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Configure DHCP boot options

When you use Sophos Firewall as a DHCP server, you can configure it to distribute boot configuration information to DHCP clients.


DHCP options provide configuration information to DHCP clients. The options carry configuration parameters and other control information as tagged data items in the options field of a DHCP message. The data items represent the options specified by the vendor of the DHCP client.

Sophos Firewall supports all the specified DHCP options (1 to 255). For a complete list of the options, see DHCP options. Sophos Firewall supports the following standards:

  • RFC 2131: DHCP options and BOOTP vendor extensions
  • RFC 2132: Dynamic Host Configuration Protocol


This example shows how to configure DHCP options 66 and 67 to have Sophos Firewall distribute boot information to DHCP clients. This provides PXE clients with a TFTP server IP address and gives those clients the path to the file containing boot information. Here is the network information:

  • Sophos Firewall DHCP server interface:
  • TFTP server:
  • Boot file location: boot\x64\
  • DHCP clients: to

Network schema.

Configure the DHCP server

Configure Sophos Firewall as the DHCP server, specifying the IP addresses you want to lease to the DHCP clients, DNS settings, and boot options. Do the following:


For settings not mentioned, use the default values.

  1. Go to Network > DHCP > Server.
  2. Click Add.
  3. For General Settings, enter the following:

    Setting Value
    Name DHCP_boot_options
    Interface Port2 -
    Dynamic IP lease Start IP:
    End IP:

    Here's an example:

    Configure DHCP server.

  4. For DNS server, select Use device's DNS settings.

  5. For Boot options, enter the following:

    Setting Value
    Boot file boot\x64\

    Here's an example:

    Boot options.

  6. Click Save.

DHCP clients now receive TFTP server and boot file information as part of the DHCP configuration from Sophos Firewall. PXE clients can use this information to locate the TFTP server and download the boot file.

More information