SH NAME
bootptab \- Internet Bootstrap Protocol server database
SH DESCRIPTION
The
I bootptab
file is the configuration database file for
IR bootpd ,
the Internet Bootstrap Protocol server.
Its format is similar to that of
IR capfile (5)
in which two-character case-sensitive tag symbols are used to
represent host parameters. These parameter declarations are separated by
colons (:), with a general format of:
PP
I " hostname:tg=value:tg=value:tg=value:"
PP
where
I hostname
is the actual name of a bootp client (or a "dummy entry"), and
I tg
is a two-character tag symbol. Replies are returned to clients
only if an entry with the client's Ethernet or IP address exists
in the
I booptab
file. Dummy entries have an invalid hostname
(one with a "." as the first character) and are used to provide
default values used by other entries via the
B tc=.dummy-entry
mechanism. Most tags must be followed by an equal sign
and a value as above. Some may also appear in a boolean form with no
value (i.e.
RI : tg :).
The currently recognized tags are:
PP
br
bf Bootfile
br
bs Bootfile size in 512-octet blocks
br
cs Cookie server address list
br
df Merit dump file
br
dn Domain name
br
ds Domain name server address list
br
ef Extension file
br
gw Gateway address list
br
ha Host hardware address
br
hd Bootfile home directory
br
hn Send client's hostname to client
br
ht Host hardware type (see Assigned Numbers RFC)
br
im Impress server address list
br
ip Host IP address
br
lg Log server address list
br
lp LPR server address list
br
ns IEN-116 name server address list
br
nt NTP (time) Server (RFC 1129)
br
ra Reply address override
br
rl Resource location protocol server address list
br
rp Root path to mount as root
br
sa TFTP server address client should use
br
sm Host subnet mask
br
sw Swap server address
br
tc Table continuation (points to similar "template" host entry)
br
td TFTP root directory used by "secure" TFTP servers
br
to Time offset in seconds from UTC
br
ts Time server address list
br
vm Vendor magic cookie selector
br
yd YP (NIS) domain name
br
ys YP (NIS) server address
PP
There is also a generic tag,
RI T n ,
where
I n
is an RFC1084 vendor field tag number. Thus it is possible to immediately
take advantage of future extensions to RFC1084 without being forced to modify
I bootpd
first. Generic data may be represented as either a stream of hexadecimal
numbers or as a quoted string of ASCII characters. The length of the generic
data is automatically determined and inserted into the proper field(s) of the
RFC1084-style bootp reply.
PP
The following tags take a whitespace-separated list of IP addresses:
BR cs ,
BR ds ,
BR gw ,
BR im ,
BR lg ,
BR lp ,
BR ns ,
BR nt ,
BR ra ,
BR rl ,
and
BR ts .
The
BR ip ,
BR sa ,
BR sw ,
BR sm ,
and
B ys
tags each take a single IP address.
All IP addresses are specified in standard Internet "dot" notation
and may use decimal, octal, or hexadecimal numbers
(octal numbers begin with 0, hexadecimal numbers begin with '0x' or '0X').
Any IP addresses may alternatively be specified as a hostname, causing
I bootpd
to lookup the IP address for that host name using gethostbyname(3).
If the
B ip
tag is not specified,
I bootpd
will determine the IP address using the entry name as the host name.
(Dummy entries use an invalid host name to avoid automatic IP lookup.)
PP
The
B ht
tag specifies the hardware type code as either an unsigned decimal, octal, or
hexadecimal integer or one of the following symbolic names:
B ethernet
or
B ether
for 10Mb Ethernet,
B ethernet3
or
B ether3
for 3Mb experimental Ethernet,
BR ieee802 ,
BR tr ,
or
B token-ring
for IEEE 802 networks,
B pronet
for Proteon ProNET Token Ring, or
BR chaos ,
BR arcnet ,
or
B ax.25
for Chaos, ARCNET, and AX.25 Amateur Radio networks, respectively.
The
B ha
tag takes a hardware address which may be specified as a host name
or in numeric form. Note that the numeric form
I must
be specified in hexadecimal; optional periods and/or a leading '0x' may be
included for readability. The
B ha
tag must be preceded by the
B ht
tag (either explicitly or implicitly; see
B tc
below).
If the hardware address is not specified and the type is specified
as either "ethernet" or "ieee802", then
I bootpd
will try to determine the hardware address using ether_hostton(3).
PP
The hostname, home directory, and bootfile are ASCII strings which may be
optionally surrounded by double quotes ("). The client's request and the
values of the
B hd
and
B bf
symbols determine how the server fills in the bootfile field of the bootp
reply packet.
PP
If the
B bf
option is specified, its value is copied into the reply packet.
Otherwise, the name supplied in the client request is used.
If the
B hd
option is specified, its value is prepended to the
boot file in the reply packet, otherwise the path
supplied in the client request is used.
The existence of the boot file is NOT verified by
I bootpd
because the boot file may be on some other machine.
PP
The
B bs
option specified the size of the boot file.
It can be written as
BR bs =auto
which causes
I bootpd
to determine the boot file size automatically.
PP
Some newer versions of
I tftpd
provide a security feature to change their root directory using
the
IR chroot (2)
system call.
The
B td
tag may be used to inform
I bootpd
of this special root directory used by
IR tftpd .
(One may alternatively use the
I bootpd
"-c chdir" option.)
The
B hd
tag is actually relative to the root directory specified by the
B td
tag.
For example, if the real absolute path to your BOOTP client bootfile is
/tftpboot/bootfiles/bootimage, and
IR tftpd
uses /tftpboot as its "secure" directory, then specify the following in
IR bootptab :
PP
br
:td=/tftpboot:hd=/bootfiles:bf=bootimage:
PP
If your bootfiles are located directly in /tftpboot, use:
PP
br
:td=/tftpboot:hd=/:bf=bootimage:
PP
The
B sa
tag may be used to specify the IP address of the particular TFTP server
you wish the client to use. In the absence of this tag,
I bootpd
will tell the client to perform TFTP to the same machine
I bootpd
is running on.
PP
The time offset
B to
may be either a signed decimal integer specifying the client's
time zone offset in seconds from UTC, or the keyword
B auto
which uses the server's time zone offset. Specifying the
B to
symbol as a boolean has the same effect as specifying
B auto
as its value.
PP
The bootfile size
B bs
may be either a decimal, octal, or hexadecimal integer specifying the size of
the bootfile in 512-octet blocks, or the keyword
B auto
which causes the server to automatically calculate the bootfile size at each
request. As with the time offset, specifying the
B bs
symbol as a boolean has the same effect as specifying
B auto
as its value.
PP
The vendor magic cookie selector (the
B vm
tag) may take one of the following keywords:
B auto
(indicating that vendor information is determined by the client's request),
B rfc1048
or
B rfc1084
(which always forces an RFC1084-style reply), or
B cmu
(which always forces a CMU-style reply).
PP
The
B hn
tag is strictly a boolean tag; it does not take the usual equals-sign and
value. It's presence indicates that the hostname should be sent to RFC1084
clients.
I Bootpd
attempts to send the entire hostname as it is specified in the configuration
file; if this will not fit into the reply packet, the name is shortened to
just the host field (up to the first period, if present) and then tried.
In no case is an arbitrarily-truncated hostname sent (if nothing reasonable
will fit, nothing is sent).
PP
Often, many host entries share common values for certain tags (such as name
servers, etc.). Rather than repeatedly specifying these tags, a full
specification can be listed for one host entry and shared by others via the
B tc
(table continuation) mechanism.
Often, the template entry is a dummy host which doesn't actually exist and
never sends bootp requests. This feature is similar to the
B tc
feature of
IR capfile (5) .
Note that
I bootpd
allows the
B tc
tag symbol to appear anywhere in the host entry, unlike
I capfile
which requires it to be the last tag. Information explicitly specified for a
host always overrides information implied by a
B tc
tag symbol, regardless of its location within the entry. The
value of the
B tc
tag may be the hostname or IP address of any host entry
previously listed in the configuration file.
PP
Sometimes it is necessary to delete a specific tag after it has been inferred
via
BR tc .
This can be done using the construction
IB tag @
which removes the effect of
I tag
as in
IR capfile (5).
For example, to completely undo an IEN-116 name server specification, use
":ns@:" at an appropriate place in the configuration entry. After removal
with
BR @ ,
a tag is eligible to be set again through the
B tc
mechanism.
PP
Blank lines and lines beginning with "#" are ignored in the configuration
file. Host entries are separated from one another by newlines; a single host
entry may be extended over multiple lines if the lines end with a backslash
(\\). It is also acceptable for lines to be longer than 80 characters. Tags
may appear in any order, with the following exceptions: the hostname must be
the very first field in an entry, and the hardware type must precede the
hardware address.
PP
An example
I /etc/bootptab
file follows:
PP
nf
# Sample bootptab file (domain=andrew.cmu.edu)
# Special domain name server and option tags for next host
butlerjct:ha=08002001560D:ds=128.2.13.42:\\
:T37=0x12345927AD3BCF:\\
:T99="Special ASCII string":\\
:tc=.default:
