If an administrator is already set on the device and the password is unknown, a common factory default for access control systems like the ZK X7 is 1234 . How to Update or Reset Passwords
ZKTeco ZMM220 devices, the Telnet service is often restricted for internal development. However, multiple researchers and user guides have identified default credentials that may work depending on your firmware version. Stack Overflow Common Default Credentials for ZMM220 zmm220 default telnet password updated