Re: [Qemu-discuss] About how to connect from guest "10.0.2.15" to remote "192.168.1.xx"

[Mike Lovell]

On 02/14/2012 02:21 AM, Qi Zhang wrote:
> Hi There:
>
>          I'm trying to use QEMU to emulate a simple Linux Guest for
> some specific task
>          I have download/compile the Linux 3.2.5 kernel and busybox
> 1.19.4 and successfully make the guest system running after some
> simple setup.
>          Also the guest system can mount host NFS after I set the eth0
> IP to 10.0.2.15.  (mount -t nfs 10.0.2.2:/xxx/xxx /tmp)
>
>          Now the host system is also connect to a LAN (192.168.1.10),
> and there is application running on the guest system, who want to talk
> to another server on the LAN (192.168.1.8)
>          but guest (10.0.2.15) can't ping to the remote server (192.168.1.8),
>          I have manually add the default gateway as 10.0.2.2, that
> still not work.
>          Destination     Gateway         Genmask         Flags Metric
> Ref    Use Iface
>          0.0.0.0         10.0.2.2        0.0.0.0         UG    0      0
>         0 eth0
>          10.0.0.0        0.0.0.0         255.0.0.0       U     0      0
>         0 eth0
>
>          Can anybody help me to figure it out?
>          Wish the solution is not about use the tap/bridge solution,
>          I was lack of related network knowledge and the only thing I
> know is use QEMU "user net" is something similar as "NAT" option in
> virtual box,
>          though when use NAT the host can't ping to guest, but the
> guest can ping to everywhere and there is no bridge I think
>
>          BTW:
>          my host system is Ubuntu 11.10 and the command to start the QEMU is
>          "qemu-system-x86_64 -kernel arch/x86/boot/bzImage -boot d
> -append 'console=ttyS0, 115200' -nographic -net nic -net user"

if i remember correctly, the user networking doesn't support ping or 
various other ICMP messages. it uses a limited IP stack directly in the 
qemu process and doesn't support everything that the kernel's IP stack 
supports. after you set the ip address and default gateway in the guest, 
try connecting to the service you want to talk to or try putting a web 
page through wget. i frequently just use `wget http://google.com/` to 
test network connectivity when using user networking.

mike