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Prepare and request a custom ISO mount

Validate a public HTTPS image source, preserve its published checksum, and queue a custom ISO request for operator review.

Tungsto documentation · Updated · 3 min read

On this page
  1. Before you start
  2. Choose a verifiable image
  3. Check reachability and integrity
  4. Queue the mount request
  5. Troubleshoot and close the change
  6. Related resources

Before you start

  • A custom ISO from a trusted publisher with documented hardware and boot-mode compatibility.
  • A stable public HTTPS URL without embedded usernames, passwords, expiring cookies, or private-network addresses.
  • The publisher’s checksum obtained through a trustworthy channel.
  • A current off-server backup before booting any installer or recovery image.

Choose a verifiable image

Use an image intended for unattended or remote-console installation on physical hardware. Confirm architecture, UEFI or legacy boot support, storage-controller drivers, network drivers, and licensing. A URL that ends in .iso is not evidence that the content is safe or even an ISO.

Prefer an HTTPS address controlled by the image publisher. URLs using embedded credentials, localhost, local names or literal private addresses are rejected. A permitted URL is not a security or compatibility approval: the operator must verify the final destination, redirects, file size and checksum before mounting the image.

Check reachability and integrity

Check the response chain from a trusted workstation and save the publisher’s expected SHA-256 value. A HEAD response can confirm that the URL is reachable, but it does not prove that a later download will contain the same bytes. Download the image only if your security policy permits it, then compute its digest and compare every character with the publisher’s value.

  • Reject unexpected redirects, authentication pages, HTML responses, and changing filenames.
  • Give the operator the final resolved HTTPS URL, expected size, and checksum.
  • Do not place secrets in the query string; URLs may appear in action records and operational logs.
sh
curl --head --location --max-redirs 3 --proto '=https' --proto-redir '=https' https://downloads.example.net/rescue.iso
sha256sum rescue.iso

Queue the mount request

The expected account result is an ISO mount queued message. It is not proof that media was mounted. There is no action-status endpoint, no console URL response, and no unmount control in the current interface. Avoid creating repeated actions while waiting.

  1. Open Account > Servers and select the correct server.
  2. Paste the public HTTPS URL into Custom ISO URL.
  3. Select Mount ISO once and record the shortened queued action reference.
  4. Send the operator the server name, action reference, checksum, expected size, boot mode, and whether a one-time boot is required.
  5. Wait for an explicit confirmation before attempting to use the image through a delivered console session.

Troubleshoot and close the change

After use, ask the operator to detach the virtual media and restore the normal boot order. Verify that the installed system boots from local storage and that the expected network addresses return before considering the change complete.

ProblemCheckSafe response
URL rejectedHTTPS scheme, credentials, hostname, and literal addressMove the image to a suitable trusted public origin; do not weaken validation.
Queue accepted, no mediaAction reference and operator acknowledgementAsk the operator to fulfil or reject the request.
Image does not bootArchitecture, UEFI mode, image integrity, and virtual-media compatibilityCapture the console error and stop before altering disks.
Checksum differsSource, redirect chain, and published digestDo not mount or boot the file.