Ensure the device is behind a robust firewall that blocks port 23 from external traffic. If you'd like, I can help you further if you tell me: The specific model number of your ZKTeco device.
Note: The specific credential pair depends on the OEM manufacturer utilizing the ZMM220 board, but the "root" access is almost always available via Telnet. zmm220 default telnet password
If remote access is necessary, check if your firmware supports SSH, which provides encrypted communication unlike the clear-text nature of Telnet. How to Login (Step-by-Step) Ensure the device is behind a robust firewall
If the device is connected to a cloud server, the telnet port might be restricted by the server's firewall rules. Common Uses for Telnet Access If remote access is necessary, check if your
Security research and community findings suggest several credential sets that the manufacturer has historically used for Telnet access across ZMM220-based platforms: / Password:
The ZMM220 is a core hardware platform and kernel used in many