Chapter 2. Prerequisites

Procedure 2.1. Disabling the Network Manager Service

1. Verify whether Network Manager is currently enabled:

   # systemctl status NetworkManager.service | grep Active:

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   • The system displays an error if the Network Manager service is not currently installed. If this error is displayed, no further action is required to disable the Network Manager service.
   • The system displays Active: active (running) if Network Manager is running, or Active: inactive (dead) if it is not. If Network Manager is inactive, no further action is required.
2. If Network Manager is running, stop it and then disable it:

   # systemctl stop NetworkManager.service
   # systemctl disable NetworkManager.service

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3. Open each interface configuration file on the system in a text editor. Interface configuration files are found in the /etc/sysconfig/network-scripts/ directory and have names in the format ifcfg-X, where X is replaced by the name of the interface. Valid interface names include eth0, p1p5, and em1.
   To ensure that the standard network service takes control of the interfaces and automatically activates them on boot, confirm that the following keys are set in each interface configuration file, or add them manually:

   NM_CONTROLLED=no
   ONBOOT=yes

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4. Start the standard network service:

   # systemctl start network.service

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5. Configure the network service to start at boot time:

   # systemctl enable network.service

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Procedure 2.2. Disabling the firewalld Service

1. Install the iptables service:

   # yum install iptables-services

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2. Review the iptables rules defined in /etc/sysconfig/iptables:

   Note

   You can review your current firewalld configuration:

   # firewall-cmd --list-all

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3. When you are satisfied with the iptables rules, disable firewalld:

   # systemctl disable firewalld.service

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4. Stop the firewalld service and start the iptables services:

   # systemctl stop firewalld.service; systemctl start iptables.service; systemctl start ip6tables.service

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5. Configure the iptables services to start at boot time:

   # systemctl enable iptables.service
   # systemctl enable ip6tables.service

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