Trivial Service Discovery Protocol

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Trivial Service Discovery Protocol
Developer secondtruthLabs
Status Stable
First published 2025
Latest version 1.0
Transport UDP Multicast
Default port(s) 7920
Encoding UTF-8
License Public Domain


The Trivial Service Discovery Protocol (TSDP) is a minimal UDP multicast protocol for zero-configuration service discovery on local and trusted networks. Developed by secondtruthLabs, it enables automatic discovery of services without requiring a central registry.

Overview[edit | edit source]

TSDP provides a simple mechanism for services to announce their presence and for clients to discover available services. It is protocol-agnostic and can be used to discover any type of service.

Design philosophy[edit | edit source]

  • Trivial enough to implement in an afternoon
  • Protocol-agnostic discovery
  • Multicast-based for zero-config operation
  • Secure enough for trusted networks

Technical specification[edit | edit source]

Network configuration[edit | edit source]

Parameter Value
Multicast Address 239.255.83.68
Port 7920
Transport UDP
Max Message Size 512 bytes

Message format[edit | edit source]

Messages are single-line, space-separated plain text:


Message format
{{{code}}}


Commands[edit | edit source]

Command Direction Description
DISCOVER Client → Network Request services matching criteria
ANNOUNCE Service → Network Announce service availability
GOODBYE Service → Network Announce service shutdown

Examples[edit | edit source]

Discovery request
{{{code}}}


Service announcement
{{{code}}}


Shutdown notice
{{{code}}}


Wildcards[edit | edit source]

The * character serves as a wildcard:

  • DISCOVER * * * – Discover all services
  • DISCOVER agentfinger * * – Discover all AgentFinger services
  • DISCOVER * myservice * – Find specific service ID across protocols

Metadata[edit | edit source]

Optional key-value pairs appended to messages:


Metadata format
{{{code}}}


Spaces in values must be URL-encoded.

Protocol support[edit | edit source]

TSDP can discover services for any protocol:

Security considerations[edit | edit source]

TSDP is designed for trusted local networks. It does not provide:

  • Authentication
  • Encryption
  • Access control

Deployments on untrusted networks should use additional security measures such as VPNs or network segmentation.

See also[edit | edit source]

References[edit | edit source]


External links[edit | edit source]