Recently one of our linux server in the cloud was not coming up after reboot. When we checked with vendor, he said it may be due to sshd_config file not configured properly. There was also file system corruption issue during that time. We are not sure if it was really a file system corruption issue or sshd_config file misconfiguration issue which made server unbootable.
The sshd_config file was configured as below: AllowUsers user1 user2 user3 user4 user5 AllowUsers user6 user7 AllowUsers user8 AllowUsers user9
As per the vendor there can't be multiple entries for AllowUsers so the entries for user6 user7 user8 user9 are invalid. AllowUsers user6 user7 AllowUsers user8 AllowUsers user9
I went though some blogs including Red-hat https://access.redhat.com/discussions/3872831 but it’s not clear from anywhere whether this is a correct configuration or not. Also, is there any way if sshd_config configuration can be validated?