Try to revert to previous firewall app with SNAT support

luci-app-firewall/luasrc/model/cbi/firewall/custom.lua

@@ -0,0 +1,31 @@
+-- Copyright 2011 Jo-Philipp Wich <jow@openwrt.org>
+-- Licensed to the public under the Apache License 2.0.
+
+local fs = require "nixio.fs"
+
+local f = SimpleForm("firewall",
+	translate("Firewall - Custom Rules"),
+	translate("Custom rules allow you to execute arbitrary iptables commands \
+		which are not otherwise covered by the firewall framework. \
+		The commands are executed after each firewall restart, right after \
+		the default ruleset has been loaded."))
+
+local o = f:field(Value, "_custom")
+
+o.template = "cbi/tvalue"
+o.rows = 20
+
+function o.cfgvalue(self, section)
+	return fs.readfile("/etc/firewall.user")
+end
+
+function o.write(self, section, value)
+	value = value:gsub("\r\n?", "\n")
+	fs.writefile("/etc/firewall.user", value)
+	require("luci.sys").call("/etc/init.d/firewall restart >/dev/null 2<&1")
+	require("nixio").syslog('info', 'Restarting firewall on custom /etc/firewall.user change')
+end
+
+f.submit = translate("Restart Firewall")
+
+return f