Re: [Qemu-discuss] need help in setting up tap networking for using qemu virtual machine

[Tony Su]

 Without actually testing your scripts,

- Have you checked you don't have a name resolution problem? Try
pinging one of Google's IP addresses instead of the name.
- Do you have a DG configured? Run the route command to verify.

Tony

On Thu, Sep 18, 2014 at 6:08 AM, Chan Kim <address@hidden> wrote:
>
> Forgot to mention that while qemu is running with RTEMS telnetd.exe,  (with 
> ETH0IP set to 48)
> from the host I get ping response from 47 and 48. But I cannot ping to 
> google.com.
> and when I type in the password at telnet, I can get in to both.
> (but couple of times got 'connection close by foreign host.' I remember)
> Thanks a lot.
> Chan Kim
>
>
>
>
> 보낸 사람 : "김찬" <address@hidden>
> 보낸 날짜 : 2014-09-18 22:00:32 ( +09:00 )
> 받는 사람 : address@hidden <address@hidden>
> 참조 :
> 제목 : need help in setting up tap networking for using qemu virtual machine
>
> Hello, everyone!
>
> It's good to have some people to ask this.. I really need a help from you and 
> this should be a basic question.
> I'm trying to run a virtual machine (using qemu-system-sparc, I added lan9220 
> emulation model inside) on my CentOS 6.4 machine.
> I've read 
> [url]http://www.linuxquestions.org/questions/linux-virtualization-and-cloud-90/centos-6-and-kvm-how-to-setup-bridged-networking-in-kvm-in-a-class-b-environment-4175433990/[/url]
>  but my case seems different and I am not sure if this previous post is 
> correct or not.
>
> My host ip is 129.254.132.47. and I want my virtual machine to be 
> 129.254.132.48. (it's class B network)
>
> I have /etc/qemu-ifup like this
>
> --------------------- start -------------------------
> #!/bin/sh
> #
> # script to bring up the tun device in QEMU in bridged mode
> # first parameter is name of tap device (e.g. tap0)
> #
> # some constants specific to the local host - change to suit your host
> #
> # guest 132.48 host 132.47 bridge 132.64
> set -x
> ETH0IP=129.254.132.47
> GATEWAY=129.254.132.1
> BROADCAST=129.254.255.255
> #
> # First take eth0 down, then bring it up with IP address 0.0.0.0
> #
> /sbin/ifdown eth0
> /sbin/ifconfig eth0 0.0.0.0 promisc up
> #
> # Bring up the tap device (name specified as first argument, by QEMU)
> #
> /usr/sbin/openvpn --mktun --dev $1 --user `id -un`
> /sbin/ifconfig $1 0.0.0.0 promisc up
> #
> # create the bridge between eth0 and the tap device
> #
> /usr/sbin/brctl addbr br0
> /usr/sbin/brctl addif br0 eth0
> /usr/sbin/brctl addif br0 $1
> #
> # only a single bridge so loops are not possible, turn off spanning tree 
> protocol
> #
> /usr/sbin/brctl stp br0 off
> #
> # Bring up the bridge with ETH0IP and add the default route
> #
> /sbin/ifconfig br0 $ETH0IP netmask 255.255.0.0 broadcast $BROADCAST
> /sbin/route add default gw $GATEWAY
> #
> # stop firewall - comment this out if you don't use Firestarter
> #
> #/sbin/service firestarter stop
> --------------------- end -------------------------
>
> and /etc/qemu-ifdown as
>
> ------------------- start --------------------------
> #!/bin/sh
> #
> # Script to bring down and delete bridge br0 when QEMU exits
> #
> # Bring down eth0 and br0
> #
> set -x
> /sbin/ifdown eth0
> /sbin/ifdown br0
> /sbin/ifconfig br0 down
> #
> # Delete the bridge
> #
> /usr/sbin/brctl delbr br0
> #
> # bring up eth0 in "normal" mode
> #
> /sbin/ifconfig eth0 -promisc
> /sbin/ifup eth0
> #
> # delete the tap device
> #
> /usr/sbin/openvpn --rmtun --dev $1
> #
> # start firewall again
> #
> #/sbin/service firestarter start
> -------------------- end --------------------------
>
> and I start my virtual machine with this command :
>
> qemu-system-sparc -M ALDEBARAN -serial stdio -kernel 
> telnetd/o-optimize/telnetd.exe -net nic -net tap,ifname=tap0
> (this makes /etc/qemu-ifup tap0 and /etc/qemu-ifdown tap0 run before and 
> after qemu run.)
>
> When I run above command, I can see the virtual machine's code is running. 
> (it's RTEMS network-demo program. telnetd.exe)
> From outside the host, I can ping to host and the guest. So I thought 
> everything is fine But I then I found something is wrong..
> When I telnet to 129.254.132.47, it is centOS as expected.
> But when I telnet to 129.254.132.48, it takes unusually long (like 10 
> seonds?) then I see the loging prompt coming from CentOS.(the host)
> I can log into it, and it's my host machine.
> (By the way, both telnetting looked hampered by something, like interfering 
> one another by wrong setting..)
>
> I can run the same telnetd program using actual board the qemu emulator is 
> emulating, and I can telnet to the board (and of course it's RTEMS). Only, 
> when using actual board, I use physical network cable between my host and the 
> board. (host 10.10.10.1 and the board 10.10.10.11)
>
> I tried setting ETH0IP to 129.254.132.47 in qemu-ifup script but it didn't 
> work.
>
> Please anyone tell me what the problem is..
>
> Kind regards,
> Chan Kim