Port 9999
Lantronix RS-485 Telnet Control
Port 9999 is commonly used by Lantronix device servers like the UDS-10 and UDS100 for remote Telnet configuration and management of serial-to-Ethernet converters, particularly those supporting RS-485 communication. This port allows network administrators to connect to the embedded Telnet service to configure network settings, serial parameters, or perform diagnostics on the device remotely..
Technical Details
Overview
Lantronix UDS series device servers provide a serial-to-Ethernet bridge that enables legacy RS-485 serial devices to be accessed over TCP/IP networks. These devices expose a Telnet management interface, typically running on TCP port 9999, facilitating configuration and control of the device's parameters remotely.
Protocol and Operation
The embedded Telnet server listens by default on TCP port 9999 and accepts plaintext commands from Telnet clients. Through this interface, users can:
- Assign network configuration parameters (IP address, gateway, etc.)
- Adjust serial communication settings (baud rate, parity, etc.)
- Manage operating modes such as transparent tunneling between serial and Ethernet
- Initiate diagnostics or firmware updates
The simplicity enables easy integration into network management workflows.
Ecosystem Integration
Port 9999 serves mainly during initial setup or troubleshooting of Lantronix UDS devices. In deployment, serial data is often tunneled through alternative dynamically configured ports, while the Telnet interface remains an auxiliary management channel, which can be optionally disabled after deployment for increased security.