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PXEBOOT(8)		  BSD System Manager's Manual		    PXEBOOT(8)

     pxeboot --	Preboot	Execution Environment (PXE) bootloader

     The pxeboot bootloader is a modified version of the system	third-stage
     bootstrap loader(8) configured to run under Intel's Preboot Execution En-
     vironment (PXE) system.  PXE is a form of smart boot ROM, built into In-
     tel EtherExpress Pro/100 and 3Com 3c905c Ethernet cards, and Ethernet-
     equipped Intel motherboards.  PXE supports	DHCP configuration and pro-
     vides low-level NIC access	services.

     The DHCP client will set a	DHCP user class	named FreeBSD to allow flexi-
     ble configuration of the DHCP server.

     The pxeboot bootloader retrieves the kernel, modules, and other files ei-
     ther via NFS over UDP or by TFTP, selectable through compile-time op-
     tions.  In	combination with a memory file system image or NFS-mounted
     root file system, pxeboot allows for easy,	EEPROM-burner free construc-
     tion of diskless machines.

     The pxeboot binary	is loaded just like any	other boot file, by specifying
     it	in the DHCP server's configuration file.  Below	is a sample configura-
     tion for the ISC DHCP v2 server:

	   option domain-name "";
	   option routers;
	   option subnet-mask;
	   option broadcast-address;
	   option domain-name-servers;
	   server-name "DHCPserver";

	   default-lease-time 120;
	   max-lease-time 120;

	   subnet netmask {
		  filename "pxeboot";
		  if exists user-class and option user-class = "FreeBSD" {
		       option root-path	"tftp://";

     pxeboot recognizes	next-server and	option root-path directives as the
     server and	path to	NFS mount for file requests, respectively, or the
     server to make TFTP requests to.  Note that pxeboot expects to fetch
     /boot/loader.rc from the specified	server before loading any other	files.

     Valid option root-path Syntax is the following

     /path		 path to the root filesystem on	the NFS	server

     ip:/path		 path to the root filesystem on	the NFS	server ip

     nfs:/path		 path to the root filesystem on	the NFS	server

     nfs://ip/path	 path to the root filesystem on	the NFS	server ip

     tftp:/path		 path to the root filesystem on	the TFTP server

     tftp://ip/path	 path to the root filesystem on	the TFTP server	ip

     pxeboot defaults to a conservative	1024 byte NFS data packet size.	 This
     may be changed by setting the nfs.read_size variable in
     /boot/loader.conf.	 Valid values range from 1024 to 16384 bytes.

     In	all other respects, pxeboot acts just like loader(8).

     As	PXE is still in	its infancy, some firmware versions may	not work prop-
     erly.  The	pxeboot	bootloader has been extensively	tested on version 0.99
     of	Intel firmware;	pre-release versions of	the newer 2.0 firmware are
     known to have problems.  Check with the device's manufacturer for their
     latest stable release.

     For further information on	Intel's	PXE specifications and Wired for Man-
     agement (WfM) systems, see


     The pxeboot bootloader first appeared in FreeBSD 4.1.

     The pxeboot bootloader was	written	by John	Baldwin	<> and
     Paul Saab <>.  This manual page was written by Doug White

BSD				 May 27, 2017				   BSD


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