BaselineWatch
Desk
Your fleet and your work Fleetyour releases and the hardware they run onTriagewhat needs a decisionWatchlistthe products and platforms you runSaved searchesthe lists you come back to
This instance Sourceswhat is read, how often, under what termsDigestthe daily or weekly summary, and alerts
How it is drawn Appearancethe look and the colour schemeBrandingthe mark this instance wears
Owner sign-in

RHEL-10-700540 RHEL 10 must be configured so that the Secure Shell (SSH) daemon does not allow known hosts authentication.

DISA STIG library V1R3
All changes in this version
first version loaded CAT II

Maps to SI-6 via CCI-002696

Title

RHEL 10 must be configured so that the Secure Shell (SSH) daemon does not allow known hosts authentication.

Control

Verify RHEL 10 SSH daemons do 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' /etc/ssh/sshd_config.d/10-stig.conf:IgnoreUserKnownHosts yes Verify the runtime setting with the following command: $ sudo sshd -T | grep -i ignoreuserknownhosts ignoreuserknownhosts yes If the "IgnoreUserKnownHosts" keyword is not set to "yes" in a drop-in that lexicographically precedes 50-redhat.conf, or if no output is returned, this is a finding.

Discussion

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. OpenSSH uses the first occurrence of a keyword it sees, and drop-in files are read in lexicographical order at the start of the configuration. Red Hat recommends using drop-in files rather than changing base configuration files.

Related controls

CCI-002696

Fix

Configure RHEL 10 SSH daemons to not allow known hosts authentication. In "/etc/ssh/sshd_config.d", create a drop file that will lexicographically precede 50-redhat.conf and add the following line: IgnoreUserKnownHosts yes Restart the SSH service with the following command for the changes to take effect: $ sudo systemctl restart sshd.service