PROBLEM: rc.local script is not supported on version 7 of xenserver, I cannot add iptables rule at startup

SOLUTION: Go to the Xenserver CLI - command line interface. Execute this two commands:

# chmod u+x /etc/rc.d/rc.local
# systemctl start rc-local

Note: The initial file permissions are not set to allow for scripts to be executed, so you'd see beforehand:

# ls -l /etc/rc.d/rc.local
-rw-r--r--. 1 root root 473 Jun 14 06:36 /etc/rc.d/rc.local

"systemctl" command should make it run across reboots. If you run the check first, you should see it disabled initially:

# systemctl status rc-local
   rc-local.service - /etc/rc.d/rc.local Compatibility
   Loaded: loaded (/usr/lib/systemd/system/rc-local.service; static; vendor preset: disabled)
   Active: inactive (dead)