tcp_keepalives settings not being set

Hello,

We have PostgreSQL 10.5 installed on RHEL 6 and I’m new to both. I’m in
the process of completing STIGs (Security Technical Implementation Guides)
for the Department of Defense. One of the STIGs mentions that we must
ensure our tcp_keepalives settings are configured in the postgresql.conf
file. I currently have these settings set to:

Tcp_keepalives_idle = 60

Tcp_keepalives_interval = 60

Tcp_keepalives_count = 2

I restarted the database and then ran SHOW_ALL; but it showed all 3
parameters set to 0.

After looking online, I saw a post where possibly Linux is not allowing
this to be configured and instead is using the OS parameters. When I ran
the command: sysctl -A | grep net.ipv4, it returned:

Net.ipv4.tcp_keepalive_time = 7200

Net.ipv4.tcp_keepalive_probs = 9

Net.ipv4.tcp_keepalive_intvl = 75

Is it possible Linux is not allowing these parameters to be configured via
the PostgreSQL config file?

Thanks in advance,

Dave Hughes