127.0.0.1 and relays each connection through the control plane to the container’s port on the platform network.
Flags
What is allowed
- Only a port the service declares: its routed port, a published container port, or a port the image EXPOSEs. Anything else is refused with the allowed list.
- Only that app’s own container. Another app’s service is never reachable, and a service name cannot be used to reach a sibling.
- Only apps on the control plane node, like the database tunnel.
- The same permission as exec and the terminal: operator (root ability) on the app. Viewers are refused.
Limits and audit
Each open and close is written to the audit log (app.tunnel.open, app.tunnel.close) with the service, port and bytes in each direction.
The dashboard shows the exact command, with a Copy button, on the app Overview tab.