[Cerowrt-devel] Replacing CeroWrt with OpenWrt - Routing

[Alan Jenkins]

On 13/05/15 02:19, Rich Brown wrote:
> I am working to restore the functionality of my CeroWrt 3.10.50-1
> router with an OpenWrt BB image.
>
> Things are going pretty well, but I have run into a problem. In the
> past, I frequently used two CeroWrt routers at my home: one was my
> primary, and connected via PPPoE to my DSL link; the other was the
> secondary, and used DHCP on ge00 to get an address from the LAN side
> of the primary router.
>
> My memory is that everything worked fine - I could connect to either
> router's wifi, and get to things that were on the other router's
> Wifi. (Bonjour/mDNS naming for example).
>
> With OpenWrt as my primary router and CeroWrt as the secondary, I am
> able to connect to the CeroWrt wifi and get anywhere - either the
> OpenWrt subnets or to the Internet.
>
> But connecting to the OpenWrt wifi, I cannot ping or telnet to any
> addresses on the CeroWrt... What am I missing? (This is probably not
> a deep question: I really don't understand linux routing
> configuration...)

I can start with really basic :).

AIUI CeroWrt can do this using the babel mesh routing daemon.  That 
might be what you had working.

I don't know routing daemons, but I'm quite familiar with static 
routing, so in your shoes that's probably what I'd attempt first.  It at 
least gives you an idea what's going on at the IP level.  This would 
require... as a vague checklist, and being unhelpfully vague about 
wireless...

Second router:

1) Make sure the LAN subnet (and IP address) doesn't conflict with the 
first.  I think CeroWrt already uses different addresses to OpenWrt. 
But for this example I use 192.168.16.0, netmask 255.255.255.0, and 
192.168.16.1.

Wiki explanation of netmask:
https://en.wikipedia.org/wiki/Subnetwork#Determining_the_network_prefix


2) a) Configure it with a WAN IP address that belongs to the first LAN. 
  Usually a static address, which is outside the DHCP pool.  Keep a note 
of all the static addresses you configure, to avoid conflicts.  b) Set 
default route to the first router.  OR make it a DHCP client which picks 
up the address and default route automatically.

You seem to have this part working, or CeroWrt wouldn't access the internet.


3) First router: set a static route for the subnet belonging to LAN2, 
which points at the LAN1 IP address of the second router.

You don't have this bit.

To add a separate routed wireless network on the second AP (as opposed 
to a more seamless one which allows roaming between the two APs): try 
configuring the wireless subnet adjacent to the wired one & use a single 
aggregated route for simplicity.

wireless lan: 192.168.17.0, 255.255.255.0

aggregated route for wlan + lan: 192.168.16.0/23, i.e. netmask 255.255.254.0

It could be extended to guest wireless as well.  Widen the route by 
another bit, and don't worry if you're not actually using the fourth 
subnet (192.168.19.0/24)


4) *** Make sure NAT is disabled on the second router. ***

I think you have NAT enabled on CeroWrt, because otherwise, without 
doing part 3), computers on CeroWrt network wouldn't get any packets 
_back_ from the internet.


5) Configure the firewall on the second router to accept all packets 
from the WAN interface / unknown networks.  You rely on the first router 
to do that instead.


Alan