What Port 810 Carries
Port 810 is officially assigned to FCP Datagram—the datagram variant of FirstClass Protocol, a proprietary communications protocol used by FirstClass groupware servers to send notifications to clients.1
While the main FirstClass client-server communication happened over TCP port 510, port 810 handled the FC Notifier service—essentially push notifications for email, conference updates, and file changes.2
The FirstClass Protocol
FirstClass Protocol (FCP) was a transport layer protocol that guaranteed error-free communications for all activities.3 Unlike protocols that relied on underlying error correction, FCP implemented its own sliding window protocol with packet sizes tuned to different network types.
Every FCP packet included a "task number" identifier—similar to port numbers in TCP/IP—allowing multiple virtual links between each client and server. This meant you could upload files, download messages, and read mail simultaneously without blocking.4
The protocol ran over modems, AppleTalk, Novell IPX, and eventually TCP/IP. When running over reliable transports like TCP, later versions could disable their own error correction to avoid redundant overhead.5
The FirstClass System
FirstClass debuted in 1990 as EduNet, an educational networking system combining email, conferencing, and file sharing.6 By the mid-1990s, it had evolved into groupware software competing directly with Microsoft Exchange and Lotus Notes.
For a brief moment, it was winning. FirstClass beat Exchange in installed users until 1997.7 Schools loved it. Small businesses deployed it. The software provided features that felt futuristic—threaded discussions, file sharing, real-time notifications—years before these became standard.
But FirstClass added Internet functionality and scripting late. By 2000, both Lotus and Microsoft had implemented these features first, and FirstClass lost market share.8
What Happened to FirstClass
The protocol didn't die—it just became irrelevant. As organizations migrated to Exchange, Gmail, and modern collaboration platforms, FirstClass installations dwindled. The notification service on port 810 stopped flowing. The servers were decommissioned.
Port 810 remains assigned in the IANA registry, a marker of where an entire category of software used to live. The protocol that pioneered integrated groupware—email, conferencing, file sharing, all in one system—is now a historical footnote.
Security Considerations
Port 810 traffic on modern networks is extremely rare. If you see unexpected traffic on this port, investigate immediately:
- Legitimate: If you're running a FirstClass server (unlikely in 2026), port 810 carries notification traffic
- Suspicious: Unknown services bound to port 810 could indicate misconfigured software or malicious activity
- Confusion: Some network scanning tools may misidentify port 810 traffic
The protocol implemented optional Blowfish encryption,9 but by modern standards, any remaining FirstClass deployments should be considered insecure and migrated.
Check What's Listening
To see if anything is using port 810 on your system:
Linux/macOS:
Windows:
If you find unexpected listeners, investigate what process owns the port and whether it should be there.
The Port's Place in History
Port 810 represents a specific moment in computing history—the early 1990s, when proprietary protocols competed with open standards, when groupware was a new concept, when educational institutions were figuring out how to network their schools.
FirstClass Protocol was good engineering. It solved real problems—multitasking communications, cross-platform compatibility, error correction over unreliable links. The protocol's task-based virtual links predated modern microservices by decades.
But good engineering doesn't always win. Open standards won. Web-based systems won. The Internet won. And FirstClass Protocol became a historical curiosity, preserved only in IANA port assignments and the memories of sysadmins who once ran those servers.
Frequently Asked Questions
War diese Seite hilfreich?