How do I inspect a Linux bridge used by virtual machines or containers?
A Linux bridge connects network interfaces at layer 2 and is often used by hypervisors or container platforms. Guest connectivity depends on bridge membership, VLAN policy, uplink configuration and the provider’s MAC/IP rules. Deleting or reconfiguring the bridge can also disconnect the host’s own management address.
Before you start
- Authorised access to the dedicated server and the named inspection tools.
Instructions
1. Read bridge and port membership
Use the reporting commands to see which interfaces participate. A virtual NIC, bond or physical NIC can appear as a bridge port.
bridge link show
bridge vlan showInspect forwarding state and VLAN membership. Do not flush the forwarding database or remove ports as an initial diagnostic step.
2. Locate host addressing and uplinks
Compare the bridge with the interface holding the host’s IP and the physical path to the provider.
ip -br address
ip -d link show type bridgeSome providers require routed networking or registered virtual MACs instead of unrestricted bridging. Confirm the supported model before attaching guests.
Check the result
- The bridge design matches the hypervisor and provider requirements, with both host management and the intended guest network working.
Troubleshooting
- The host works but guests cannot reach the network
- Check guest addressing, bridge/VLAN membership and provider MAC filtering or routing requirements.
- Guests can reach each other only
- The local bridge may be healthy while the uplink or external routing is not.
- An unused bridge is suspected
- Verify dependencies before removal; a management IP or hidden guest can still rely on it.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.