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Chapter 8. Preparing a remote installation by using VNC
8.1. Overview
The graphical user interface is the recommended method of installing RHEL when you boot the system from a CD, DVD, or USB flash drive, or from a network using PXE. However, many enterprise systems, for example, IBM Power Systems and 64-bit IBM Z, are located in remote data center environments that are run autonomously and are not connected to a display, keyboard, and mouse. These systems are often referred to as headless systems and they are typically controlled over a network connection. The RHEL installation program includes a Virtual Network Computing (VNC) installation that runs the graphical installation on the target machine, but control of the graphical installation is handled by another system on the network. The RHEL installation program offers two VNC installation modes: Direct and Connect. Once a connection is established, the two modes do not differ. The mode you select depends on your environment.
- Direct mode
- In Direct mode, the RHEL installation program is configured to start on the target system and wait for a VNC viewer that is installed on another system before proceeding. As part of the Direct mode installation, the IP address and port are displayed on the target system. You can use the VNC viewer to connect to the target system remotely using the IP address and port, and complete the graphical installation.
- Connect mode
- In Connect mode, the VNC viewer is started on a remote system in listening mode. The VNC viewer waits for an incoming connection from the target system on a specified port. When the RHEL installation program starts on the target system, the system host name and port number are provided by using a boot option or a Kickstart command. The installation program then establishes a connection with the listening VNC viewer using the specified system host name and port number. To use Connect mode, the system with the listening VNC viewer must be able to accept incoming network connections.
8.2. Considerations
By default, the installation program has a VNC server included. Consider the following items when performing a remote RHEL installation using VNC:
VNC client application: A VNC client application is required to perform both a VNC Direct and Connect installation. VNC client applications are available in the repositories of most Linux distributions, and free VNC client applications are also available for other operating systems such as Windows. The following VNC client applications are available in RHEL:
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tigervncis independent of your desktop environment and is installed as part of thetigervncpackage. -
vinagreis part of the GNOME desktop environment and is installed as part of thevinagrepackage.
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Network and firewall:
- If the target system is not allowed inbound connections by a firewall, then you must use Connect mode or disable the firewall. Disabling a firewall can have security implications.
- If the system that is running the VNC viewer is not allowed incoming connections by a firewall, then you must use Direct mode, or disable the firewall. Disabling a firewall can have security implications. See the Security hardening document for more information about configuring the firewall.
- Custom Boot Options: You must specify custom boot options to start a VNC installation and the installation instructions might differ depending on your system architecture.
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VNC in Kickstart installations: You can use VNC-specific commands in Kickstart installations. Using only the
vnccommand runs a RHEL installation in Direct mode. Additional options are available to set up an installation using Connect mode.
