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 | CCI-000366 | 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-258894r933743_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.