RHEL 9 SSH daemon must not allow known hosts authentication.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-258006 | RHEL-09-255150 | SV-258006r1045071_rule | CCI-000366 | medium |
| 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. | ||||
| STIG | Date | |||
| Red Hat Enterprise Linux 9 Security Technical Implementation Guide | 2025-05-14 | |||
Details
Check Text (C-258006r1045071_chk)
Verify the SSH daemon does not allow known hosts authentication 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*ignoreuserknownhosts'
IgnoreUserKnownHosts yes
If the value is returned as "no", the returned line is commented out, or no output is returned, this is a finding.
Fix Text (F-61671r1045070_fix)
Configure the SSH daemon to not allow known hosts authentication.
Add the following line to "/etc/ssh/sshd_config" or to a file in "/etc/ssh/sshd_config.d", or uncomment the line and set the value to "yes":
IgnoreUserKnownHosts yes
The SSH service must be restarted for changes to take effect:
$ sudo systemctl restart sshd.service