Re: Remove Virtual bridge and DNSMASQ

Laine Stump <laine@xxxxxxxxx> · Fri, 24 Apr 2015 13:00:53 -0400



    (in before Eric for this :-) Please
      don't top-post in responses on this list (or most other technical
      lists). Posting your responses in the context of the previous
      message makes it much easier for followups that want to respond to
      points from several messages at once (and also makes it easier to
      understand the discussion by reading just one of those messages).

      
      On 04/24/2015 11:08 AM, mimicafe@xxxxxxxxx wrote:

    
      HI Michal
        

        Thank you for explaining. I have this situation in a number
          of production servers where we would always use static IPs for
          the host and VMs. In such  case we have no requirement for
          NATed network in the future. And we we ever do, we can rely on
          a DHCP server within the LAN to provide IPs to the VMs.
        

        I'll look to remove both  libivirt-daemon-driver-network, libvirt-daemon-driver-network
            and dnsmasq.
      
    
    You can't remove libvirt-daemon-driver-network, as
    libvirt-daemon-driver-qemu is dependent on it (for very good
    reasons). If you try to do this, you will almost surely end up with
    a crashing libvirtd.

    
        Any further
            thought from your side?
      
    
        On 24 April 2015 at 13:12, Michal
          Privoznik <mprivozn@xxxxxxxxxx>
          wrote:

          On 24.04.2015
                12:45, mimicafe@xxxxxxxxx
              wrote:

              > I am running KVM virtualization with libvirtd
              (libvirt) 0.10.2  in bridged

              > network mode, however I still have the default
              virtual network

              > bridge/interfaces and dnsmasq on the host. What I am
              trying to understand

            > is whether or not dnsmasq and the virtual
            network (*virbr0, Vnet0 and Vnet1*)

            > still play any role. If not, can I
              remove them?

            
    You are mixing together a couple differnet (but related) things.
    virbr0 is a bridge device created for libvirt's "default" virtual
    network, and the dnsmasq instance that is running is also run by
    libvirt for that network. However, the vnet0 and vnet1 devices are
    tap devices; one of these is created for each domain interface,
    whether you use libvirt's network or you connect to a host bridge
    that you've configured yourself - you can't eliminate those devices.

    
            Yes, you can safely remove
            libvirt-daemon-config-network package. It

            should disable the default network.
        
      
    Actually that won't disable any already-installed default network.
    You'll need to do this:

    
        virsh net-destroy default

        virsh net-undefine default

    
    Once you've done this, the virbr0 device will no longer appear, and
    dnsmasq will not be run (although the binary will still be present
    on the disk).

    
           However,
            dropping dnsmasq is a bit

            harder, since libivirt-daemon-driver-network depends on it.
            We can't

            know whether you will not someday like a NATed network with
            a DHCP

            server, even though now you don't. However,

            libvirt-daemon-driver-network takes care about all the
            network types

            known to libvirt, so you can't really drop it (unless
            forcibly removing

            the package and let the libvirt just deal with it, which I'd
            discourage

            you from doing anyway).

          
    That's not going to work. There are things in the network driver
    other than just libvirt's virtual networks, and qemu isn't setup to
    deal with the network driver not being present.

    
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