The Photon operating system must send TCP timestamps.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-258894	PHTN-40-000232	SV-258894r933743_rule		Medium

Description
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.

STIG	Date
VMware vSphere 8.0 vCenter Appliance Photon OS 4.0 Security Technical Implementation Guide	2023-10-29

Details

Check Text ( C-62634r933741_chk )
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 (F-62543r933742_fix)
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.