sshd: Did not receive identification string

[mike <mike--v@wp.pl>]

Hello

What does this log entry mean?

Mar 23 09:44:17 xxx sshd[7920]: Did not receive identification string from 218.53.214.11
Mar 23 09:47:31 xxx sshd[7925]: Did not receive identification string from 218.53.214.11

That some *** tried to login twice and did not make it, or was it just
a portscan, a connect without any "transaction"?

Question #2: How to move sshd to some higher port?

Thanks
mike