I need a working open source LAN limiter.

Hi! I started a new internet business within my locality. I connect my neighbours to the internet and they pay me at the end of the month. I realized that some of them carry out heavy downloads therefore adversely affecting the speed for the other clients. Is there an open source LAN limited that I can use to control how much bandwidth each of the clients get? I will appreciate if the limiter is also able to completely disconnect someone when necessary. Give a bit of review please!
