Port 64: Covia — The Airline Middleware That Taught Machines to Translate

Port 64 is assigned to Covia, specifically to the Communications Integrator (CI), a piece of middleware that once cost $750,000 per license¹. It was registered for both TCP and UDP by Dan Smith, whose email address placed him at Galileo's Denver operations center: dan.smith@den.galileo.com².

If you have never heard of Covia, you have almost certainly used what it became.

What the Communications Integrator Did

The Communications Integrator sat between applications and networks. That sounds simple. It was not.

In the late 1980s and early 1990s, enterprise computing was a landscape of incompatible machines running incompatible operating systems connected by incompatible network protocols. If you had an application on an IBM mainframe and needed it to talk to a Tandem system, you rewrote code. If you needed that same application to work over a different network protocol, you rewrote code again.

The Communications Integrator eliminated this. It positioned itself beneath the application but above the network protocol, creating a translation layer that masked routing information, the operating system, and the network protocol from the application¹. An application written once could run across disparate hardware and network architectures without recompilation.

IBM, Tandem, Digital Equipment Corporation, NCR, and Unisys all signed licensing agreements¹. The Open Software Foundation wanted to include it in their Distributed Computing Environment. Sun Microsystems considered bundling it as an add-on to Open Network Computing¹.

This was not a niche product. This was the Rosetta Stone for enterprise networks.

The Story: From Apollo to Galileo

Covia Technologies did not start as a middleware company. It started as an airline reservation system.

In 1971, United Airlines launched Apollo, one of the first computerized airline booking systems³. By 1976, Apollo terminals were installed in travel agent offices across the country. The system worked so well that by 1986, United spun it off into its own company and called it Covia, headquartered in Rosemont, Illinois, with 2,700 employees across offices in Atlanta, Denver, and Austin⁴.

Covia was 50% owned by UAL Inc., United Airlines' parent company. The other half was owned by a consortium of airlines including British Airways¹. The problem Covia solved daily was the same problem the Communications Integrator would solve for the broader computing world: making incompatible systems cooperate.

Airlines ran on different hardware. Travel agents connected through different networks. Booking a flight from Chicago to London meant routing a transaction across systems that were never designed to talk to each other. Covia built the middleware to make this seamless, then realized the solution applied far beyond air travel.

In 1992, Covia merged with Europe's Galileo reservation system to form Galileo International, creating the world's first global computer reservation system⁵. The merger brought together North American airlines (United, USAir, Air Canada) with European carriers (British Airways, KLM, Alitalia, Swissair, and others)⁵.

By 1993, Covia was porting the Communications Integrator to SunSoft's Solaris⁶. By 2000, Galileo International held 26.4% of worldwide airline reservation system bookings³.

The Apollo system itself survived until March 3, 2012, when United Airlines finally switched to SHARES after its merger with Continental Airlines³. Galileo was absorbed into Travelport, where it continues to operate alongside Worldspan. The Communications Integrator's DNA lives on in travel industry infrastructure.

The Technical Insight

What made the Communications Integrator valuable enough to command $750,000 per license was a single architectural decision: isolate the application from everything below it.

The software defined a programming interface that applications could target. Below that interface, the Communications Integrator handled:

• Network protocol translation across incompatible networking environments
• Hardware abstraction across IBM, Tandem, DEC, NCR, and Unisys systems
• Routing transparency so applications never needed to know how data got where it was going
• Message-based distributed computing enabling transaction processing across heterogeneous networks

This is middleware in its purest form. Today we take protocol abstraction for granted. In 1990, it was radical enough that the Open Software Foundation, IBM, and Sun Microsystems were all competing to integrate it into their platforms¹.

Port 64 Today

Port 64 sits in the well-known port range (0-1023), ports reserved by IANA for system-level services. These assignments require IETF Review or IESG Approval⁷.

You are unlikely to encounter port 64 in active use on modern networks. The Communications Integrator's era of incompatible enterprise systems has largely been replaced by TCP/IP standardization, RESTful APIs, and message brokers like Kafka and RabbitMQ. The problem CI solved still exists, but the solutions have moved up the stack.

To check if anything is listening on port 64:

# macOS / Linux
sudo lsof -i :64
netstat -an | grep ':64 '

# Windows
netstat -an | findstr :64

If something is listening on port 64 on your machine and you did not put it there, investigate. This port has no common modern use, and unexpected listeners on well-known ports warrant attention.

Security

Port 64 has been historically flagged in some threat databases as a port used by certain trojans for communication². This does not mean port 64 is inherently dangerous. Malware can use any port. But because port 64 has no common modern service, traffic on it is anomalous by default, which makes it both a potential indicator of compromise and easy to monitor.

If your firewall logs show unexpected connections on port 64, take them seriously. Legitimate traffic on this port in 2025 would be unusual.

The Bigger Picture

Port 64 tells a story about the lifecycle of infrastructure. A company born from airline reservations built middleware so powerful that IBM, DEC, and Sun all wanted it. That middleware claimed a well-known port. Then the world standardized around TCP/IP and HTTP, the airlines merged and re-merged, and the middleware's problem domain shrank until the port became a quiet monument to a solved problem.

But the problem was real. In 1990, making an IBM mainframe talk to a Tandem system across different networks was genuinely hard. Someone at Covia, working out of a Denver office that served Galileo International's operations, registered port 64 so that the Communications Integrator could listen for connections from machines that had no other way to understand each other.

That is what ports are. Not just numbers. Doors that someone opened because something on the other side needed to connect.