You can check what the player is colliding with without bouncing them away with it, which would suit the ladder information, and you can shoot a ray down to determine the distance to the floor. In my mmorpg I use ode and only detect the floor through rays to determine where you can walk. (Real physics are a lot harder to network).
I use the distance of the collision at the next point the player is walking to see if the height difference is too great, and if not I set the player to be at that height.
