Certain aspects of the invention relate to a connector including at least one first connector part and at least one second connector part. The connector parts can be connected to one another in a fluid-tight manner and can be locked to one another via at least one closure element. One of the connector parts has at least one sealing element (e.g., a septum or a sealing disk) that blocks a throughflow in the closed state and which can be opened, and the other one of the connector parts has at least one opening element for opening the sealing element. One of the connector parts has at least one projection and the other one of the connector parts has at least one receiver, and the opening element and the sealing element are arranged with respect to one another such that the opening element only opens the sealing element when the projection has been introduced into the receiver.