Re: [Qemu-devel] Help with tun/tap with qemu

["Jesus M. Salvo Jr." <jesus.salvo@migasia.com>]

Antony T Curtis wrote:

>On Tue, 2004-08-10 at 16:50, Bartosz Fabianowski wrote:
>  
>
>>>So I am trying TUN/TAP.  The guest and host OS can ping each other.
>>>However, the guest OS cannot ping any other host
>>>      
>>>
>>If the setup on Linux is any similar to that on FreeBSD (and I am sure 
>>it is), the problem probably is routing. The guest and host are on 
>>different networks. So, you need to tell your host to forward packets to 
>>and from the guest's network. You didn't have that problem in slirp, 
>>because slirp bridges between the two networks for you, it implicitly 
>>does the forwarding.
>>
>>Unfortunately, I can't tell you how to add the route under Linux due to 
>>my lack of experience with that platform.
>>
>>- Bartosz
>>    
>>
>
>When I am using TAP on FreeBSD, I use ng_bridge so the guest is on the
>same network as the host.
>
>Info for configuring ng_bridge is in
>/usr/share/examples/netgraph/ether.bridge
>
>  
>
OK, I have now setup a bridge on linux as follows.
On the host OS, I have the following script and ran it as root:

#!/bin/sh
/usr/sbin/brctl addbr br0
/sbin/ifconfig eth2 0.0.0.0 promisc up
/sbin/ifconfig tap0 0.0.0.0 promisc up
/sbin/ifconfig br0 192.168.0.199 netmask 255.255.255.0 broadcast 
192.168.0.255 up
/usr/sbin/brctl stp br0 off
/usr/sbin/brctl setfd br0 1
/usr/sbin/brctl sethello br0 1
/usr/sbin/brctl addif br0 eth2
/usr/sbin/brctl addif br0 tap0
/sbin/route add default gw 192.168.0.1

I can confirm that the host still has network connectivity using the bridge.

Now the question is, what to do on the qemu side ??
If I just run qemu as normal, qemu says:

    Connected to host network interface: tun0

... because of the /etc/qemu-ifup script on the host OS ( and of course, 
tun0 has an IP address )
Shouldn't qemu use tap0 as per the bridge configuration on the host OS ?
If so, how do u tell qemu to use tap0 instead of tun0 ?
Or should I change the bridge configuration to use tun0 instead of tap0 
on the host OS ?