Port 416: Silverplatter — The CD-ROM Search Engine

Port 416 is assigned to Silverplatter, a protocol for an information retrieval system that predated web search engines. Both TCP and UDP use this port.¹

What SilverPlatter Was

SilverPlatter Information, Inc. was founded in 1983 in the United Kingdom by Béla Hatvany and Walt Winshall.² The company was one of the first to produce commercial reference databases on CD-ROMs—bringing MEDLINE, PsycINFO, ERIC, and other academic databases to university libraries.

Their software was called SPIRS (SilverPlatter Information Retrieval Software). Students and researchers would sit at library terminals, insert a CD-ROM, and search through hundreds of thousands of journal citations. Port 416 enabled networked access to SilverPlatter servers, allowing multiple users to query databases without passing around physical discs.

This was revolutionary. Before SilverPlatter, finding research meant browsing printed indices. After SilverPlatter but before the web, this was how you found papers.

The Protocol

The SilverPlatter protocol allowed client software to:

• Connect to database servers over TCP or UDP port 416
• Send search queries using Boolean operators and field-specific searches
• Retrieve bibliographic records and abstracts
• Download citations for offline use

The system supported both local CD-ROM searching and networked server queries. Port 416 was the network component—the door through which libraries connected to centralized SilverPlatter servers.

What Happened to It

SilverPlatter thrived through the 1990s as the standard for electronic research databases. But the web changed everything. Web-based interfaces like OVID and EBSCOhost replaced CD-ROM systems. Google Scholar made academic search free and instant.

In 2001, SilverPlatter was sold to Wolters Kluwer for $113 million and absorbed into Ovid Technologies.² The SilverPlatter brand disappeared. The protocol stopped being used. Port 416 went silent.

Current Status

Port 416 is still officially assigned to "silverplatter" in the IANA registry,¹ but no modern systems use it. The service is extinct. If you find port 416 open on a system today, it's either:

• A very old library system that was never updated
• Something else entirely using the port unofficially
• A misconfiguration

To check what's listening on port 416:

# Linux/Mac
sudo lsof -i :416
sudo netstat -tlnp | grep :416

# Windows
netstat -ano | findstr :416

Why This Port Matters

Port 416 represents a specific moment in the history of information access. There was a time—roughly 1985 to 2000—when digital search meant SilverPlatter. Medical students searched MEDLINE on SilverPlatter. Psychology researchers used PsycINFO on SilverPlatter. Educators queried ERIC through SilverPlatter.

Every query flowed through systems like this one, through ports like 416, before the Internet made it all seem obvious and instant.

The port is a memorial to infrastructure that mattered deeply and then vanished completely. Google didn't invent database searching. It just made everyone forget what came before.

Related Ports

Other database and information retrieval services occupied nearby well-known ports in the same era, though few remain in active use today.