Why does Iran allow terrorists to p through from Iraq to Afghanistan?

What do you mean terrorists? Iran doesn't see the freedom fighters in Iraq as terrorists, after all the U.S and Britain invaded Iraq, of course Iran will be the enemy because they are the only ones to stand up to the U.S, Britain and Israel, Just remember the U.S armed the Mujahadeen in Afghanistan when they fought the Russians and now they have nothing to gain from it suddenly these people are terrorists.