sshd サービスを開始できない

Issue

• sshd.service が、以下のエラーを表示して失敗します。

[root@rhel78 ~]# systemctl status sshd.service -l
● sshd.service - OpenSSH server daemon
   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
   Active: activating (auto-restart) (Result: exit-code) since Wed 2021-12-22 18:42:40 IST; 18s ago
     Docs: man:sshd(8)
           man:sshd_config(5)
  Process: 23085 ExecStart=/usr/sbin/sshd -D $OPTIONS (code=exited, status=255)
 Main PID: 23085 (code=exited, status=255)

Dec 22 18:42:40 rhel78 systemd[1]: Failed to start OpenSSH server daemon.
Dec 22 18:42:40 rhel78 systemd[1]: Unit sshd.service entered failed state.
Dec 22 18:42:40 rhel78 systemd[1]: sshd.service failed.