Hi Sam,
 
You can find the rules by below command, and it looks as below:
# ebtables -t nat --list
Bridge table: nat

Bridge chain: PREROUTING, entries: 2, policy: ACCEPT
-j PREROUTING_direct
-i vnet0 -j libvirt-I-vnet0

Bridge chain: OUTPUT, entries: 1, policy: ACCEPT
-j OUTPUT_direct

Bridge chain: POSTROUTING, entries: 2, policy: ACCEPT
-j POSTROUTING_direct
-o vnet0 -j libvirt-O-vnet0

Bridge chain: PREROUTING_direct, entries: 0, policy: RETURN

Bridge chain: POSTROUTING_direct, entries: 0, policy: RETURN

Bridge chain: OUTPUT_direct, entries: 0, policy: RETURN

Bridge chain: libvirt-I-vnet0, entries: 9, policy: ACCEPT
-j I-vnet0-mac
-p IPv4 -j I-vnet0-ipv4-ip
-p IPv4 -j ACCEPT 
-p ARP -j I-vnet0-arp-mac
-p ARP -j I-vnet0-arp-ip
-p ARP -j ACCEPT 
-p 0x8035 -j I-vnet0-rarp
-p 0x835 -j ACCEPT 
-j DROP 

Bridge chain: libvirt-O-vnet0, entries: 4, policy: ACCEPT
-p IPv4 -j O-vnet0-ipv4
-p ARP -j ACCEPT 
-p 0x8035 -j O-vnet0-rarp
-j DROP 

Bridge chain: I-vnet0-mac, entries: 2, policy: ACCEPT
-s 52:54:0:3a:40:b7 -j RETURN 
-j DROP 

Bridge chain: I-vnet0-ipv4-ip, entries: 3, policy: ACCEPT
-p IPv4 --ip-src 0.0.0.0 --ip-proto udp -j RETURN 
-p IPv4 --ip-src 172.16.1.2 -j RETURN 
-j DROP 

Bridge chain: O-vnet0-ipv4, entries: 1, policy: ACCEPT
-j ACCEPT 

Bridge chain: I-vnet0-arp-mac, entries: 2, policy: ACCEPT
-p ARP --arp-mac-src 52:54:0:3a:40:b7 -j RETURN 
-j DROP 

Bridge chain: I-vnet0-arp-ip, entries: 2, policy: ACCEPT
-p ARP --arp-ip-src 172.16.1.2 -j RETURN 
-j DROP 

Bridge chain: I-vnet0-rarp, entries: 2, policy: ACCEPT
-p 0x8035 -s 52:54:0:3a:40:b7 -d Broadcast --arp-op Request_Reverse --arp-ip-src 0.0.0.0 --arp-ip-dst 0.0.0.0 --arp-mac-src 52:54:0:3a:40:b7 --arp-mac-dst 52:54:0:3a:40:b7 -j ACCEPT 
-j DROP 

Bridge chain: O-vnet0-rarp, entries: 2, policy: ACCEPT
-p 0x8035 -d Broadcast --arp-op Request_Reverse --arp-ip-src 0.0.0.0 --arp-ip-dst 0.0.0.0 --arp-mac-src 52:54:0:3a:40:b7 --arp-mac-dst 52:54:0:3a:40:b7 -j ACCEPT 
-j DROP 

For interface set as:
    <interface type='bridge'>
      <mac address='52:54:00:3a:40:b7'/>
      <source bridge='br0'/>
      <target dev='vnet0'/>
      <model type='rtl8139'/>
      <filterref filter='clean-traffic'>
        <parameter name='IP' value='172.16.1.2'/>
      </filterref>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>



-------
Best Regards,
Yalan Zhang
IRC: yalzhang


On Wed, Dec 26, 2018 at 12:28 AM fatal <fatal@mailbox.org> wrote:
Hello,

I'm recently stumbled over the libvirt network filter capabilities and
got pretty excited. Unfortunately I'm not able to get the the
"clean-traffic" filterset working. I'm using a freshly installed Debian
Stretch with libvirt, qemu and KVM.

My config snippet looks as follows:

sudo virsh edit <VM>

[...]
<interface type='bridge'>
  <mac address='52:54:00:0c:14:07'/>
  <source bridge='br0'/>
  <model type='virtio'/>
  <filterref filter='clean-traffic'>
    <parameter name='IP' value='10.10.1.2'/>
   </filterref>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
function='0x0'/>
</interface>
<interface type='bridge'>
  <mac address='52:54:00:0c:24:17'/>
  <source bridge='br1'/>
  <model type='virtio'/>
  <filterref filter='clean-traffic'>
    <parameter name='IP' value='172.16.1.2'/>
   </filterref>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
function='0x0'/>
</interface>
[...]

I restarted the VM from within the VM, did a "virsh reboot <VM>",
restarted libvirtd and even did a reboot of the host - just to be sure.
Unfortunately neither "iptables -L" nor "ebtables --list" show any
entries added by libvirt. Also omitting the "parameter name='IP'" part
didn't change anything.

There are no error messages in /var/log/syslog nor in
/var/log/libvirt/qemu/<VM>

My main references were:

https://libvirt.org/firewall.html
https://libvirt.org/formatnwfilter.html
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/virtualization_deployment_and_administration_guide/sect-virtual_networking-applying_network_filtering
https://www.berrange.com/posts/2011/10/03/guest-mac-spoofing-denial-of-service-and-preventing-it-with-libvirt-and-kvm/

Any help really would be much appreciated!

Thanks a lot!

Sam

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