Description
By default, the SSH configuration allows any user with an account
to access the system. There are several options available to limit
which users and group can access the system via SSH. It is
recommended that at least one of the following options be leveraged:
- AllowUsers variable gives the system administrator the option of
allowing specific users to ssh into the system. The list consists of
space separated user names. Numeric user IDs are not recognized with
this variable. If a system administrator wants to restrict user
access further by specifically allowing a user’s access only from a
particular host, the entry can be specified in the form of user@host.
- AllowGroups variable gives the system administrator the option of
allowing specific groups of users to ssh into the system. The list
consists of space separated group names. Numeric group IDs are not
recognized with this variable.
- DenyUsers variable gives the system administrator the option of
denying specific users to ssh into the system. The list consists of
space separated user names. Numeric user IDs are not recognized with
this variable. If a system administrator wants to restrict user
access further by specifically denying a user’s access from a
particular host, the entry can be specified in the form of user@host.
- DenyGroups variable gives the system administrator the option of
denying specific groups of users to ssh into the system. The list
consists of space separated group names. Numeric group IDs are not
recognized with this variable.
Rationale
Specifying which accounts are allowed SSH access into the system reduces the
possibility of unauthorized access to the system.
Warning
Automated remediation is not available for this configuration check
because each system has unique user names and group names.
