Usually, the same network interface adapter (NIC) can be used for both port mirroring traffic and regular access of the server from a network.
But in some cases it is recommended (or even required) to install a separate NIC, which will be used solely for port mirroring purposes. These cases are following:
In these cases MiaRec should be connected to network switch with two NICs as shown on below diagram:

To prevent any conflicts with IP-addresses the first NIC should be switched to "stealth" mode with TCP/IP unbound from the card. You will need to open properties of NIC and disable IP stack and all other protocols (see below screenshot). This NIC will be used in listen mode only. No network packets will be sent from this NIC. That's why IP address is not necessary for it.
