The "--tee" option of iptables can mirror network packets to a target ip address. With this feature, you can deploy monitoring easily when you have an embed Linux gateway or bridge.
In this example, we're using an ubuntu gateway. Syntax to setup iptables port mirroring:
sudo iptables -t mangle -A POSTROUTING -j TEE --gateway 192.168.1.200
WFilter in "192.168.1.200" will be able to monitor all network clients.