Usually scanning tools implement a switch in order to delay requests and not flood the target. Sometimes there tools that do not implement this delay option.

Is there a way to delay packets from tools that do not implement this option without touching the source code? I know that touching the source code is an option...the option I follow frequently. But I would like to know if there is any tool that exists to do that. Probably this tools, if exists, should be a kind of proxy that would store, in a buffer of some kind, all the packets the tool send and resend them introducing the configured delay.

Any ideas?