Ran was the counter-intelligence service of the Jewish settlement in Mandate Palestine. It was established by Shaul Avigur (Meirov) and Yehuda Arazi (Tannenbaum), the latter a member of the Palestine Police Force. Arazi joined the police on orders from the Haganah, and rose to become a police inspector in the Criminal Investigation Department (CID).
Ran's primary aim was to thwart the intelligence gathering operations of the British, Germans, Italians and Americans.
References
Ran (Haganah unit) Wikipedia(Text) CC BY-SA