Re: [Qemu-discuss] How to change default network address spacces?

[Jakob Bohm]

On 1/3/2013 2:13 AM, Tony Su wrote:

Hello,

I need to change the default address spaces for virtual networks,
particularly for User Mode Networking since a network this laptop
frequently connects to recently changed its address space to the Class
A Private Network using the default subnet mask (which means that only
one networkID is supported so no other network also using the Class A
Private network address space can route.

System: x64 openSUSE 12.2
QEMU emulator version 1.1.1 (kvm-1.1.1-1.8.1

Believe the following command should have changed the address space to
a Class B Private Network, but the command tries to launch an empty
VM. Have tried running with the libvirtd service running then
restarting and also stopping the service before running the command,
and of course also with a reboot.

# qemu-kvm -net user,net=176.27.0.0/12,host=176.27.2.2,dhcpstart=176.27.0.20

All qemu-kvm (and qemu) options need to be on the same command line that
actually runs the virtual machine.

Since you are using libvirt, you should not (at your skill level) try to
change the command line directly, what you need to do is change the network
definition used by libvirt using libvirt user interfaces, as a libvirt user,
you can only use the qemu(-kvm) command line option documentation to double
check what libvirt is passing to qemu.

Unable to determine my command simply contains a syntax error, or if I
should be running a different command.

You should be using a different command altogether.  Though I am not sure
what the libvirt command is to redefine the network parameters (I cannot
find it in my own libvirt-manager GUI, but then I mostly use that for
simpler tasks these days).  Also, I believe detailed discussion of the
libvirt commands and user interface belongs to a different forum/list than
qemu-discuss, so try asking there.

Note, I have some success creating new virtual networks using
virt-manager but only if not connected to this problem physical
network. It seems that if there is a conflict with the default address
spaces, QEMU-KVM networking is rendered inoperable so I need to make a
change to the default address spaces used and make the changes
persistent.

Enjoy

Jakob
-- 
Jakob Bohm, CIO, Partner, WiseMo A/S.  http://www.wisemo.com
Transformervej 29, 2730 Herlev, Denmark.  Direct +45 31 13 16 10
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