Hello.

I am trying to get a bandwidth monitoring solution up and i'd like to know what are my options.
Basically i am a small ISP (300-500 hosts) and would like to also provide vps services and monitor IN/OUT bytes per month for all ip addressess in a /24 range or w/e(doesnt matter much)

Now i could set up cacti but it wouldl tell me the overall bandwidth as per my router's eth.

What solution can i use that can monitor the in/out bandwidth per each ip addr i am routing (each customer) ?

I would look into tc linux traffic shaping. I'm not sure if the solution I propose will be applicable to your settings but here it is:

1) Use iptables to mark packets and track data usage.

2) use tc and iptables (details about implementation can be found at lartc.org)
-use tc to set different classes with rate limits and ceils that suit your need.
-use iptables to mark packets from a specific mac address
-use tc to direct packets with certain marks set by iptables to your traffic shaping rules.
-have tc output data usage

I was also able to find this thanks to google: http://www.docum.org/docum.org/monitor/

I'm sure there are various ways to accomplish what you need and may take some time to get the right solution to your problem.

thank you, i appreciate what you are saying, however i want monitoring not shaping.
even so, this could work i guess but it would require some tech know-how for anyone wanting to view the stats.
i am looking for an already made open source solution that has a web-frontend with little tech background required by users.

for anyone else interested/having the same "problem" so far i've found bandwidthd, ntop, darkstat but i'm having some difficulties trying to monitor a specific network (i just see all the traffic everywhere, and -ntop wise-, it's a resource overkill)

sounds just like zabbix.