After you enter the correct username and password when you log on to the Linux ECS instance, you cannot log on to the instance. When this problem occurs, either the management terminal or the SSH client can log on normally, or both methods cannot log on normally. The following error message is displayed when you view the secure log.
pam_succeed_if(sshd:auth): requirement "uid >= 1000" not met by user "root".
Policy configuration of PAM-related modules. Users whose UID is less than 1000 are prohibited from logging in.
Take note of the following items:
- Before you perform high-risk operations such as modifying the specifications or data of an Alibaba Cloud instance, we recommend that you check the disaster recovery and fault tolerance capabilities of the instance to ensure data security.
- Before you modify the specifications or data of an Alibaba Cloud instance, such as an Elastic Compute Service (ECS) instance or an ApsaraDB RDS instance, we recommend that you create snapshots or enable backups for the instance. For example, you can enable log backups for an ApsaraDB RDS instance.
- If you have granted specific users the permissions on sensitive information, such as usernames and passwords, or submitted sensitive information in the Alibaba Cloud Management Console, we recommend that you modify the sensitive information at the earliest opportunity.
The configurations and descriptions in this topic have been tested in CentOS 6.5 64-bit operating systems. The configurations of other types and versions of operating systems may vary. For more information, see the official documentation of the corresponding operating system.