If a ship ends its move in a sector that contains a wormnet portal and has at least one operational engine, then it may traverse the portal as part of its movement.  You may specify an exit portal, but unless you have acquired navigation data about both the entry and exit portals, your exit portal will be determined randomly.  You can specify an exit portal for which you expect to receive navigation data from another empire on the same turn, but if the donor empire fails to provide you with this information, your exit portal will be selected randomly.
 
Once you have traversed a wormnet, you will receive navigation data for both the entry and exit portals of your journey.  You may then navigate safely between those portals without error.  You will not know if there are other portals connected to that same wormnet unless you continue to explore random exits, or until another empire gives you the navigation data for those other portals.
 
If a wormnet portal drifts to a different sector during the Astronomics phase any planned entry from its previous sector will fail, and any exits from that portal will end up in the new sector.  If a wormnet portal collapses altogether, all movement into or out of it is cancelled.
 
Allies: Only allied empires can traverse temporary portals created by warpdrone devices.