Bandwidth for specific user, MAC or IP address

Am running NethServer 6.6 not 7

By the way, this is what I use Nethserver for; As mailserver, and gateway…and once again like I told you am still fresh but very willing to learn as much as I can in UNIX/Linux. I would like to know the functionalities that NethServer can Play especially in Small Businesses like Micro-finance, Schools, Medical Centre, Supermarket etc.