How to start rexecd daemon in RedHat 7.9 ?

Dear Sir:
Our client is using RedHat 7.9
and I need to make "rexec command" work

For this, I found that "rexecd daemon" must be started.
I guess this daemon uses port number 512

In RedHat 7.9, xinetd service manages rsh, rlogin, rexec together
It (xinetd) started rsh by default, I guess and rsh uses port 514
However port 512 is not enabled now

So I guess, the main problem is, rexecd daemon is not running now
I tried to make it run by following google search help.
However, I cannot figure out how to enable rexecd daemon

So could anyone of you please help me with this main issue?

I need to run a command like below

rexec -l kxenadmin -p kxenadmin localhost (some command)

Thank you, everyone and have a nice day