How do dll files work?

Question

DLL

There is no awareness of the work of dll files. I realized that dlls are practically the same exes, i.e. PE files. But what is their difference? And, since these are the same executable files, is it possible to do at the beginning, for example, jmp my_function in the dll itself when it is imported? Or should the functions be called only from the program that imports the dll? How does the import work in general?

Answer 1

But what is their difference?

They don't have an entry point, so they can't just be picked up and run - that's one thing.
Two - a .NET assembly can be hidden under the .dll, and not a classic binary.

And, since these are the same executable files, is it possible to do at the beginning, for example, jmp my_function in the dll itself when it is imported?

It is impossible, because these are not executable files, but a set of functions.

How does the import work in general?

Dynamic linking

Answer 2

RUNDLL allows you to call individual functions .