In the new film “Untraceable,” FBI agents are desperate to track down a maniac who tortures people to death and broadcasts his crimes live over the Internet. To find the villain, the agents use the same Internet tools used by real-world cops and security experts – tools from DNSstuff LLC, a network security firm in Newburyport. “The producers contacted us, sent us the script, and asked if we could provide any input,” said DNSstuff’s chief executive, Rich Person. The company went further: It created Vector Trace, a cool-looking computer forensics tool that appears in the movie and will soon be available to DNSstuff’s customers…