What This Port Carries
Port 775 is officially registered for moira_db, the database service for Moira—MIT's Project Athena Service Management System.1 The port operates over TCP and was used for client connections to the centralized Moira database server.
This isn't a port most people encounter today. It's a historical artifact from academic computing in the 1980s and early 1990s, when MIT was building one of the first large-scale distributed computing environments that actually worked.
The Moira Story
In the mid-1980s, MIT's Project Athena faced an impossible problem: how do you manage thousands of users, hundreds of machines, dozens of network services, and countless mailing lists across a distributed computing environment? Nothing like this existed yet. There was no Active Directory, no LDAP, no centralized directory services as we know them today.
So they built Moira.
Moira was a massive centralized database that stored everything Athena needed to function: user accounts, machine configurations, network service settings, mailing list memberships, cluster information, and authentication data.2 Every Athena service—from email to file servers to cluster workstations—queried Moira to know who users were, what they could access, and how the network should be configured.
The system consisted of several components:3
- A database (initially RTI INGRES, later migrated to Oracle)
- A server process that answered queries on port 775
- A data distribution manager that pushed configuration changes to services
- Client tools for administrators and users to query and modify data
Authentication used Kerberos 4, another Project Athena innovation that became the foundation for modern network authentication.4
The name "Moira" comes from the Greek concept of fate. Until 1989, the system was called SMS (Service Management System), but since everything else at Athena had a Greek name—and since too many other things were also called SMS—they renamed it after the Moirai, the three Fates who controlled the thread of life in Greek mythology. An appropriate name for a system that controlled the entire Athena environment.
Why This Port Matters
Port 775 represents a moment in computing history when universities were solving problems that didn't have solutions yet. Project Athena proved that distributed computing could work at scale, that centralized directory services made sense, and that you could build systems that thousands of people depended on daily.
The ideas in Moira influenced what came later: LDAP directories, Active Directory, modern identity management systems. The Kerberos authentication system Moira used became an Internet standard still in use today.
Most ports in the well-known range carry protocols everyone uses. Port 775 carries something different: a reminder that someone had to figure this out first, before distributed computing was normal, before centralized user management was obvious.
Current Status
Moira is still maintained by MIT as part of their Athena infrastructure,5 though modern deployments likely use different port configurations and protocols than the original 1980s implementation.
You won't find moira_db running on port 775 outside MIT and a few academic institutions that adopted Project Athena's tools. The port number still appears in /etc/services files on Unix systems,6 a fossil from when MIT's innovations were being standardized into the operating systems everyone used.
Some port databases list alternative service names for port 775—acmaint_transd and acmaint-transd7—but these appear to be unofficial or system-specific uses with minimal documentation.
Checking What's Listening
On Unix-like systems, check if anything is listening on port 775:
Unless you're connected to MIT's Athena environment or running legacy Project Athena software, you'll find nothing. And that's fine. Not every port needs to carry traffic. Some ports exist as historical markers, reminders of the problems people solved before the solutions became invisible infrastructure.
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