--addr=<address> Set an external address on the bridge. The external address have to be on the same network as one of the host network interface. e.g. if eth0, wlan0, etc is on 192.168.0.2/24, you should put the address on the network 192.168.0.0/24. Please not that the CIDR notation have to be use.
--replace=<interface> In case you want to replace the main connexion of your computer so that only the vm will be able to reach the external network, replace interface by the interface you want to replace, and make sure that the --addr is set to one of the ip on the interace. Please not that it will be possible for your host to lost all connection to the external internet with this parametter.