Set up the KVM network bridge on a Virtualizor server

KVM VPSs on a Virtualizor server connect to the network through a Linux bridge on the host. If the Virtualizor KVM network bridge is wrong, new VPSs have no network, so it is worth checking right after installation and before selling servers.

Before you start

• Root SSH and IPMI or console access to the server: bridge changes can cut your connection.
• The main interface name (ip -br link) and your IP, gateway and netmask.
• Virtualizor installed with KVM (install a KVM master or slave node).

Check the default bridge

Virtualizor's KVM installer normally creates a bridge (commonly named viifbr0) that holds the server's main IP. Check it:

ip -br addr

bridge link

You should see the bridge with your main IP and the physical NIC attached to it. In the admin panel, open Servers → Edit Server (or the server's settings) and confirm the bridge name matches.

Use a custom bridge

1. Create the bridge in the OS network configuration from the console, moving the main IP from the NIC to the bridge.
2. Restart networking and confirm the server is reachable.
3. Set the bridge name in the server's settings in the Virtualizor admin panel.
4. Create a test VPS and check it gets network.

IP blocks and MAC addresses

• Extra IP blocks must be routed to the server or allowed on its switch port.
• Some data centres drop traffic from unknown MAC addresses; ask for virtual MACs or a routed block (bridges, NAT and VLANs).
• Add the block to an IP pool for that server (IP pools).

Internal (private) networks

For private traffic between VPSs, create a second bridge without a public IP (or on a second NIC) and add an internal IP pool that uses it, if your Virtualizor version supports internal networking.

Troubleshooting

• Server unreachable after install: log in via console and check the bridge configuration and default route.
• New VPSs have no network: wrong bridge name in server settings, wrong gateway in the IP pool, or the block is not routed (no network troubleshooting).
• Only some VPSs work: MAC filtering by the provider.

Frequently asked questions

Can I use bonding with the bridge?

Yes, attach a bond interface to the bridge instead of a single NIC.

Do OpenVZ or Xen use the same bridge?

Networking differs by virtualisation type; this guide covers KVM.

Should the bridge have the main IP?

Yes, in the normal bridged setup the host's IP lives on the bridge.

Next steps

• IPv6 pools
• Slave server offline
• Add a slave server