OpenWRT Stealth Firewall

root@OpenWrt:~# vi /etc/config/firewall

config defaults
option syn_flood '1'
option input 'DROP'
option output 'DROP'
option forward 'DROP'

config zone
option name 'lan'
list network 'lan'
option input 'ACCEPT'
option output 'ACCEPT'
option forward 'ACCEPT'

config zone
option name 'wan'
list network 'wan'
list network 'wan6'
option input 'DROP'
option output 'ACCEPT'
option forward 'DROP'
option masq '1'
option mtu_fix '1'

config forwarding
option src 'lan'
option dest 'wan'