Water pump leak 1998 ML320

[supradupe]

Hi all, Help me identify the source of the leak, please.

There is some brownish liquid dripping down the lower radiator hose where it connects to the water pump. The stuff is water soluble and smells sort of fishy or rusty. Since there is not much room to peep and I know its not leaking from the hose connection. Is it possible that the water pump cracked? I am still puzzled with the brown color, seems like rusty water/coolant. the coolant inside the expansion tank is clear so I don't think the rust is from inside. Any thoughts? The ML in question is a 98 with 66k miles on it, water pump is original.

Attached pictures: first one as seen when look up from the bottom of truck to water pump pulley.