Unlike a Promox Routed Networking setup, Proxmox Bridged networking requires that MAC addresses are assigned to each IP you use. A routed setup requires that you add all of your IPs to the interface file. This can cause some issues. Customers can add additional IPs they have not paid for. If you use large subnets it would be easy for a client to guess what other IPs are in use.
With a Proxmox bridged network, you assign your IPs MAC addresses and should you require further IPs you simply assign the guest MAC address to any further additional IPs. Bridged networking also has the advantage of being able to use a Proxmox DHCP server to provide networking information. Because each IP is bound to a MAC address you can issue IPs via DHCP. Proxmox cloud templates default DHCP which is useful should a service like Cloud-init fail.
Configure Proxmox Bridged Networking
The interfaces file for Proxmox bridged networking is pretty simple. Our file below has our bridge on vmbr0 which is linked to our ethernet adapter on eno1. To find the name of your ethernet adapter use ip a. The bridge is configured with the business dedicated servers IPv4 and gateway. With bridged networking, there is no need to specify MAC addresses for each IPv6 address.
# network interfaces
auto lo
iface lo inet loopback
iface eno1 inet manual
auto vmbr0
iface vmbr0 inet static
address SERVER_IPV4/32
gateway GATEWAY_IP
bridge-ports eno1
bridge-stp off
bridge-fd 0
post-up echo 1 > /proc/sys/net/ipv6/conf/vmbr0/proxy_ndp
iface vmbr0 inet6 static
address 2001:41d0:xXx:xXXx::0001/128
gateway 2001:41d0:xXx:xXXx:ff:ff:ff:ff
post-up /sbin/ip -f inet6 route add 2001:41d0:203:7aff:ff:ff:ff:ff dev vmbr0
post-up /sbin/ip -f inet6 route add default via 2001:41d0:xXx:xXXx:ff:ff:ff:ff
pre-down /sbin/ip -f inet6 route del default via 2001:41d0:xXx:xXXx:ff:ff:ff:ff
pre-down /sbin/ip -f inet6 route del 2001:41d0:xXx:xXXx:ff:ff:ff:ff dev vmbr0
auto vmbr1
iface vmbr1 inet static
address 10.10.10.1
netmask 255.255.255.0
bridge-ports none
bridge-stp off
bridge-fd 0
bridge-vlan-aware yes
bridge-vids 2-4094
post-up echo 1 > /proc/sys/net/ipv4/ip_forward
post-up iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o vmbr0 -j MASQUERADE
post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o vmbr0 -j MASQUERADE
Proxmox Bridged Private Networking
For a Proxmox private network in a bridged environment, you simply specify the private network and assign it to a new interface. On most systems, this will be vmbr1. As with a routed setup, you can forward connections from the private network to vmbr0 which will allow outgoing internet access for each private IP. Because you are forwarding connections using IPtables there is no need to bridge the private network to your ethernet device and doing so would break your networking settings.
