Hello, first time poster so please go easy

I have a 2011 Mazda 6 Estate 2.2 diesel with 98k on the clock.

The other day when driving I heard what sounded to be a stone hit the under side of the car (under driver).

Thought nothing of it but today I noticed a small puddle of oil where my car had been parked. On closer inspection I believe I've found the source of the problem to be a small section of pipe protruding out of the bulk head (low passenger side).

​​There is nothing connected to it but clearly something should be, im just not sure what. I can't see any disconnected hoses down there so I'm wondering if it is a filling point for something and the cap has fell off (which could of been the noise I heard).

Can anyone enlighten me on what this pipe is and what should be connected to it? Apologies for the not so great pictures but it's the best I could manage.


Thanks in advance for any assistance

 

Looks like its the A/C drain. What colour was the fluid that came out?