[WireGuard] WireGuard on OpenWRT: Success

[Jason A. Donenfeld]

Not really knowing anything about OpenWRT configuration, this is what
I wound up with:

sed -i s/REJECT/DROP/g /etc/config/firewall

Then these sections are new or changed:

/etc/config/firewall:

config zone
        option name             wg
        list network            'demobox'
        option input            DROP
        option output           ACCEPT
        option forward          DROP
        option masq             1
        option mtu_fix          1

config forwarding
        option src              lan
        option dest             wg

/etc/config/network:

config interface 'wan'
        option ifname 'eth1'
        option proto 'dhcp'
        option defaultroute 0
        option customroutes '163.172.161.0/32'

config interface 'demobox'
        option proto 'wireguard'
        option private_key '...'
        option preshared_key '...'
        option addresses '.../32'

config wireguard_demobox
        option public_key '...'
        option allowed_ips '0.0.0.0/0'
        option route_allowed_ips 'enabled'
        option endpoint_host '163.172.161.0'
        option endpoint_port '...'