Why the net.ipv4.tcp_timestamps parameter value not changes from 0 to 1 in /etc/sysctl.conf ?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Puppet

Issue

  • Facing the issue after around 30 minutes of changing the parameters net.ipv4.tcp_timestamps value from 0 to 1.
  • not able to modify the net.ipv4.tcp_timestamps from 0 to 1

Resolution

The parameter value gets changed from 1 to 0 due to the puppet-agent service running on the system. To fix the issue Stop/Disable the puppet-agent service on the affected system.

Root Cause

puppet-agent service Changed the parameter value from 1 to 0 on the system.

Diagnostic Steps

ipv4.tcp_timestamps value changed from 0 to 1:

# cat /etc/sysctl.conf | grep tcp_timestamps
net.ipv4.tcp_timestamps = 0
#

# vi /etc/sysctl.conf

# cat /etc/sysctl.conf | grep tcp_timestamps
net.ipv4.tcp_timestamps = 1             <<-----
# sysctl -p

After waiting for some time the puppet-agent changed the value as per the below log:

$ cat var/log/messages | grep -i timestamp
Sep 25 12:51:37 hostxxxxx puppet-agent[3601007]: (/Stage[main]/Linuxprofile::Common::V2229::Sysctl/Sysctl[net.ipv4.tcp_timestamps]/value) changed configuration value from '1' to '0' (corrective)    <<------

Sep 25 14:51:52 hostxxxxx puppet-agent[3668169]: (/Stage[main]/Linuxprofile::Common::V2229::Sysctl/Sysctl[net.ipv4.tcp_timestamps]/value) changed configuration value from '1' to '0' and live value from '1' to '0' (corrective)  <<------

puppet-agent active/Running on the issue node

$ cat systemctl_list-units | grep puppet
puppet.service                                             loaded active running   Puppet agent
$

The parameter net.ipv4.tcp_timestamps value changed from 1 to 0:

# sysctl -a | grep timestamp
net.ipv4.tcp_timestamps = 0           <<-----     
$

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