Per executable UDP port redirection possible?

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http://unix.stackexchange.com – I have a black box program which listens on a particular UDP port. I'd like it to listen to a UDP port of my choosing. Is there a way to trick the executable into listening on a differen port. I might imagine there exists a library which could be injected with LD_PRELOAD that might incercept the system calls and facilitate this. A virtual machine of course is the heavy handed option, but that's not an option for me. (HowTos)