The SSH client must be configured to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms.

From VMware ESXi Server 5.0 Security Technical Implementation Guide

Associated with: CCI-001128

SV-51261r3_rule The SSH client must be configured to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms.

Vulnerability discussion

DoD information systems are required to use FIPS 140-2 approved cryptographic hash functions.

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Disable lock down mode. Enable the ESXi Shell. Execute the following command(s): # grep -i macs /etc/ssh/ssh_config Re-enable lock down mode. If the returned list contains MACs other than a variant of the hmac-sha1 or hmac-sha2 form, this is a finding. If the /etc/ssh/ssh_config file does not exist or the MACs option is not set, this is not a finding.

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Disable lock down mode. Enable the ESXi Shell. Execute the following command(s): # vi /etc/ssh/ssh_config Add/modify the attribute line entry to the following (quotes for emphasis only): "MACs " The above list "may" include any number of the following (current) comma-separated variants: hmac-sha1, hmac-sha1-96, hmac-sha2-256, hmac-sha2-256-96, hmac-sha2-512, hmac-sha2-512-96. Re-enable lock down mode.

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