sudo sshd -t

Example:
ubuntu1@ubuntu1-virtual-machine:/etc/ssh$ sudo sshd -t
/etc/ssh/sshd_config line 24: Deprecated option KeyRegenerationInterval
/etc/ssh/sshd_config line 25: Deprecated option ServerKeyBits
/etc/ssh/sshd_config: line 32: Bad configuration option: LogPath
/etc/ssh/sshd_config: line 33: Bad configuration option: LogMaxRotateFiles
/etc/ssh/sshd_config: line 34: Bad configuration option: LogMaxFileSize
/etc/ssh/sshd_config: line 35: Bad configuration option: LogRotationInterval
/etc/ssh/sshd_config line 42: Deprecated option RSAAuthentication
/etc/ssh/sshd_config: terminating, 4 bad configuration options