MCP Server

DDNS provides a standard-library-only MCP server so clients such as GitHub Copilot can inspect local cached status or run one complete DDNS synchronization after user approval. Provider credentials are never returned in protocol arguments or results.

Configuration path precedence is -c/--config > DDNS_CONFIG > the conventional local config paths. MCP mode accepts exactly one local file; remote URLs and multiple -c values are rejected.

stdio (default)

ddns mcp -c /etc/ddns/config.json

stdio mode opens no network listener. stdout is reserved for one JSON-RPC message per line, while runtime logs go to stderr.

Add the server directly to GitHub Copilot CLI:

copilot mcp add ddns -- ddns mcp -c /etc/ddns/config.json

Alternatively, add the following to an MCP client configuration:

{
  "mcpServers": {
    "ddns": {
      "command": "ddns",
      "args": ["mcp", "-c", "/etc/ddns/config.json"]
    }
  }
}

Escape Windows path backslashes as \\ in JSON, or replace command with the absolute path to the ddns executable.

Streamable HTTP

Start a standalone HTTP MCP server:

ddns mcp -c /etc/ddns/config.json --transport http

The default endpoint is http://127.0.0.1:9876/mcp. The Web console also exposes /mcp on its listener.

Standalone mode and Web share these options:

Option	Description
--host	Bind host; defaults to 127.0.0.1 and accepts a LAN address or 0.0.0.0 / ::
--port	Listener port, default 9876; use 0 to let the OS select one
--http-token	Shared Web API and HTTP MCP token; visible ASCII without spaces
--http-origin ORIGIN	Exact HTTP(S) origin allowed to access /mcp; repeatable

Listener precedence is command line > root JSON http > DDNS_HTTP_* environment variables > 127.0.0.1:9876.

When loopback has no token, the Web APIs (including full configuration and provider credentials) and /mcp are unauthenticated. A non-loopback or wildcard listener requires a non-empty token. MCP clients send it as Authorization: Bearer <token>.

DDNS does not provide TLS. Put LAN listeners behind a trusted HTTPS reverse proxy that preserves Authorization, Host, and Origin. Browser access through a TLS-terminating proxy must list the exact public HTTPS origin in http.origins or --http-origin, even when the public page appears same-origin; native MCP clients may omit Origin.

HTTP supports MCP 2026-07-28 only. Each message is a separate POST to /mcp using Content-Type: application/json with MCP-Protocol-Version and Mcp-Method; tool calls also require Mcp-Name. Accept must list both application/json and text/event-stream.

This tools-only implementation returns plain JSON and does not provide SSE, sessions, legacy HTTP, resources, prompts, or subscriptions.

Available tools

Tool	Arguments	Behavior
get_ddns_status	None	Read local configuration, cached addresses and records, provider summaries, and the latest sync time; it does not query providers live
update_dns_records	None	Resolve current addresses using the configuration, synchronize every configured record once, and return the resulting status

update_dns_records changes external DNS state, so clients should retain user confirmation before invoking it. The tool accepts no domain, address, provider, or credential arguments, preventing a model from bypassing the local configuration to write arbitrary records.

Protocol and runtime limits

• stdio supports MCP 2026-07-28 and the 2025-11-25 initialize lifecycle.
• HTTP supports MCP 2026-07-28 only.
• When a stdio client cancels an update, the server stops before subsequent IP rules, domain records, or providers.
• HTTP provides no SSE cancellation; work may continue after a client disconnects.
• A provider API request already sent cannot be rolled back.
• Status comes from the local cache. With caching disabled, a later request in another process cannot reconstruct previous sync history, although the update call still returns its own result.
• Do not let multiple Web, MCP, or system-task processes update the same configuration concurrently.