[Netkit.users] OpenWRT UML integrated into Netkit

[Massimo Rimondini]

Hi Saverio,

>  * I configure by hand the IP address and the default route on the
> OpenWRT virtual Machine
>  * I flush any default iptables rule on the OpenWRT virtual machine
>  * I try to ping 10.0.0.1
>   

Fine.

> If I tcpdump from OpenWRT I only see ARP requests for 10.0.0.1. So I
> see only the traffic generated from the UML OpenWRT machine.
>
> On the host machine sniffing on the tap I see the ARP requests and I
> see also the ARP reply being generated, but those answer never
> actually get back to the OpenWRT guest machine.
>
> Iptables rules on the host machine also have been checked and they look fine.
>
> Maybe I'm missing some kernel module in the UML OpenWRT guest machine ?
>   

Mmm... I don't think so. If you have configured the OpenWRT kernel with
similar parameters as the Netkit one, which I guess to be the case, no
additional module should be required. Moreover, tun/tap support only
needs to be provided by the host, because that is where a virtual
network interface needs to be set up. Tun/tap is also available inside
virtual machines only as a feature to experiment with.

> So the problem is that the traffic generated from the host machine on
> the tap interface is not heard by the guest machine... I have no idea
> how to debug deeper in this problem :(
>   

Well, this puzzles me too.
Unless this is something OpenWRT-specific, one of the few things left I
would look for is some setting in /proc/sys/net/ipv4/, maybe guest-side,
as the host did not incur any changes.
Another is the operation of vm-to-vm links: can you ping two OpenWRT
virtual machines from each other (or from a Netkit machine)? If not,
this arises a feeble suspicion on issues with the communication protocol
between UML and uml_switch. Maybe you can also check the file
~/.netkit/hubs/vhubs.log.

> Saverio
>
>   
I have corrected the citation in
http://wiki.netkit.org/index.php/Labs_Links as you have requested.

Cheers,
Massimo.


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