Legacy Telnet devices

Workflow

Telnet sends account, password, commands and output in plaintext and cannot verify server identity. It is disabled by default; use it only when the connection explicitly allows an unencrypted protocol, target and task match, and the human accepts the visible risk.

Boundary and checks

Prefer migration to SSH, HTTPS or another encrypted management protocol. Each fixed script line follows a prompt; success means the dialogue completed, not that a business change took effect.

Only for unavoidable legacy devices

Telnet sends account, password, commands and results in cleartext and cannot verify server identity. SecretBridge disables it by default. Enable “allow insecure protocol” per resource only for a device that cannot be upgraded on a trusted, isolated management network. Prefer SSH, HTTPS or a vendor’s secure management protocol.

Fixed login dialogue and approval

Resource type, address, account and credential reference must match the task. A template fixes account, password and command prompts, an optional authentication-failure prompt, a 1–32 line command script, exit command and output limit. The user checks the target, complete script and cleartext risk in the local approval page; an AI cannot supply arbitrary new commands at run time.

The broker sends the account, password from the OS credential store and each script line after the expected prompts. It filters bound password echoes before storing or returning output. Success means the scripted dialogue completed, not that a business change took effect: Telnet has no universal remote exit code. Cancellation, disconnection, timeout or output overflow closes the connection, but the device state still needs checking.

Once the temporary need ends, disable the resource’s insecure-protocol permission and remove its templates. Do not disable TLS or host-key verification on other protocols to make a test pass.