STIGQter: STIG Summary: Red Hat Enterprise Linux 9 Security Technical Implementation Guide Version: 2 Release: 9 Benchmark Date: 01 Jul 2026:

The RHEL 9 SSH server must be configured to use only Message Authentication Codes (MACs) employing FIPS 140-3 validated cryptographic hash algorithms to protect the confidentiality of SSH server connections.

DISA Rule

SV-257991r1184311_rule

Vulnerability Number

V-257991

Group Title

SRG-OS-000250-GPOS-00093

Rule Version

RHEL-09-255075

Severity

CAT I

CCI(s)

CCI-001453 - Implement cryptographic mechanisms to protect the integrity of remote access sessions.

Weight

Fix Recommendation

Configure the RHEL 9 SSH server to use only MACs employing FIPS 140-3 approved algorithms.

Reinstall crypto-policies with the following command:

$ sudo dnf -y reinstall crypto-policies

Set the crypto-policy to FIPS with the following command:

$ sudo update-crypto-policies --set FIPS

Setting system policy to FIPS

Note: Systemwide crypto policies are applied on application startup. It is recommended to restart the system for the change of policies to fully take place.

Check Contents

Verify the SSH server is configured to use only MACs employing FIPS 140-3 approved algorithms.

To verify the MACs in the systemwide SSH configuration file, use the following command:

$ sudo grep -i MACs /etc/crypto-policies/back-ends/opensshserver.config

MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha2-512

If the MACs entries in the "opensshserver.config" file have any hashes other than "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha2-512", or they are missing or commented out, this is a finding.

Vulnerability Number

V-257991

Documentable

False

Rule Version

RHEL-09-255075

Severity Override Guidance

Check Content Reference

Target Key

5551