Adjust 'ip6t-firewall-gateway' and 'ipt-firewall-gateway'. Add forward rules for game ports if aliases in use.

ipt-firewall-gateway

@@ -5528,6 +5528,13 @@ if $allow_gaming_out && ! $permit_local_net_to_inet ; then
             $ipt -A FORWARD -o $_dev -p tcp --dport $_port -m conntrack --ctstate NEW -j ACCEPT
          fi
 
+         # - Rule is needed if (local) interface aliases in use (like eth0:1)
+         # -
+         if $kernel_activate_forwarding && $local_alias_interfaces ; then
+            $ipt -A FORWARD -p tcp -o $_dev --dport $_port --tcp-flag ACK ACK -j ACCEPT
+            $ipt -A FORWARD -p tcp -i $_dev --sport $_port --tcp-flag ACK ACK -j ACCEPT
+         fi
+
       done
    done