Localhost-only MCP server used cross-machine via reverse encrypted tunnel, zero exposed ports
XVX109 · reddit · 2026-08-21
The author demos an interesting transport pattern: an MCP server bound to 127.0.0.1 on a Mac is driven by a self-hosted agent (Hermes, controlled via self-hosted Mattermost from a phone) on a Linux box on another VLAN, creating tasks, setting statuses, tagging and commenting in the Mac desktop app.
The trick: the Mac opens an outbound encrypted link to the Linux box, and the server then appears on that box's loopback — the agent adds it as an ordinary Streamable HTTP MCP server with a bearer token. No inbound connections, no relay, no open ports.
Both read and write work, and the server's read-only mode correctly refuses writes from the remote agent. The author discloses being on the closed-source desktop app's dev team but posts for the transport pattern, which works with any local MCP server.
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