In sshd_config(5), to avoid confusion with PermitRootLogin options. Original:
If this option is set to *prohibit-password* or *without-password*, password and keyboard-interactive authentication are disabled for root. Proposed: If this option is set to *prohibit-password* (renamed from *without-password* to avoid ambiguity, both valid) only non keyboard-interactive authentication (public-key, hostbased and GSSAPI) is allowed for root. --- sshd_config.5.orig Mon Oct 9 22:12:51 2017 +++ sshd_config.5 Fri Oct 13 12:38:13 2017 @@ -1199,9 +1199,10 @@ .Pp If this option is set to .Cm prohibit-password -or -.Cm without-password , -password and keyboard-interactive authentication are disabled for root. +(renamed from +.Cm without-password +to avoid ambiguity, both valid) only non keyboard-interactive authentication +(public-key, hostbased and GSSAPI) is allowed for root. .Pp If this option is set to .Cm forced-commands-only , *** A related question. About these messages (/var/log/authlog): ... error: maximum authentication attempts exceeded for root ... ... error: maximum authentication attempts exceeded for invalid user admin ... Is there any reason why the connection isn't just terminated after confirming the user is root or invalid?