Re: [Qemu-devel] About network bridge.

[Stefan Hajnoczi <stefanha@gmail.com>]

On Mon, Apr 22, 2013 at 09:54:02AM -0500, Yaodong Yang wrote:
> When I start my vm using virsh start vm2 or virt-manager, the vm's network is working. I can access the internet within the vm. 
> However, we I start the same vm using qemu-system-x86_64 vm2.img -m 1024. The vm can run but without internet access. I do not know the reason, can someone give me a direction?

libvirt (virsh and virt-manager) configures networking for you.

When you run QEMU manually you need to do things yourself.  If you are
running x86 guests on x86 hosts, you should probably use virsh or
virt-manager instead of manually running QEMU.  It will save a lot of
time.

If you need to test custom QEMU binaries, you can simply edit the
<emulator> domain XML tag using virsh edit.

If you really want to manually run QEMU then please read the man page.
Also see http://qemu-project.org/Documentation/Networking and then do a
web search.  There are plenty of guides to setting up networking with
QEMU.

Stefan