dn42 on OpenWRT
This page gives hints on how to participate to dn42 with an OpenWRT router. It assumes Attitude Adjustment (12.09), but you can adapt it for other versions.
The intended target is a home router, acting as the default gateway for its LAN clients. The goal is to have one or more dn42 peers, announce the LAN subnet with BGP, and thus transparently provide dn42 access to the LAN clients.
This documentation assumes that the LAN is addressed in the dn42 space (
172.22.0.0/15), but it's not a big deal to add NAT if it's not.
Nothing fancy: use GRE tunnels, openvpn, anything. Don't forget to install the relevant packages with
kmod-gre for instance).
You can't manage GRE tunnels with OpenWRT, so just create them in
/etc/rc.local (and assign addresses if needed).
bird are both packaged in OpenWRT. Note that quagga is split in many packages, you probably need
Of course, you should announce the prefix of your home network.
This is needed so that OpenWRT is aware of the new interfaces (for firewall and stuff).
/etc/config/network, add entries for each dn42 interface:
config interface dn42peer1 option ifname tun-peer1 option proto none
There are two goals:
- Allowing traffic from LAN to dn42 (and maybe from dn42 to LAN too)
- If you have more than one peer, allowing traffic from dn42 to dn42 (forwarding)
Everything is done in
config zone option name dn42 option network 'dn42peer1 dn42peer2 dn42peer3' option input REJECT option output ACCEPT option forward REJECT
If you need to NAT your home network into dn42, you probably just need to add:
option masq 1
dn42 ↔ LAN forwarding
config forwarding option src lan option dest dn42
If you're confident enough, you can also forward dn42 into your LAN:
config forwarding option src dn42 option dest lan
Or you can forward only certain ports, to certain hosts, etc (standard
config rule stuff)
dn42 ↔ dn42 forwarding
This is more tricky. In theory, all you have to do is to set
option forward ACCEPT
in the definition of the zone. However, due to a bug in Attitude Adjustment (see https://dev.openwrt.org/ticket/12945), this will allow forwarding everything everywhere.
You have to use this patch: https://dev.openwrt.org/changeset/35484 (monkeypatching the relevant files in
/lib should work).
See DNS Configuration. This will use the anycast dn42 DNS server to resolve
dn42 and relevant reverse domains.