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The Photon operating system must send Transmission Control Protocol (TCP) timestamps.


Overview

Finding ID Version Rule ID IA Controls Severity
V-256576 PHTN-30-000107 SV-256576r887402_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 7.0 vCenter Appliance Photon OS Security Technical Implementation Guide 2023-02-21

Details

Check Text ( C-60251r887400_chk )
At the command line, run 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-60194r887401_fix)
At the command line, run the following commands:

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