DRAFT - DISA STIG for Oracle Linux 9
Rules and Groups employed by this XCCDF Profile
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Install the OpenSSH Server Package
Theopenssh-server
package should be installed. Theopenssh-server
package can be installed with the following command:$ sudo yum install openssh-server
Rule Medium Severity -
Enable the OpenSSH Service
The SSH server service, sshd, is commonly needed. Thesshd
service can be enabled with the following command:$ sudo systemctl enable sshd.service
Rule Medium Severity -
Verify Group Who Owns SSH Server config file
To properly set the group owner of/etc/ssh/sshd_config
, run the command:$ sudo chgrp root /etc/ssh/sshd_config
Rule Medium Severity -
Verify Owner on SSH Server config file
To properly set the owner of/etc/ssh/sshd_config
, run the command:$ sudo chown root /etc/ssh/sshd_config
Rule Medium Severity -
Verify Permissions on SSH Server config file
To properly set the permissions of/etc/ssh/sshd_config
, run the command:$ sudo chmod 0600 /etc/ssh/sshd_config
Rule Medium Severity -
Verify Permissions on SSH Server Private *_key Key Files
SSH server private keys - files that match the <code>/etc/ssh/*_key</code> glob, have to have restricted permissions. If those files are owned by the <code>root</code> user and the <code>root</code...Rule Medium Severity -
Verify Permissions on SSH Server Public *.pub Key Files
To properly set the permissions of/etc/ssh/*.pub
, run the command:$ sudo chmod 0644 /etc/ssh/*.pub
Rule Medium Severity -
Configure OpenSSH Client if Necessary
The following configuration changes apply to the SSH client. They can improve security parameters relwevant to the client user, e.g. increasing entropy while generating initialization vectors. Note...Group -
Verify the SSH Private Key Files Have a Passcode
When creating SSH key pairs, always use a passcode. <br> You can create such keys with the following command: <pre>$ sudo ssh-keygen -n [passphrase]</pre> Oracle Linux 9, for certificate-based auth...Rule Medium Severity -
Configure OpenSSH Server if Necessary
If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file <code>/etc/ssh/sshd_config</code>. The following recommendations can be app...Group -
Set SSH Client Alive Count Max
The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The option <code>ClientAliveInterval</code> configures time...Rule Medium Severity -
Set SSH Client Alive Interval
SSH allows administrators to set a network responsiveness timeout interval. After this interval has passed, the unresponsive client will be automatically logged out. <br> <br> To set this t...Rule Medium Severity -
Disable Host-Based Authentication
SSH's cryptographic host-based authentication is more secure than <code>.rhosts</code> authentication. However, it is not recommended that hosts unilaterally trust one another, even within an organ...Rule Medium Severity -
Enable SSH Server firewalld Firewall Exception
If the SSH server is in use, inbound connections to SSH's port should be allowed to permit remote access through SSH. In more restrictive firewalld settings, the SSH port should be added to the pro...Rule Medium Severity -
Disable SSH Access via Empty Passwords
Disallow SSH login with empty passwords. The default SSH configuration disables logins with empty passwords. The appropriate configuration is used if no value is set for <code>PermitEmptyPasswords<...Rule High Severity -
Disable GSSAPI Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. <br> The default SSH configuration disallows authentications based on GSSAPI. The appropriate c...Rule Medium Severity -
Disable Kerberos Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like Kerberos. <br> The default SSH configuration disallows authentication validation through Kerberos. The ...Rule Medium Severity -
Disable SSH Support for .rhosts Files
SSH can emulate the behavior of the obsolete rsh command in allowing users to enable insecure access to their accounts via <code>.rhosts</code> files. <br> The default SSH configuration disables su...Rule Medium Severity -
Disable SSH Root Login
The root user should never be allowed to login to a system directly over a network. To disable root login via SSH, add or correct the following line in <code>/etc/ssh/sshd_config</code>: <pre>Pe...Rule Medium Severity -
Disable SSH Support for User Known Hosts
SSH can allow system users to connect to systems if a cache of the remote systems public keys is available. This should be disabled. <br> <br> To ensure this behavior is disabled, add or c...Rule Medium Severity
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