Transparent network devices intercept unidirectional network traffic and use bidirectional network protocol messages to discover each other and configure an inner connection. A first transparent network device intercepting unidirectional network traffic between a source and destination will send a bidirectional network protocol message addressed to the destination that includes an indicator of its presence. Additional transparent network devices that intercept this network message each add their own indicator to the message. If no response to the bidirectional network message is received, an error message is received, or a response message is received directly from the destination by one of the transparent network devices, this additional transparent network device deduces that it is the closest transparent network device to the destination and sends a response message addressed to the source that includes an indicator of its presence. The first transparent network device receives the response message and establishes an inner connection.