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Linux bridge utilities (brctl)

brctl is a command-line utility used for managing Ethernet bridges on Linux systems^[600-developer-docker-docker-bridge.md]. It allows administrators to configure the network bridge interface itself and manage which physical or virtual interfaces are attached to it^[600-developer-docker-docker-bridge.md].

Common Commands

The utility provides several subcommands to handle bridge lifecycle and configuration^[600-developer-docker-docker-bridge.md].

  • Add a bridge: Creates a new logical bridge instance. 
    brctl addbr br0
  • Add an interface: Attaches a network device (e.g., eth0) to the bridge, making it a part of the bridge. 
    brctl addif br0 eth0
  • Delete an interface: Removes a network device from the bridge. 
    brctl delif br0 eth0
  • Delete a bridge: Removes the logical bridge instance. 
    brctl delbr br0
  • Show configuration: Lists all existing bridges and the interfaces currently attached to them. 
    brctl show

Installation

The brctl tool is provided by the bridge-utils package^[600-developer-docker-docker-bridge.md]. On RPM-based distributions like CentOS, it can be installed via yum^[600-developer-docker-docker-bridge.md].

yum install bridge-utils

Configuration

While brctl handles the runtime attachment of devices, persistent network configuration (such as assigning static IPs to the bridge) is typically handled by distribution-specific configuration files^[600-developer-docker-docker-bridge.md].

For example, on RHEL/CentOS systems, a bridge file might be configured at /etc/sysconfig/network-scripts/ifcfg-br0 with TYPE=Bridge, while the physical Ethernet configuration file (e.g., ifcfg-eth0) must include the directive BRIDGE=br0 to link the device to the bridge^[600-developer-docker-docker-bridge.md].

  • [[Docker networking]]
  • [[Linux networking]]

Sources

^[600-developer-docker-docker-bridge.md]