Wondering how to Create Private Network Bridge on Proxmox? We can help you.
Proxmox is a great platform to create virtual machines and containers.
We can use it to easily migrate instances to other connected nodes.
As part of our Server Management Services, we assist our customers with several Promox queries.
Today, let us discuss Private Network Bridge on Proxmox VE 6 with NAT
Create Private Network Bridge on Proxmox
In Proxmox virtualization infrastructure, we can do the network configuration in two ways:
- Via the CLI (manually editing network configuration files)
- From an intuitive graphical user interface.
We can choose either method. However, the choice depends on our Linux administration expertise.
Create Virtual Network Bridge on Proxmox With NAT
For the CLI method, we edit /etc/network/interfaces configuration files directly:
$ sudo vim /etc/network/interfaces
We create a virtual network bridge based on the below network parameters:
- Network: 192.168.48.0
- Network mask: 255.255.255.0
- Proxmox host IP: 192.168.48.1
Then we print current active network interfaces on the server:
$ sudo ip -f inet a s 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 inet 192.168.58.236/26 brd 188.8.131.52 scope global enp4s0 valid_lft forever preferred_lft forever
On the other hand, we create a virtual bridge named vmbr1:
auto vmbr1 iface vmbr1 inet static address 192.168.48.1 netmask 255.255.255.0 bridge_ports none bridge_stp off bridge_fd 0
Here, we can see that there is no physical interface that links to the bridge.
Configure NAT (Masquerading)
Masquerading allows VMs in a private network to access the external networks. It is possible by using the host IP address for outgoing traffic.
iptables rewrite each outgoing packet to appear as originating from the host. In addition, it rewrites the responses accordingly to route to the original sender.
Moving ahead, we will modify the above network configurations to add routing for internet connectivity.
Since primary interface enp4s0 connects to the physical switch and has internet connectivity, we route traffic coming from vmbr1 through it.
auto vmbr1 iface vmbr1 inet static address 192.168.48.1 netmask 255.255.255.0 bridge_ports none bridge_stp off bridge_fd 0 post-up echo 1 > /proc/sys/net/ipv4/ip_forward post-up iptables -t nat -A POSTROUTING -s ‘192.168.48.0/24’ -o enp4s0 -j MASQUERADE post-down iptables -t nat -D POSTROUTING -s ‘192.168.48.0/24’ -o enp4s0 -j MASQUERADE
Here, enp4s0 can replace with a VLAN interface or another Linux bridge.
Bring up the bridge interface
We can validate those network configurations by manually bringing up the bridge interface.
$ sudo ifup vmbr1 Waiting for vmbr1 to get ready (MAXWAIT is 2 seconds).
Then we check the bridge IP information:
$ ip address show dev vmbr1 3: vmbr1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 16:cf:7e:23:de:1e brd ff:ff:ff:ff:ff:ff inet 192.168.48.1/24 brd 192.168.50.255 scope global vmbr1 valid_lft forever preferred_lft forever inet6 fe80::14cf:7eff:fe23:de1e/64 scope link valid_lft forever preferred_lft forever
From the output, we can see that the IP address on the vmbr1 is correct.
Then we should be able to restart the networking service without any failures:
$ sudo systemctl restart networking
Eventually, we confirm the status is active:
$ systemctl status networking.service ● networking.service – Raise network interfaces Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled) Active: active (exited) since Fri 2021-05-07 19:27:34 CEST; 29s ago Docs: man:interfaces(5) Process: 27355 ExecStart=/sbin/ifup -a –read-environment (code=exited, status=0/SUCCESS) Main PID: 27355 (code=exited, status=0/SUCCESS) May 07 19:27:29 proxmox systemd: Starting Raise network interfaces… May 07 19:27:34 proxmox ifup: Waiting for DAD… Done May 07 19:27:34 proxmox ifup: Waiting for vmbr1 to get ready (MAXWAIT is 2 seconds). May 07 19:27:34 proxmox systemd: Started Raise network interfaces.
Once we create a Virtual machine on the bridge, it will behave as if it directly connects to the physical network.
The network, in turn, sees each virtual machine as having its own MAC, even though there is only one network cable connecting all of these VMs to the network.
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In short, we saw an effective method our Support Techs employ to create a Private Network Bridge on Proxmox.