← Back to VMware vSphere 8.0 vCenter Appliance Photon OS 4.0 Security Technical Implementation Guide

V-258894

CAT II (Medium)

The Photon operating system must send TCP timestamps.

Rule ID

SV-258894r933743_rule

STIG

VMware vSphere 8.0 vCenter Appliance Photon OS 4.0 Security Technical Implementation Guide

Version

V1R1

CCIs

CCI-000366

Discussion

TCP timestamps are used to provide protection against wrapped sequence numbers. It is possible to calculate system uptime (and boot time) by analyzing TCP timestamps. These calculated uptimes can help a bad actor in determining likely patch levels for vulnerabilities.

Check Content

At the command line, run the following command to verify TCP timestamps are enabled:

# /sbin/sysctl net.ipv4.tcp_timestamps

Expected result:

net.ipv4.tcp_timestamps = 1

If the "net.ipv4.tcp_timestamps" kernel parameter is not set to "1", this is a finding.

Fix Text

Navigate to and open:

/etc/sysctl.d/zz-stig-hardening.conf

Add or update the following line:

net.ipv4.tcp_timestamps = 1

At the command line, run the following command to load the new configuration:

# /sbin/sysctl --load /etc/sysctl.d/zz-stig-hardening.conf

Note: If the file zz-stig-hardening.conf does not exist, it must be created.