# Preparing a delegate host

Use this procedure to prepare a RHEL/CentOS host as a Control Center delegate host.
1. Log in to the candidate delegate host as root, or as a user with superuser privileges.
2. Disable the firewall, if necessary.
This step is required for installation but not for deployment. For more information, refer to the Control Center Planning Guide.
1. Determine whether the firewalld service is enabled.
systemctl status firewalld.service
• If the result includes Active: inactive (dead), the service is disabled. Proceed to the next step.
• If the result includes Active: active (running), the service is enabled. Perform the following substep.
2. Disable the firewalld service.
systemctl stop firewalld && systemctl disable firewalld
On success, the preceding commands display messages similar to the following example:
rm '/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service'
rm '/etc/systemd/system/basic.target.wants/firewalld.service'
3. Optional: Enable persistent storage for log files, if desired.
By default, RHEL/CentOS systems store log data only in memory or in a ring buffer in the /run/log/journal directory. By performing this step, log data persists and can be saved indefinitely, if you implement log file rotation practices. For more information, refer to your operating system documentation.
mkdir -p /var/log/journal && systemctl restart systemd-journald
4. Enable and start the Dnsmasq package.
The package facilitates networking among Docker containers.
systemctl enable dnsmasq && systemctl start dnsmasq
If name resolution in your environment relies solely on entries in /etc/hosts, configure dsnmasq so that containers can use the file:
1. Open /etc/dnsmasq.conf with a text editor.
2. Locate the line that starts with #domain-needed, and then make a copy of the line, immediately below the original.
3. Remove the number sign character (#) from the beginning of the line.
4. Locate the line that starts with #bogus-priv, and then make a copy of the line, immediately below the original.
5. Remove the number sign character (#) from the beginning of the line.
6. Locate the line that starts with #local=/localnet/, and then make a copy of the line, immediately below the original.
7. Remove net, and then remove the number sign character (#) from the beginning of the line.
8. Locate the line that starts with #domain=example.com, and then make a copy of the line, immediately below the original.
9. Replace example.com with local, and then remove the number sign character (#) from the beginning of the line.
10. Save the file, and then close the editor.
11. Restart the dnsmasq service.
systemctl restart dnsmasq
5. Install and configure the NTP package.
1. Install the package.
yum install ntp
2. Set the system time.
ntpd -gq
3. Enable the ntpd daemon.
systemctl enable ntpd
4. Configure ntpd to start when the system starts.
Currently, an unresolved issue associated with NTP prevents ntpd from restarting correctly after a reboot. The following commands provide a workaround to ensure that it does.
echo "systemctl start ntpd" >> /etc/rc.d/rc.local
chmod +x /etc/rc.d/rc.local