Where are Gog and Magog located?

>Eze 38:2 Son of man, set thy face against Gog, the land of Magog, the chief prince of Meshech and Tubal, and prophesy against him Which are the countries/locations mentioned here in this verse? When I heard some sermon long back, the preacher was comparing it with some countries. What is the authenticity of that? What present day countries are where Gog and Mogag are/were/will be, and how can we verify this?