what is the password when login using the ssh

[yongzhizhan]

i running the docker, and expose the port 2122.when i connect to the docker using ssh,the command is this : ssh root@10.10.8.166 -p 2122, it prompt me that :

$ ssh root@10.10.8.166 -p 2122
The authenticity of host '[10.10.8.166]:2122 ([10.10.8.166]:2122)' can't be established.
RSA key fingerprint is SHA256:a8Zv0AK3cp/h4JPs/hKDzyhZ5OxA6PURFxoQW2nILjw.
Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '[10.10.8.166]:2122' (RSA) to the list of known hosts.
root@10.10.8.166's password:

what's the password of root i enter?