How to access private fields without friend functions?

Question

C++ / C#

Let's say we need to write a List class. We have a Node class. Correctly, all fields of a class should be private. But how then can you get access to the private fields of the Node in the List without friend-functions?

Answer 1

friend class :)

Answer 2

via pointer)

Answer 3

It's not clear what the relationship between List and Node is.
In a correct way, private fields should be private, and those that need access from the outside should be public or protected.