Port 267 is officially assigned to td-service (Tobit David Service Layer), a unified messaging platform from Germany that predates Microsoft Teams, Slack, and most modern collaboration tools.1 It's been running since 1996. You've probably never heard of it.
What Is Tobit David?
Tobit David is a German-engineered unified communications platform that handles email, fax, SMS, voice calls, and messaging—all in one system.2 The software runs on-premise on Windows servers, deliberately avoiding the cloud. It's GDPR-compliant by design, which matters deeply in Europe.
The company behind it, Tobit.Software, was founded in 1986 in Ahaus, Germany.3 They started with fax software (Faxware) in the early 1990s, when fax was how business happened. In 1996, they expanded into email and SMS, creating the first version of David. The system still exists today, serving companies that want messaging infrastructure they control completely.
How Port 267 Works
Port 267 operates on both TCP and UDP protocols.1 It's the Service Layer (SL) endpoint—where client applications connect to the David server. When you open the David client on your desktop, it establishes a connection to port 267 on the server to access your messages, faxes, and communications.
The Tobit David system uses multiple ports for different services:
- Port 267: Service Layer for client connections4
- Port 268: REPLIKA (Replica Server Host)
- Port 1049: Tobit David Postman VPMN
This is infrastructure designed for reliability, not for viral growth. It solves a specific problem: giving organizations complete control over their communications without depending on Microsoft, Google, or any cloud provider.
Why This Port Matters
Port 267 represents a category of Internet infrastructure that exists beneath the surface of mainstream awareness. While everyone knows about port 443 (HTTPS) or port 25 (email), thousands of ports serve specific protocols, specific software, specific communities.
Tobit David has been running for nearly 30 years. Companies in Germany, Austria, and Switzerland have built their entire communication workflows around this system.3 They've sent millions of faxes, emails, and messages through port 267. The protocol works. The software updates. The port remains open.
This is what the well-known port range (0-1023) was designed for: officially registered services with stable, predictable endpoints. Port 267 fulfills that purpose perfectly, even if most network administrators will never encounter it.
The Well-Known Port Range
Port 267 sits in the well-known port range (0-1023), which is managed by IANA (Internet Assigned Numbers Authority).5 Ports in this range are assigned through formal IETF Review or IESG Approval procedures. They're meant for services that need a stable, universally recognized endpoint.
Most ports in this range are famous: SSH (22), HTTP (80), HTTPS (443). Others, like port 267, serve specific communities with unwavering reliability. Both types matter. The Internet runs on infrastructure that most people never see.
Security Considerations
Port 267 is a legitimate service port, but like any listening port, it's a potential entry point. If you're running Tobit David:
- Ensure only authorized clients can reach port 267
- Use firewall rules to restrict access to trusted networks
- Keep the David server software updated with security patches
- Monitor connection logs for unusual activity
If you're not running Tobit David and see port 267 open during a security scan, investigate immediately. Either someone installed David without documentation, or something else is masquerading on this port.
How to Check What's Listening
To see if anything is listening on port 267 on your system:
On Linux/Mac:
On Windows:
If Tobit David is installed and running, you'll see the David service process bound to this port. If you see something else—or nothing when David should be running—that's worth investigating.
Related Ports
- Port 268: Tobit David REPLIKA (Replica Server Host)4
- Port 1049: Tobit David Postman VPMN
- Port 25: SMTP (Simple Mail Transfer Protocol) - email transport
Frequently Asked Questions
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