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Install Junos OS on SRX300 Line of Firewalls from the Boot Loader Using a TFTP Server

Learn how to install Junos OS on SRX Series Firewalls using a TFTP server from the boot loader. This process includes prerequisites, U-Boot updates, and step-by-step installation procedures.

The SRX300 line of Firewalls are shipped with Junos OS loaded on the primary boot device. During Junos OS installation from the bootloader, the device retrieves the Junos OS package from a TFTP server. The internal media are then formatted, and the Junos OS image is installed.

You can use the bootloader to:

  • Install Junos OS on the device for the first time.

  • Recover the system from a file system corruption. You can install Junos OS from a TFTP server by using only the first onboard Ethernet interface. Installation from the loader-over-TFTP method does not work reliably over slow speeds or large latency networks.

Before you begin

Upgrade or downgrade the SRX300 Line of Firewall from Junos OS Release 24.4R1 using the boot loader. After rebooting, the device enters an amnesiac state. Therefore, before installing the software, you must save the configuration file so that you can easily reconfigure the device by using the console port.

Also, before upgrading from either Junos OS Release 23.4R2-S3 or 24.2R2 to Junos OS Release 24.4R1 for SRX300 Line of Firewalls, complete the following:

  1. Upgrade the U-boot software to at least version 3.15. After you install either Junos OS Release 23.4R2-S3 or 24.2R2, the Junos OS image contains the latest bootloader binaries in these paths: /boot/uboot and /boot/veloader. You can upgrade the U-Boot software and veloader software as follows:

    1. From the CLI prompt, enter the start shell command.

    2. From the shell prompt, update the U-Boot software with the bootupgrade -u /boot/uboot command.

    3. From the shell prompt, update the veloader with the bootupgrade -l /boot/veloader -x command.

    4. Reboot the device. Once the device is back up, you can use the Trivial File Transfer Protocol (TFTP) to upgrade to Junos OS Release 24.4R1.

  2. Upgrade the bootloader to a build from the year 2023 or later. During the boot process, the bootloader reveals the build date. In the following example, you can see the build date as May 23, 2023.

  3. Verify these prerequisites:

    • You have access to the TFTP server with the Junos OS package to be installed.

    • The TFTP server supports BOOTP or DHCP. If the TFTP server does not support BOOTP or DHCP, you must set the environment variables before installing the software from the TFTP server.

    • Functional network connectivity exists between the device and the TFTP server over the first onboard Ethernet interface.

To install the Junos OS image on the internal media of the device:

  1. Connect to the device by using the console connection and access the U-Boot prompt.
  2. Reboot the device.

    The following message and prompt appear:

  3. Press the space bar to stop the automatic boot process.

    The => U-Boot prompt appears.

  4. Configure the environment variables listed in Table 1.
    Table 1: Environment Variables Settings

    Environment Variables

    Description

    gatewayip

    IP address of the SRX Series Firewall

    ipaddr

    IP address of the SRX Series Firewall

    netmask

    Network mask

    serverip

    IP address of the TFTP server

    You can see the configured environment variables in this example:

  5. Reboot the system using the reset command.
  6. Reboot the device.

    The following message and prompt appear:

    Loading /boot/defaults/loader.conf

    Hit [Enter] to boot immediately, or space bar for command prompt.

  7. Press the space bar to access the loader prompt (loader>).

    At the loader> prompt, enter:

    The URL has the format tftp://tftp-serveripaddress/package where the URL path is relative to the TFTP server’s TFTP root directory.

When this command is executed:

  1. The system downloads the Junos OS package from the TFTP server.

  2. The system formats the internal media.

  3. The system installs the Junos OS package on the formatted internal media.

After you install Junos OS, the device boots from the internal media. After the system boots up with Junos OS Release, you must upgrade the U-boot and boot loader immediately.