Is it permissible to buy ropes that originated from the port, and are being taken out by workers at the port and sold to me, knowing that officials and customs are aware of this, and that some say they are waste products that are burned, while others say they are stolen, and is the profit obtained from selling them unlawful?

If people disagree about the source of goods from a Muslim vendor, the default ruling is that purchasing is permissible unless it is overwhelmingly probable that the goods are stolen. If it is overwhelmingly probable that they are stolen, then purchasing them is forbidden.

Whoever buys something that he predominantly believes to be stolen, his ruling is that of a usurper.