Limit cps per source IP and port

Hi, is it possible to limit the number of calls per source ip and port before the dialplan? I know that this can be done using mod_limit in the dialplan, i was thinking of a limit like the sessions-per-second global limit, this way less resources are used if some ip/port is flooding our machine. Another possibility is using the firewall... but i like this option less because i wont know of the drop calls. Thanks, -- Saludos / Regards / Cumprimentos António Silva