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The SSH daemon must not allow authentication using known hosts authentication.


Overview

Finding ID Version Rule ID IA Controls Severity
V-75841 UBTU-16-030300 SV-90521r2_rule Medium
Description
Configuring this setting for the SSH daemon provides additional assurance that remote logon via SSH will require a password, even in the event of misconfiguration elsewhere.
STIG Date
Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide 2018-07-18

Details

Check Text ( C-75529r1_chk )
Verify the SSH daemon does not allow authentication using known hosts authentication.

To determine how the SSH daemon's "IgnoreUserKnownHosts" option is set, run the following command:

# grep IgnoreUserKnownHosts /etc/ssh/sshd_config

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-82471r2_fix)
Configure the SSH daemon to not allow authentication using known hosts authentication.

Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes":

IgnoreUserKnownHosts yes

The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command:

# sudo systemctl restart sshd.service