[OLSR-users] Gateway changes break connection

[Marc Quinton]

On 2/27/06, Kosta Welke <(spam-protected)> wrote:
> Hi!
>
> Short Remark: This is not about NAT problems.
>
> I've got a network setup like this:
>
> Network (non-olsr)
>   |           |
> box1        box2
>      \       /
>       +box3-+
>
> box3 is connected to box1 and box2 using a wireless link (bluetooth).
> On all 3 boxes runs olsrd on the wireless interfaces (box3 has 2
> wireless interfaces because bluetooth works that way).
> box1 and box2 both do NAT for box3.
> box3 can connect to box1, box2 and any host on the network without any
> problems, by using one of the boxes as gateway (say box1 is the gateway).
>
> Now, when the link to box1 goes down, olsr detects it pretty quickly and
> sets box2 as a new gateway. However, it seems that I need to restart
> every connection, which is logical for TCP connections, but why is that
> needed for UDP and ICMP?
>
> Example:
> I ping a host in the network. Link to box1 goes down. Ping says stuff
> like "sendmsg: Invalid argument" instead of using the new gateway.
> Restarting ping solves the problem.
>
> Is there a way to fix this behavior? I need some UDP to work and dont
> want to monitor olsr for connections breakage.

I had similar problems with my meshed network. The probleme was I was
masquerading forwarded packets.

This iptables rules before :

  $IPT -t nat -A POSTROUTING -o $WIFI -j MASQUERADE

and after, (local adresses is with netmask 10.0.0.0/8).

  $IPT -t nat -A POSTROUTING -s 10.0.0.0/8 -j MASQUERADE

Now, I think my network is very far more robust.