The SSH daemon must be configured to use only FIPS 140-2 approved ciphers.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38617	RHEL-06-000243	SV-50418r1_rule		Medium

Description
Approved algorithms should impart some level of confidence in their implementation. These are also required for compliance.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2015-05-26

Details

Check Text ( C-46176r1_chk )
Only FIPS-approved ciphers should be used. To verify that only FIPS-approved ciphers are in use, run the following command: # grep Ciphers /etc/ssh/sshd_config The output should contain only those ciphers which are FIPS-approved, namely, the AES and 3DES ciphers. If that is not the case, this is a finding.

Fix Text (F-43566r1_fix)
Limit the ciphers to those algorithms which are FIPS-approved. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. The following line in "/etc/ssh/sshd_config" demonstrates use of FIPS-approved ciphers: Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc The man page "sshd_config(5)" contains a list of supported ciphers.