RHEL 9 SSHD must accept public key authentication.

Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased. Multifactor authentication requires using two or more factors to achieve authentication. A privileged account is defined as an information system account with authorizations of a privileged user. A DoW common access card (CAC) with DoW-approved PKI is an example of multifactor authentication.

Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000106-GPOS-00053, SRG-OS-000107-GPOS-00054, SRG-OS-000108-GPOS-00055

Note: If the system administrator demonstrates the use of an approved alternate multifactor authentication method, this requirement is Not Applicable.

Verify that RHEL 9 SSH daemon accepts public key encryption with the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*pubkeyauthentication'

PubkeyAuthentication yes

If "PubkeyAuthentication" is set to no, the line is commented out, or the line is missing, this is a finding.

To configure the system, add or modify the following line in "/etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d".

PubkeyAuthentication yes

Restart the SSH daemon for the settings to take effect:

$ sudo systemctl restart sshd.service