AlmaLinux OS 9 SSH daemon must not allow known hosts authentication.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-269267	SRG-OS-000480-GPOS-00227	ALMA-09-021140	SV-269267r1050149_rule	2025-02-20	1

Description
Configuring the IgnoreUserKnownHosts setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere.

ℹ️ Check
Verify the SSH daemon does not allow known hosts authentication with the following command: $ sshd -T \| grep ignoreuserknownhosts ignoreuserknownhosts yes If the value is returned as "no", this is a finding.

✔️ Fix
Configure the SSH daemon to not allow known hosts authentication. Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes": IgnoreUserKnownHosts yes Alternatively, add the setting to an include file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: $ echo 'IgnoreUserKnownHosts yes' > /etc/ssh/sshd_config.d/40-knownhosts.conf Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service

✔️ Fix

Configure the SSH daemon to not allow known hosts authentication. Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes": IgnoreUserKnownHosts yes Alternatively, add the setting to an include file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: $ echo 'IgnoreUserKnownHosts yes' > /etc/ssh/sshd_config.d/40-knownhosts.conf Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service