Table of Contents

UUID setting

Name

  uuid

Details

Type UUID
DHCP option number 971)
ISC dhcpd syntax not applicable

Examples

Display the system UUID

  iPXE> show uuid
  smbios/uuid:uuid = 86a9f546-d31b-4ba2-9bbb-303b61bcf8d1

Fetch a boot script based on the system UUID

  iPXE> chain http://boot.ipxe.org/demo/boot.php?uuid=${uuid}

Description

Contains the system UUID, which should be a globally unique and permanent identifier for the system. The system UUID is read from the SMBIOS information.

See also

Notes

iPXE will normally send the system UUID as part of option 97 in all DHCP requests. If you need to prevent this, you can override the system UUID with an invalid value. For example: 

  iPXE> set uuid:string INVALID
  iPXE> dhcp                      # Option 97 will not be present in the DHCP request

SMBIOS versions 2.6 and newer store the UUID in a partially byte-swapped format. iPXE will handle the byte swapping automatically. You can get the raw unswapped bytes using the hexraw setting type. For example: 

  iPXE> show uuid
  smbios/uuid:uuid = b78bca22-4ea4-4d0c-9efd-e3c9a210ac79
  
  iPXE> show uuid:hexraw
  smbios/uuid:hexraw = 22ca8bb7a44e0c4d9efde3c9a210ac79

If you need to check whether or not your system has a byte-swapped UUID, you can test this using a script fragment such as: 

  set uuidcheck:uuid ${uuid:hexraw}
  iseq ${uuidcheck} ${uuid} || echo SMBIOS is version 2.6 or higher
1)
DHCP option 97 contains a single zero byte followed by the 16-byte system UUID