okay i have a question..........i have of course a 97 blazer......so heres what i wanna know

on my windshield washer tank theres a little thing in the very front, if you remove the airbox.....you can see it, theres a little hose that connects to it, do you know what it is because it was throwing out a brown liquid that of course didnt not have a smell..........

is it for the rear window? ill take a pic tomarrow if i feel something wrong with my truck but i doubt it because im thinkink its old washer fluid