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bootp(1M)							     bootp(1M)

NAME    [Toc]    [Back]

     bootp - server for	Internet Bootstrap Protocol

SYNOPSIS    [Toc]    [Back]

     /usr/etc/bootp [ -d ] [ -f	]

DESCRIPTION    [Toc]    [Back]

     bootp is a	server that supports the Internet Bootstrap Protocol (BOOTP).
     This protocol is designed to allow	a (possibly diskless) client machine
     to	determine its own Internet address, the	address	of a boot server, and
     the name of an appropriate	boot file to be	loaded and executed.  BOOTP
     does not provide the actual transfer of the boot file, which is typically
     done with a simple	file transfer protocol such as TFTP.  A	detailed
     protocol specification for	BOOTP is contained in RFC 951, which is
     available from the	Network	Information Center.

     The BOOTP protocol	uses UDP/IP as its transport mechanism.	 The BOOTP
     server receives service requests at the UDP port indicated	in the
     ``bootp'' service description contained in	the file /etc/services (see
     services(4)).  The	BOOTP server is	started	by inetd(1M), as configured in
     the inetd.conf file.

     The basic operation of the	BOOTP protocol is a single packet exchange as

     1.	 The booting client machine broadcasts a BOOTP request packet to the
	 BOOTP server UDP port,	using a	UDP broadcast or the equivalent
	 thereof.  The request packet includes the following information:

	 requester's network hardware address
	 requester's Internet address (optional)
	 desired server's name (optional)
	 boot filename (optional)

     2.	 All the BOOTP servers on the same network as the client machine
	 receive the client's request.	If the client has specified a
	 particular server, then only that server responds.

     3.	 The server looks up the requester in its configuration	file by
	 Internet address or network hardware address, in that order of
	 preference.  (The BOOTP configuration file is described below.)  If
	 the Internet address was not specified	by the requester and a
	 configuration record is not found, the	server looks in	the
	 /etc/ethers file (see ethers(4)) for an entry with the	client's
	 network hardware address.  If an entry	is found, the server checks
	 the hostname of that entry against the	/etc/hosts file	(see hosts(4))
	 in order to complete the network hardware address to Internet address
	 mapping.  If the BOOTP	request	does not include the client's Internet
	 address and the server	is unable to translate the client's network
	 hardware address into an Internet address by either of	the two
	 methods described, the	server does not	respond	to the request.

									Page 1

bootp(1M)							     bootp(1M)

     4.	 The server performs name translation on the boot filename requested
	 and then checks for the presence of that file.	 If the	file is
	 present, then the server sends	a response packet to the requester
	 that includes the following information:

	 requester's Internet address
	 server's Internet address
	 Internet address of a gateway to the server
	 server's name
	 vendor-specific information (not defined by the protocol)

	 If the	boot file is missing, the server returns a response packet
	 with a	null filename but only if the request was specifically
	 directed to that server.  The pathname	translation is:	 if the	boot
	 filename is rooted, use it as is; else	concatenate the	root of	the
	 boot subtree, as specified by the BOOTP configuration file, followed
	 by the	filename supplied by the requester, followed by	a period and
	 the requester's hostname.  If that file is not	present, remove	the
	 trailing period and hostname and try again.  If no boot filename is
	 requested, use	the default boot file for that host from the
	 configuration table.  If there	is no default specified	for that host,
	 use the general default boot filename,	first with .hostname as	a
	 suffix	and then without.  Note	that tftpd(1M) must be configured to
	 allow access to the boot file (see the	tftpd(1M) reference page for

   Options    [Toc]    [Back]
     The -d option causes bootp	to generate debugging messages.	 All messages
     from bootp	go through syslogd(1M),	the system logging daemon.

     The -f option enables the forwarding function of bootp.  Refer to the
     following section,	``Booting through Gateways,'' for an explanation.

   Bootp Configuration File    [Toc]    [Back]
     In	order to perform its name translation and address resolution
     functions,	bootp requires configuration information that it gets from an
     ASCII file	called /etc/bootptab and from other system configuration files
     like /etc/ethers and /etc/hosts.  Here is a sample	bootptab file:

	  # /etc/bootptab:  database for bootp server
	  # Blank lines	and lines beginning with '#' are ignored.
	  # Root of boot subtree:

	  # Default bootfile:


	  # The	remainder of this file contains	one line per client

									Page 2

bootp(1M)							     bootp(1M)

	  # interface with the information shown by the	table headings
	  # below. The 'host' name is also tried as a suffix for the
	  # 'bootfile' when searching the boot directory.
	  # (e.g., bootfile.host)
	  # host    htype     haddr	     iaddr	    bootfile

	  IRIS	 1  01:02:03:8a:8b:8c      unix

     The fields	of each	line can be separated by variable amounts of white
     space (blanks and tabs).  The first section, up to	the line beginning %%,
     defines the place where bootp looks for boot files	when the client
     requests a	boot file using	a nonrooted pathname.  The second section of
     the file is used for mapping client network hardware addresses into
     Internet addresses.  Up to	512 hosts can be specified.  The htype field
     should always have	a value	of 1 for now; this indicates that the hardware
     address is	a 48-bit Ethernet address.  The	haddr field is the Ethernet
     address of	the system in question expressed as six	hexadecimal bytes
     separated by colons.  The iaddr field is the 32-bit Internet address of
     the system	expressed in standard Internet dot notation (see inetd(3N)).
     Each line in the second section can also specify a	default	boot file for
     each specific host.  In the example above,	if the host called unixbox
     makes a BOOTP request with	no boot	file specified,	the server selects the
     first of the following that it finds:


     The length	of the boot filename must not exceed 127 characters.

     It	is not necessary to create a record for	every potential	client in the
     bootptab file.  The only constraint is that bootp responds	only to	a
     request from a client if it can deduce the	client's Internet address.
     There are three ways that this can	happen:

     o	The client already knows its Internet address and includes it in the
	BOOTP request packet.
     o	There is an entry in /etc/bootptab that	matches	the client's network
	hardware address.
     o	There are entries in the /etc/ethers and /etc/hosts files (or their
	NIS equivalents) that allow the	client's network hardware address to
	be translated into an Internet address.

   Booting through Gateways    [Toc]    [Back]
     Since the BOOTP request is	distributed using a UDP	broadcast, it is only
     received by other hosts on	the same network as the	client.	 In some cases
     the client	may wish to boot from a	host on	another	network.  This can be
     accomplished by using the forwarding function of BOOTP servers on the
     local network.  To	use BOOTP forwarding, there must be a bootp process
     running in	a gateway machine on the local network.	 A gateway machine is
     simply a machine with more	than one network interface board.  The gateway
     bootp must	be invoked with	the -f option to activate forwarding.  Such a

									Page 3

bootp(1M)							     bootp(1M)

     forwarding	bootp resends any BOOTP	request	it receives that asks for a
     specific host by name, if that host is on a different network from	the
     client that sent the request.  The	BOOTP server forwards the packet using
     the full routing capabilities of the underlying IP	layer in the kernel,
     so	the forwarded packet is	automatically routed to	the requested BOOTP
     server if the kernel routing tables contain a route to the	destination

DIAGNOSTICS    [Toc]    [Back]

     The BOOTP server logs messages using the system logging daemon,
     syslogd(1M).  The actual disposition of these messages depends on the
     configuration of syslogd on the machine in	question.  Consult syslogd(1M)
     for further information.

     bootp can produce the following messages:

     'get interface config' ioctl failed (message)
     'get interface netmask' ioctl failed (message)
     getsockname failed	(message)
     forwarding	failed (message)
     send failed (message)
     set arp ioctl failed
	  Each of the above messages means that	a system call has returned an
	  error	unexpectedly.  Such errors usually cause bootp to terminate.
	  The message is the appropriate standard system error message.

     less than two interfaces, -f flag ignored
	  Warning only (debug mode).  Means that the -f	option was specified
	  on a machine that is not a gateway.  Forwarding only works on

     request for unknown host xxx from yyy
	  Information only.  A BOOTP request was received asking for host xxx,
	  but that host	is not in the host database.  The request was
	  generated by yyy, which can be given as a hostname or	an Internet

     request from xxx for 'fff'
	  Information only.  bootp logs	each request for a boot	file.  The
	  host xxx has requested boot file fff.

     can't access boot file fff	(message)
	  A request has	been received for the boot file	fff, but that file is
	  not accessible.

     reply boot	filename fff too long
	  The filename length fff exceeds the BOOTP protocol limit of 127

     reply boot	file fff
	  Information only.  bootp has selected	the file fff as	the boot file
	  to satisfy a request.

									Page 4

bootp(1M)							     bootp(1M)

     can't reply to dd.dd.dd.dd	(unknown net)
	  This bootp has generated a response to a client and is trying	to
	  send the response directly to	the client (that is, the request did
	  not get forwarded by another bootp), but none	of the network
	  interfaces on	this machine is	on the same directly connected network
	  as the client	machine.

     reply: can't find net for dd.dd.dd.dd
	  The server is	acting as BOOTP	forwarder and has received a datagram
	  with a client	address	that is	not on a directly connected network.

     can't open	/etc/bootptab
	  The bootp configuration file is missing or has wrong permissions.

     (re)reading /etc/bootptab
	  Information only.  bootp checks the modification date	of the
	  configuration	file on	the receipt of each request and	rereads	it if
	  it has been modified since the last time it was read.

     bad hex address: xxx at line nnn of bootptab
     bad internet address: sss at line nnn of bootptab
     string truncated: sss, on line nnn	of bootptab
	  These	messages mean that the format of the BOOTP configuration file
	  is not valid.

     'hosts' table length exceeded
	  There	are too	many lines in the second section of the	BOOTP
	  configuration	file.  The current limit is 512.

     can't allocate memory
	  A call to malloc(3C) failed.

     gethostbyname(sss)	failed (message)
	  A call to gethostbyname(3N) with the argument	sss has	failed.

     gethostbyaddr(dd.dd.dd.dd)	failed (message)
	  A call to gethostbyaddr(3N) with the argument	dd.dd.dd.dd has

SEE ALSO    [Toc]    [Back]

     dhcp_bootp(1M), inetd(1M),	rarpd(1M), syslogd(1M),	tftpd(1M), ethers(4),
     hosts(4), services(4).

									PPPPaaaaggggeeee 5555
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