Hubs are best serviced with cone wrenches, usually sold in sets. I like to have to sets of 14, 15 17 and 17 mm wrenches. I don't use them for anything else as their narrowness means they are easily marred. I've found regular greasing and adjustment will extend the life of the cones and cups a long time, and if the cones get pitted it can be difficult to find replacement cones to fit. Same is true for headsets.