Egypt's true military fortresses, as opposed to fortified towns, is very closely connected with the empire's frontiers. We can define Egypt's traditional frontiers as the Western Desert, the Sinai Desert to the east, the Mediterranean coast to the north and the First Nile cataract at Aswan in the south. These were the natural physical barriers that allowed protection to the Egyptians from outside interference during the early, predynastic period when this great civilization was formed. Later, while these boundaries helped maintain Egypt's independence during periods of relative weakness, they required fortification to do so. Of course, the fortresses became even more important over time, and as rulers such as Tuthmosis III expanded the Egyptian boarders to their farthermost extent into Syria and as far south as the Fifth Nile Cataract in Nubia.
Egypt, though-out its history, was more concerned with protecting its borders internally, within the country it self, rather than establishing forts or military garrisons in other countries.
There was a line of fortifications, along the so-called Horus Road, which carefully guarded Egypt from invasion from the East. The natural features of the Western Desert were considered to be protection from the Lybian area. There were forts built in the Sudan, the largest that at Buhen. Unfortunately, Lake Nasser has covered them all. Then to the North the country was antiquate in its protection by the sea.
So you can see, with a few exceptions through-out the years, Egypt concentraited on protecting its borders.