[Assist] virt-manager isolated network

[pelzflorian (Florian Pelz)]

On Wed, Oct 24, 2018 at 07:09:54AM -0400, Jonathan Lapointe wrote:
> I set in virt-manager macvtap / bridge, so I'm able to connect easily to
> Internet with my Guest but I have to use an isolated network to be able to
> look at my own network. I follow this guide to setup my isolated network.
> 
> https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_host_configuration_and_guest_installation_guide/app_macvtap#
> 
> But it doesn't work more, I try also NAT but then I had no Internet
> access...
> 
> So far my best choice is macvtap because I have internet access but no local
> network.


Are you using NetworkManager?  Do you have dnsmasq installed?  This
way I could add a tap interface with DNS resolution like this:

    nmcli connection add type tun connection.interface-name tap0 \
     tun.mode tap tun.owner $(id -u) ipv4.method shared \
     ipv4.addresses 172.28.113.1/24

macvtap does not allow for host-to-guest connections AFAIK, so I use
tap.

I am not using virt-manager though; I do not know how to make
virt-manager use tap0.  In qemu I do

    qemu-system-x86_64 my-vm.img -m 256 -nic \
     tap,ifname=tap0,script=no,downscript=no

Then in the VM I can look up its IP address with the `ip addr` command
and can ssh into it or visit its web server.

Regards,
Florian