We had to layover at IKA for 10 hours (daytime) in May 2017.
Nobody attends the transfer desk.
No transit hall. You should just wait at the space before the border control area.
No facilities at all. (Correction: The toilet is located quite far but you can use it anyway.) Some metallic chairs along the wall. You are in the middle of rushing crowd when a new flight arrives.
Nobody cares. The security collects your passport and orders to just wait.
The best place to test your patience.
We were given our boarding pass 20 minutes before the boarding time (even though we were flying on business class and kept on asking about lounge service.) and could go to the air-side.
We found at the boarding gate that our bags were not arrived to IKA with us. Terrific.
This bureaucratic transit system certainly ruins the good image of Iran (if there is any.)