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Connect public IPv4 addresses, IPv4 and IPv6 subnets on Hetzner servers

How can I assign VMs with public ips that I have rented out from ISP (currently Hetzner) ?

#4

You can deploy directly your VMs with IP adresses rented from Hetzner for example :

  1. assign dynamically to one VM a single public IPv4 address
  2. assign dynamically public IPv4 addresses within a subnet to many VMs
  3. assign public IPv6 within the default /64 subnet to many VMs

There is two steps for this for procedure, for all cases :

  1. Create a connexion (a bridge) with a physical interface ;
  2. Connect the VM to this bridge.

In the following example, the virtualization host is rented in a Hetzner DC. The root IPv4/IPv6 addresses are assigned on the enp2s0 interafce with the 5.9.156.152 value for IPv4 and 2a01:4f8:190:44bb::2/64 for the IPv6 public address. The default IPv6 subnet is 2a01:4f8:190:44bb::/64 with fe80::1 as default gateway.

First case : assign dynamically to one VM a single public IPv4 address

A provider like Hetzner can offer one single public IPv4 address linked with a specific MAC address generated. Only the VM using this MAC will get this IPv4 address. In the Hetzner network, a DHCP service attributes the corresponding IP address.

In my case, I obtained 5.9.156.151 linked with the 00:50:56:00:7F:E0 MAC address.

Consider that your guest is called "guest1" and that you want add an interface with the generated MAC address to obtain your new single public IP.

First, we create a L2 bridge connected to a physical NIC, the root interface enp2s0, this bridge is called hetzner1. We use the add-bridge-l2.sh to do it with ease :

./add-bridge-l2.sh hetzner1 enp2s0

In the next step, we attach a new vNIC to our VM with the MAC address from Hetzner, connected on the new bridge hetzner1 :

./add-nic.sh guest1 hetzner1 00:50:56:00:7F:E0

The device is succesfully attached :

Device attached successfully

 Interface   Type     Source   Model    MAC
-----------------------------------------------------------
 vnet0       bridge   virbr0   virtio   52:54:00:00:ff:40
 macvtap0    direct   enp2s0   virtio   00:50:56:00:7f:e0

Inside your guest, the new interface will get the public IP by DHCP.

You can use this connection for IPv6 subnets also (See below).

If you want to deploy a native VM connected on the right bridge with the correct mac address on the first interafce, you can use the define-guest-image-by-profile.sh script like this :

./define-guest-image-by-profile.sh server1 hetzner1 big centos7 00:50:56:00:7F:E0

Second case : assign dynamically public IPv4 addresses within a subnet to many VMs

In the following example, we will create a new router (bridge) that forwards the IPv4 trafic to 5.9.214.208/29 to your server from the Internet and that forwards the trafic from this subnet to the Internet. The router attributes IPv4 adresses (without network and broadcast adresses) :

./add-bridge-l3.sh hetzner2 ip4_dhcp 5.9.214.208 255.255.255.248 5.9.156.152

And you attach two new guests like guest2 and guest3 :

for x in 2 3 ; do ./add-nic.sh guest$x hetzner2 ; done

Third case : assign public IPv6 within the default /64 subnet to many VMs

To enable the default IPv6 subnet for your VMs, we simply create a L2 bridge and we attach the VMs. In this example, the root interface is enp2s0. The IPv6 range varies between 2a01:4f8:190:44bb::2 and 2a01:4f8:190:44bb:ffff:ffff:ffff:ffff.

./add-bridge-l2.sh ipv6-bridge enp2s0

We attach the guest4 VM to this bridge :

./add-nic.sh guest4 ipv6-bridge

In this case, we must configure manually the IPv6 connexion inside our VMs, for example :

ip -6 add add 2a01:4f8:190:44bb::0100/64 dev eth1
ip -6 route add default via fe80::1 dev eth1