -j ACCEPT
     iptables -D FORWARD -i tun+ -o ${FIREWALL_EIFACE} -m state --state RELATED,ESTABLISHED -j ACCEPT
     iptables -D FORWARD -i ${FIREWALL_EIFACE} -o tun+ -m state --state RELATED,ESTABLISHED -j ACCEPT
-    iptables -t nat -D POSTROUTING -s ${CURRENT_IPV4_ADDRESS}/24 -o ${FIREWALL_EIFACE} -j MASQUERADE
+    iptables -t nat -D POSTROUTING -s ${EXTERNAL_IPV4_ADDRESS}/24 -o ${FIREWALL_EIFACE} -j MASQUERADE
     iptables -D OUTPUT -o tun+ -j ACCEPT
     save_firewall_settings
 }
 
 function firewall_allow_forwarding {
-    curr_ipv4_address=$(get_ipv4_address)
+    curr_ipv4_address=$(get_external_ipv4_address)
     iptables -A INPUT -i ${FIREWALL_EIFACE} -m state --state NEW -p udp --dport 1194 -j ACCEPT
     iptables -A INPUT -i tun+ -j ACCEPT
     iptables -A FORWARD -i tun+ -j ACCEPT
     iptables -A FORWARD -i ${FIREWALL_EIFACE} -o tun+ -m state --state RELATED,ESTABLISHED -j ACCEPT
     iptables -t nat -A POSTROUTING -s ${curr_ipv4_address}/24 -o ${FIREWALL_EIFACE} -j MASQUERADE
     iptables -A OUTPUT -o tun+ -j ACCEPT
-    write_config_param CURRENT_IPV4_ADDRESS "$curr_ipv4_address"
+    write_config_param EXTERNAL_IPV4_ADDRESS "$curr_external_ipv4_address"
     save_firewall_settings
 }