SLA monitoring and reporting to customers

["Rubens Kuhl Jr." <rubensk () gmail com>]

What open-source or low-budget tools are operators using for SLA
monitoring when the reports (current state and historical) should be
available to customers ?

Looking at NANOG archives, NAGIOS is the most prevalent tool, but its
authorization mechanisms are somewhat below I would like so customers
could not change anything both in configuration and in SLA software
state.

I'm looking for something more like Cacti, where customers can be
contained to only see some of the generated graphs.

Thanks for any input,
Rubens