3.3. Preparing Installation Sources

As explained in Chapter 2, Downloading Red Hat Enterprise Linux, two basic types of media are available for Red Hat Enterprise Linux: a minimal boot image and a full installation image (also known as a binary DVD). If you downloaded the binary DVD and created a boot DVD-ROM or USB drive from it, you can proceed with the installation immediately, as this image contains everything you need to install the system.
However, if you use the minimal boot image, you must also configure an additional source of the installation. This is because the minimal boot image only contains the installation program itself and tools needed to boot your system and start the installation; it does not include the software packages to be installed on your system.
The full installation DVD ISO image can be used as the source for the installation. If your system will require additional software not provided by Red Hat, you should configure additional repositories and install these packages after the installation is finished. For information about configuring additional Yum repositories on an installed system, see the Red Hat Enterprise Linux 7 System Administrator's Guide.
The installation source can be any of the following:
  • DVD: You can burn the binary DVD ISO image onto a DVD and configure the installation program to install packages from this disk.
  • Hard drive: You can place the binary DVD ISO image on a hard drive and install packages from it.
  • Network location: You can copy the binary DVD ISO image or the installation tree (extracted contents of the binary DVD ISO image) to a network location accessible from the installation system and perform the installation over the network using the following protocols:
    • NFS: The binary DVD ISO image is placed into a Network File System (NFS) share.
    • HTTPS, HTTP or FTP: The installation tree is placed on a network location accessible over HTTP, HTTPS, or FTP.
When booting the installation from minimal boot media, you must always configure an additional installation source. When booting the installation from the full binary DVD, it is also possible to configure another installation source, but it is not necessary - the binary DVD ISO image itself contains all packages you need to install the system, and the installation program will automatically configure the binary DVD as the source.
You can specify an installation source in any of the following ways:

3.3.1. Installation Source on a DVD

You can burn the binary DVD ISO image onto a DVD and configure the installation program to install packages from this disk while booting the installation from another drive (for example, a minimal boot ISO on a USB flash drive). This procedure is the same as creating bootable optical media - see Section 3.1, “Making an Installation CD or DVD” for more information.
When using a DVD as an installation source, make sure the DVD is in the drive when the installation begins. The Anaconda installation program is not able to detect media inserted after the installation begins.

3.3.2. Installation Source on a Hard Drive

Hard drive installations use an ISO image of the binary installation DVD. To use a hard drive as the installation source, transfer the binary DVD ISO image to the drive and connect it to the installation system. Then, boot the Anaconda installation program.
You can use any type of hard drive accessible to the installation program, including USB flash drives. The binary ISO image can be in any directory of the hard drive, and it can have any name; however, if the ISO image is not in the top-level directory of the drive, or if there is more than one image in the top-level directory of the drive, you will be required to specify the image to be used. This can be done using a boot option, an entry in a Kickstart file, or manually in the Installation Source screen during a graphical installation.
A limitation of using a hard drive as the installation source is that the binary DVD ISO image on the hard drive must be on a partition with a file system which Anaconda can mount. These file systems are xfs, ext2, ext3, ext4, and vfat (FAT32). Note that on Microsoft Windows systems, the default file system used when formatting hard drives is NTFS, and the exFAT file system is also available; however, neither of these file systems can be mounted during the installation. If you are creating a hard drive or a USB drive to be used as an installation source on Microsoft Windows, make sure to format the drive as FAT32.

Important

The FAT32 file system does not support files larger than 4 GiB. Some Red Hat Enterprise Linux 7 installation media can be larger than that, which means you cannot copy them to a drive with this file system.
When using a hard drive or a USB flash drive as an installation source, make sure it is connected to the system when the installation begins. The installation program is not able to detect media inserted after the installation begins.

3.3.3. Installation Source on a Network

Placing the installation source on a network has the advantage of allowing you to install multiple systems from a single source, without having to connect and disconnect any physical media. Network-based installations can be especially useful when used together with a TFTP server, which allows you to boot the installation program from the network as well. This approach completely eliminates the need for creating physical media, allowing easy deployment of Red Hat Enterprise Linux on multiple systems at the same time. For further information about setting up a TFTP server, see Chapter 23, Preparing for a Network Installation.

3.3.3.1. Installation Source on an NFS Server

The NFS installation method uses an ISO image of the Red Hat Enterprise Linux binary DVD placed in a Network File System server's exported directory, which the installation system must be able to read. To perform an NFS-based installation, you will need another running system which will act as the NFS host.
For more information about NFS servers, see the Red Hat Enterprise Linux 7 Storage Administration Guide.
The following procedure is only meant as a basic outline of the process. The precise steps you must take to set up an NFS server will vary based on the system's architecture, operating system, package manager, service manager, and other factors. On Red Hat Enterprise Linux 7 systems, the procedure can be followed exactly as documented. For procedures describing the installation source creation process on earlier releases of Red Hat Enterprise Linux, see the appropriate Installation Guide for that release.

Procedure 3.4. Preparing for Installation Using NFS

  1. Install the nfs-utils package by running the following command as root: 
    # yum install nfs-utils
  2. Copy the full Red Hat Enterprise Linux 7 binary DVD ISO image to a suitable directory on the NFS server. For example, you can create directory /rhel7-install/ for this purpose and save the ISO image here.
  3. Open the /etc/exports file using a text editor and add a line with the following syntax: 
    /exported_directory/ clients
    Replace /exported_directory/ with the full path to the directory holding the ISO image. Instead of clients, use the host name or IP address of the computer which is to be installed from this NFS server, the subnetwork from which all computers are to have access the ISO image, or the asterisk sign (*) if you want to allow any computer with network access to the NFS server to use the ISO image. See the exports(5) man page for detailed information about the format of this field.
    The following is a basic configuration which makes the /rhel7-install/ directory available as read-only to all clients: 
    /rhel7-install *
  4. Save the /etc/exports file after finishing the configuration and exit the text editor.
  5. Start the nfs service: 
    # systemctl start nfs.service
    If the service was already running before you changed the /etc/exports file, enter the following command instead, in order for the running NFS server to reload its configuration: 
    # systemctl reload nfs.service
After completing the procedure above, the ISO image is accessible over NFS and ready to be used as an installation source.
When configuring the installation source before or during the installation, use nfs: as the protocol, the server's host name or IP address, the colon sign (:), and the directory holding the ISO image. For example, if the server's host name is myserver.example.com and you have saved the ISO image in /rhel7-install/, specify nfs:myserver.example.com:/rhel7-install/ as the installation source.

3.3.3.2. Installation Source on an HTTP, HTTPS or FTP Server

This installation method allows for a network-based installation using an installation tree, which is a directory containing extracted contents of the binary DVD ISO image and a valid .treeinfo file. The installation source is accessed over HTTP, HTTPS, or FTP.
For more information about HTTP and FTP servers, see the Red Hat Enterprise Linux 7 System Administrator's Guide.
The following procedure is only meant as a basic outline of the process. The precise steps you must take to set up an FTP server will vary based on the system's architecture, operating system, package manager, service manager, and other factors. On Red Hat Enterprise Linux 7 systems, the procedure can be followed exactly as documented. For procedures describing the installation source creation process on earlier releases of Red Hat Enterprise Linux, see the appropriate Installation Guide for that release.

Procedure 3.5. Preparing Installation Using HTTP or HTTPS

  1. Install the httpd package by running the following command as root: 
    # yum install httpd
    An HTTPS server needs additional configuration. For detailed information, see section Setting Up an SSL Server in the Red Hat Enterprise Linux 7 System Administrator's Guide. However, HTTPS is not necessary in most cases, because no sensitive data is sent between the installation source and the installer, and HTTP is sufficient.

    Warning

    If your Apache web server configuration enables SSL security, make sure to only enable the TLSv1 protocol, and disable SSLv2 and SSLv3. This is due to the POODLE SSL vulnerability (CVE-2014-3566). See https://access.redhat.com/solutions/1232413 for details.

    Important

    If you decide to use HTTPS and the server is using a self-signed certificate, you must boot the installer with the noverifyssl option.
  2. Copy the full Red Hat Enterprise Linux 7 binary DVD ISO image to the HTTP(S) server.
  3. Mount the binary DVD ISO image, using the mount command, to a suitable directory: 
    # mount -o loop,ro -t iso9660 /image_directory/image.iso /mount_point/
    Replace /image_directory/image.iso with the path to the binary DVD ISO image, and /mount_point/ with the path to the directory in which you want the content of the ISO image to appear. For example, you can create directory /mnt/rhel7-install/ for this purpose and use that as the parameter of the mount command.
  4. Copy the files from the mounted image to the HTTP server root. 
    # cp -r /mnt/rhel7-install/ /var/www/html/
    This command creates the /var/www/html/rhel7-install/ directory with the content of the image.
  5. Start the httpd service: 
    # systemctl start httpd.service
After completing the procedure above, the installation tree is accessible and ready to be used as the installation source.
When configuring the installation source before or during the installation, use http:// or https:// as the protocol, the server's host name or IP address, and the directory in which you have stored the files from the ISO image, relative to the HTTP server root. For example, if you are using HTTP, the server's host name is myserver.example.com, and you have copied the files from the image to /var/www/html/rhel7-install/, specify http://myserver.example.com/rhel7-install/ as the installation source.

Procedure 3.6. Preparing for Installation Using FTP

  1. Install the vsftpd package by running the following command as root: 
    # yum install vsftpd
  2. Optionally, open the /etc/vsftpd/vsftpd.conf configuration file in a text editor, and edit any options you want to change. For available options, see the vsftpd.conf(5) man page. The rest of this procedure assumes that default options are used; notably, to follow the rest of the procedure, anonymous users of the FTP server must be permitted to download files.

    Warning

    If you configured SSL/TLS security in your vsftpd.conf file, make sure to only enable the TLSv1 protocol, and disable SSLv2 and SSLv3. This is due to the POODLE SSL vulnerability (CVE-2014-3566). See https://access.redhat.com/solutions/1234773 for details.
  3. Copy the full Red Hat Enterprise Linux 7 binary DVD ISO image to the FTP server.
  4. Mount the binary DVD ISO image, using the mount command, to a suitable directory: 
    # mount -o loop,ro -t iso9660 /image_directory/image.iso /mount_point
    Replace /image_directory/image.iso with the path to the binary DVD ISO image, and /mount_point with the path to the directory in which you want the content of the ISO image to appear. For example, you can create directory /mnt/rhel7-install/ for this purpose and use that as the parameter of the mount command.
  5. Copy the files from the mounted image to the FTP server root: 
    # cp -r /mnt/rhel7-install/ /var/ftp/
    This command creates the /var/ftp/rhel7-install/ directory with the content of the image.
  6. Start the vsftpd service: 
    # systemctl start vsftpd.service
    If the service was already running before you changed the /etc/vsftpd/vsftpd.conf file, restart it to ensure the edited file is loaded. To restart, execute the following command: 
    # systemctl restart vsftpd.service
After completing the procedure above, the installation tree is accessible and ready to be used as the installation source.
When configuring the installation source before or during the installation, use ftp:// as the protocol, the server's host name or IP address, and the directory in which you have stored the files from the ISO image, relative to the FTP server root. For example, if the server's host name is myserver.example.com and you have copied the files from the image to /var/ftp/rhel7-install/, specify ftp://myserver.example.com/rhel7-install/ as the installation source.

3.3.3.3. Firewall Considerations for Network-based Installations

When using a network-based installation source, make sure that your firewall allows the server you are installing to access the remote installation source. The following table shows which ports must be open for each type of network-based installation

Table 3.1. Ports Used by Network Protocols

Protocol used Ports to open
FTP 21
HTTP 80
HTTPS 443
NFS 2049, 111, 20048
TFTP 69
For information about opening specific firewall ports, see the Red Hat Enterprise Linux 7 Security Guide.