使用 Netplan 在 Hetzner 上用于附加子网的 KVM 路由桥

我在 Hetzner 有一个运行 KVM 的专用 Ubuntu 22.04 服务器。我已将附加子网中的 IP 地址分配给来宾虚拟机。我可以按预期通过公共 IP 地址访问来宾虚拟机。

我收到了一封来自 Hetzner 的电子邮件，称我正在使用“未经允许的”MAC 地址，并威胁要阻止服务器。“不允许的”MAC 地址属于来宾虚拟机。Hetzner 支持人员表示“您必须确保您的虚拟机的 MAC 地址不会在网络设备上的公共上行链路中可见。” 有人知道如何遵守 Hetzner 的网络规则吗？这是我的配置：

1. 物理服务器

$ sudo cat /etc/netplan/01-netcfg.yaml
    ### Hetzner Online GmbH installimage
    network:
      version: 2
      renderer: networkd
      ethernets:
        enp98s0f0:
          match:
            macaddress: xx:xx:xx:xx:xx:fa
          dhcp4: no
          dhcp6: no
      bridges:
        br0:
          macaddress: xx:xx:xx:xx:xx:fa
          interfaces:
            - enp98s0f0
          dhcp4: no
          dhcp6: no
          addresses:
            - aa.bb.cc.108/32 # Physical NIC (Main IP)
            - aa.bb.cc.65/28 # First usable IP of the additional subnet
          routes:
            - to: 0.0.0.0/0
              via: aa.bb.cc.105 # Gateway for Main IP on physical NIC
              on-link: true
            - to: aa.bb.cc.64/28 # Additional subnet
              via: aa.bb.cc.65 # First usable IP of the additional subnet assigned to physical NIC above
              on-link: true
          nameservers:
            addresses:
              - 185.12.64.2
              - 185.12.64.1
          parameters:
            stp: false
            forward-delay: 0

$ cat /etc/sysctl.d/10-forwarding.conf 
net.ipv4.ip_forward=1
#net.ipv4.conf.enp98s0f0.send_redirects=0
net.ipv4.conf.all.proxy_arp=1
net.ipv4.conf.all.forwarding=1

$ cat br0.xml
<network>
    <name>br0</name>
    <forward mode='bridge'/>
    <bridge name='br0'/>
</network>

2. 访客虚拟机

$ sudo cat /etc/netplan/01-netcfg.yaml
# This is the network config written by 'subiquity'
network:
  ethernets:
    enp1s0:
      addresses:
      - aa.bb.cc.67/28 # Additional subnet
      nameservers:
        addresses:
        - 185.12.64.2
        - 185.12.64.1
        search: []
      routes:
      - to: default
        via: aa.bb.cc.65 # First usable IP of the additional subnet assigned to physical NIC
  version: 2