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.
Initial configuration
Peerings
Nothing fancy: use GRE tunnels, openvpn, anything. Don't forget to install the relevant packages with opkg (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).
BGP
quagga and bird are both packaged in OpenWRT. Note that quagga is split in many packages, you probably need quagga-bgpd, quagga-vtysh and quagga-zebra.
Interface definition
This is needed so that OpenWRT is aware of the new interfaces (for firewall and stuff).
In /etc/config/network, add entries for each dn42 interface:
config interface dn42peer1
option ifname tun-peer1
option proto none
Firewall
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 /etc/config/firewall.
Zone declaration
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
dn42 ↔ dn42 forwarding
This is more tricky.