The Photon operating system must send TCP timestamps.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-239184	PHTN-67-000113	SV-239184r816674_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 6.7 Photon OS Security Technical Implementation Guide	2022-09-27

Details

Check Text ( C-42395r675358_chk )
At the command line, execute the following command: # /sbin/sysctl -a --pattern "net.ipv4.tcp_timestamps$" Expected result: net.ipv4.tcp_timestamps = 1 If the output does not match the expected result, this is a finding.

Fix Text (F-42354r816673_fix)
Open /etc/sysctl.conf with a text editor. Add or update the following line: net.ipv4.tcp_timestamps = 1 Run the following command to load the new setting: # /sbin/sysctl --load