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The Photon operating system must send TCP timestamps.


Overview

Finding ID Version Rule ID IA Controls Severity
V-239184 PHTN-67-000113 SV-239184r675360_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 2021-04-15

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-42354r675359_fix)
At the command line, execute the following commands:

# sed -i -e "/^net.ipv4.tcp_timestamps/d" /etc/sysctl.conf
# echo net.ipv4.tcp_timestamps=1>>/etc/sysctl.conf