Which command allows you to control how the bridging behaves?

The command that allows you to control how bridging behaves is brctl. This command is part of the Bridge utilities package and is specifically designed to manage Ethernet bridge devices in Linux. It enables you to create and manage bridge interfaces, which are used to connect two or more network segments at the data link layer.

Using brctl, an administrator can perform actions such as adding interfaces to a bridge, deleting them, or showing the status of the bridges in the system. It provides a straightforward way to define how packets are forwarded across different interfaces within the bridge.

In contrast, other commands such as bridge also manage bridges but are part of the newer utilities intended to eventually replace brctl. ifenslave is utilized for managing Ethernet bonding rather than bridging, and ip link is part of the iproute2 package, which primarily deals with network interface configuration but does not specifically focus on bridging behavior. Therefore, brctl is the correct choice for controlling Ethernet bridging in a more established context.