It'd help if you described what you were wanting to do.
"Stop a redirect in an iframe" doesn't convey anything. Your site has another site in an iframe that you don't want redirected, or your site is in the iframe of someone else's site? Redirected with meta tag? Redirected with javascript? What is the purpose of the redirect? What is the purpose of stopping the redirect?
Without completely spelling out what you're wanting, no one knows what it is you're looking for.