@stu Let me think. The first Linux server I exposed was in 2001. Fun Fact: my ISP used to truncate the connection if the traffic was low. My friend Simone ( @henomis - do you remember?) and I were supposed to take a university exam, and we had decided, as a practical demonstration, to do it by showing a real remote connection. Simone had written a rlogin daemon from scratch - as a project for the exam - and we wanted to demonstrate how we could connect from the university to my server at my parents' house (hundreds of kms away) and that it would work. So, I launched Napster just to keep the connection active, generating traffic. The professor was amazed and excited by our "alternative" approach.
I believe the first exposed FreeBSD server was around the end of 2002 or early 2003. But the first exposed server I did "professionally" (i.e., to host services for clients) was shortly after, probably at the end of 2003, and it was based on NetBSD.