Hetzner 2 Public IPs - Additional IP not working

[mrEckendonk]

Hello,

This hetzner machine is driving me nuts for over the last 2 weeks, spend many hours to get the network to work.

1 IP is for the Proxmox UI
1 IP for the VM/NAT
2 IPv6 for some other

I already added support from hetzner, they told the IP's where fine, but I tried so much different setups that I have my doubts and need someone to verify my config.

Here is my /etc/network/interface, let me know if there is something wrong that my 2 adidtional IP won't come up. I hope someone can help me with this or any other setup that might work better.

Thanks!

# network interface settings; autogenerated
# Please do NOT modify this file directly, unless you know what
# you're doing.
#
# If you want to manage parts of the network configuration manually,
# please utilize the 'source' or 'source-directory' directives to do
# so.
# PVE will preserve these directives, but will NOT read its network
# configuration from sourced files, so do not attempt to move any of
# the PVE managed interfaces into external files!

auto lo
iface lo inet loopback

auto enp4s0
iface enp4s0 inet static
        address 85.xxx.xxx.121/32
        gateway 85.xxx.xxx.97
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up echo 1 > /proc/sys/net/ipv4/conf/enp4s0/proxy_arp

iface enp4s0 inet6 static
        address 2a01:4f8:xx:xxx::10/128
        gateway fe80::1

auto vmbr0
iface vmbr0 inet static
        address 10.10.10.1/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        post-up iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o enp4s0 -j MASQUERADE
        post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o enp4s0 -j MASQUERADE

iface vmbr0 inet6 static
        address 2a01:4f8:xx:xxx::1/64

auto vmbr1
iface vmbr1 inet static
        address 85.xxx.xxx.121/32
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        post-up ip route add 88.xxx.xxx.38/32 dev vmbr1

iface vmbr1 inet6 static
        address 2a01:4f8:xx:xxxx::2/64
        gateway fe80::1

auto vmbr2
iface vmbr2 inet static
        address 10.0.20.254/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0
#dmz

auto vmbr3
iface vmbr3 inet manual
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094
#guest lan

source /etc/network/interfaces.d/*

 

[Onslow]

Welcome! Possibly related? https://forum.proxmox.com/threads/hetzner-setup-dealing-with-mac-addresses.150887/ |||| https://forum.proxmox.com/threads/correct-settings-for-hetzner-and-allowed-mac-addresses.150660/
In general: https://forum.proxmox.com/tags/hetzner/

 

[readyspace]

Hello,

This hetzner machine is driving me nuts for over the last 2 weeks, spend many hours to get the network to work.

1 IP is for the Proxmox UI
1 IP for the VM/NAT
2 IPv6 for some other

I already added support from hetzner, they told the IP's where fine, but I tried so much different setups that I have my doubts and need someone to verify my config.

Here is my /etc/network/interface, let me know if there is something wrong that my 2 adidtional IP won't come up. I hope someone can help me with this or any other setup that might work better.

Thanks!

# network interface settings; autogenerated
# Please do NOT modify this file directly, unless you know what
# you're doing.
#
# If you want to manage parts of the network configuration manually,
# please utilize the 'source' or 'source-directory' directives to do
# so.
# PVE will preserve these directives, but will NOT read its network
# configuration from sourced files, so do not attempt to move any of
# the PVE managed interfaces into external files!

auto lo
iface lo inet loopback

auto enp4s0
iface enp4s0 inet static
        address 85.xxx.xxx.121/32
        gateway 85.xxx.xxx.97
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up echo 1 > /proc/sys/net/ipv4/conf/enp4s0/proxy_arp

iface enp4s0 inet6 static
        address 2a01:4f8:xx:xxx::10/128
        gateway fe80::1

auto vmbr0
iface vmbr0 inet static
        address 10.10.10.1/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        post-up iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o enp4s0 -j MASQUERADE
        post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o enp4s0 -j MASQUERADE

iface vmbr0 inet6 static
        address 2a01:4f8:xx:xxx::1/64

auto vmbr1
iface vmbr1 inet static
        address 85.xxx.xxx.121/32
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        post-up ip route add 88.xxx.xxx.38/32 dev vmbr1

iface vmbr1 inet6 static
        address 2a01:4f8:xx:xxxx::2/64
        gateway fe80::1

auto vmbr2
iface vmbr2 inet static
        address 10.0.20.254/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0
#dmz

auto vmbr3
iface vmbr3 inet manual
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094
#guest lan

source /etc/network/interfaces.d/*

Hi, it seems to be a Hetzner dedicated server networking issue — very common when users try to add multiple public IPv4 and IPv6 addresses.

Some things to note : Looks like you’re assigning the same public IP to both enp4s0 and vmbr1, which confuses routing — only the bridge should hold it.

Also, with Hetzner’s /32 setup, you need a static route for the gateway before declaring it.

Move your IPv6 gateway back to enp4s0, not vmbr1, and disable proxy_arp there.

Each extra IP should be routed via your main address rather than directly configured with its own gateway.

Hope this helps.