Make sure your kernel config has the bridge interface, /etc/loader.conf
if_bridge_load="YES"
Create a bridge:
$ sudo ifconfig bridge0 create
check your new sysctls
$ sudo sysctl net.link.bridge net.link.bridge.ipfw: 0 net.link.bridge.pfil_member: 1 net.link.bridge.pfil_bridge: 1 net.link.bridge.ipfw_arp: 0 net.link.bridge.pfil_onlyip: 1
Check that the interfaces are up, but otherwise unconfigured, then
$ sudo ifconfig bridge0 addm ep0 addm ep1 up0
make permanent with /etc/rc.conf entries:
ifconfig_ep0="up" ifconfig_ep1="up" cloned_interfaces="bridge0" ifconfig_bridge0="addm ep0 addm ep1 up"