Installation and Configuration of Shorewall (Firewall) using Openwrt

Install and activate a needed module:
ipkg install iptables-mod-extra
insmod ipt_LOG.o

Download and install Shorewall:
wget http://openwrt.homelinux.net/repository/shorewall_3.0.5-1_mipsel.ipk
ipkg install shorewall_3.0.5-1_mipsel.ipk

Delete the init script of the old firewall:
rm /etc/init.d/S35firewall

Copy these config files:
/etc/shorewall/interfaces
/etc/shorewall/masq
/etc/shorewall/policy
/etc/shorewall/rules
/etc/shorewall/zones

Copy these init files:
/etc/init.d/S35shorewall
/etc/init.d/S98shorewallRE
Make the init files executable:
chmod +x /etc/init.d/S35shorewall
chmod +x /etc/init.d/S98shorewallRE

Try if it works:
/etc/init.d/S35shorewall start

The second init file is a workaround, because i always had to restart the firewall after a router reboot to get it working.

Continue with macchanger.