MAN page from Old RedHat 5.X bootp-2.4.3-5.i386.rpm

BOOTPTAB

Section: File Formats (5)
Updated: October 31, 1991
Index

NAME

bootptab - Internet Bootstrap Protocol server database

DESCRIPTION

Thebootptabfile is the configuration database file forbootpd,the Internet Bootstrap Protocol server.It's format is similar to that oftermcap(5)in which two-character case-sensitive tag symbols are used torepresent host parameters. These parameter declarations are separated bycolons (:), with a general format of:

hostname:tg=value. . . :tg=value. . . :tg=value. . . .

where
hostnameis the actual name of a bootp client (or a "dummy entry"), andtgis a two-character tag symbol. Dummy entries have an invalid hostname(one with a "." as the first character) and are used to providedefault values used by other entries via thetc=.dummy-entrymechanism. Most tags must be followed by an equals-signand a value as above. Some may also appear in a boolean form with novalue (i.e.:tg:).The currently recognized tags are:

       bf      Bootfile

       bs      Bootfile size in 512-octet blocks

       cs      Cookie server address list

       df      Merit dump file

       dn      Domain name

       ds      Domain name server address list

       ef      Extension file

       gw      Gateway address list

       ha      Host hardware address

       hd      Bootfile home directory

       hn      Send client's hostname to client

       ht      Host hardware type (see Assigned Numbers RFC)

       im      Impress server address list

       ip      Host IP address

       lg      Log server address list

       lp      LPR server address list

       ns      IEN-116 name server address list

       nt      NTP (time) Server (RFC 1129)

       ra      Reply address override

       rl      Resource location protocol server address list

       rp      Root path to mount as root

       sa      TFTP server address client should use

       sm      Host subnet mask

       sw      Swap server address

       tc      Table continuation (points to similar "template" host entry)

       td      TFTP root directory used by "secure" TFTP servers

       to      Time offset in seconds from UTC

       ts      Time server address list

       vm      Vendor magic cookie selector

       yd      YP (NIS) domain name

       ys      YP (NIS) server address

There is also a generic tag,Tn,wherenis an RFC1084 vendor field tag number. Thus it is possible to immediatelytake advantage of future extensions to RFC1084 without being forced to modifybootpdfirst. Generic data may be represented as either a stream of hexadecimalnumbers or as a quoted string of ASCII characters. The length of the genericdata is automatically determined and inserted into the proper field(s) of theRFC1084-style bootp reply.

The following tags take a whitespace-separated list of IP addresses:cs,ds,gw,im,lg,lp,ns,nt,ra,rl,andts.Theip,sa,sw,sm,andystags each take a single IP address.All IP addresses are specified in standard Internet "dot" notationand 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, causingbootpdto lookup the IP address for that host name using gethostbyname(3).If theiptag is not specified,bootpdwill determine the IP address using the entry name as the host name.(Dummy entries use an invalid host name to avoid automatic IP lookup.)

Thehttag specifies the hardware type code as either an unsigned decimal, octal, orhexadecimal integer or one of the following symbolic names:ethernetoretherfor 10Mb Ethernet,ethernet3orether3for 3Mb experimental Ethernet,ieee802,tr,ortoken-ringfor IEEE 802 networks,pronetfor Proteon ProNET Token Ring, orchaos,arcnet,orax.25for Chaos, ARCNET, and AX.25 Amateur Radio networks, respectively.Thehatag takes a hardware address which may be specified as a host nameor in numeric form. Note that the numeric formmustbe specified in hexadecimal; optional periods and/or a leading '0x' may beincluded for readability. Thehatag must be preceded by thehttag (either explicitly or implicitly; seetcbelow).If the hardware address is not specified and the type is specifiedas either "ethernet" or "ieee802", thenbootpdwill try to determine the hardware address using ether_hton(3).

The hostname, home directory, and bootfile are ASCII strings which may beoptionally surrounded by double quotes ("). The client's request and thevalues of thehdandbfsymbols determine how the server fills in the bootfile field of the bootpreply packet.

If the client provides a file name it is left as is.Otherwise, if thebfoption is specified its value is copied into the reply packet.If thehdoption is specified as well, its value is prepended to theboot file copied into the reply packet.The existence of the boot file is checked only if thebs=autooption is used (to determine the boot file size).A reply may be sent whether or not the boot file exists.

Some newer versions oftftpdprovide a security feature to change their root directory usingthechroot(2)system call.Thetdtag may be used to informbootpdof this special root directory used bytftpd.(One may alternatively use thebootpd"-c chdir" option.)Thehdtag is actually relative to the root directory specified by thetdtag.For example, if the real absolute path to your BOOTP client bootfile is/tftpboot/bootfiles/bootimage, andtftpduses /tftpboot as its "secure" directory, then specify the following inbootptab:

:td=/tftpboot:hd=/bootfiles:bf=bootimage:

If your bootfiles are located directly in /tftpboot, use:

:td=/tftpboot:hd=/:bf=bootimage:

Thesatag may be used to specify the IP address of the particular TFTP serveryou wish the client to use. In the absence of this tag,bootpdwill tell the client to perform TFTP to the same machinebootpdis running on.

The time offsettomay be either a signed decimal integer specifying the client'stime zone offset in seconds from UTC, or the keywordautowhich uses the server's time zone offset. Specifying thetosymbol as a boolean has the same effect as specifyingautoas its value.

The bootfile sizebsmay be either a decimal, octal, or hexadecimal integer specifying the size ofthe bootfile in 512-octet blocks, or the keywordautowhich causes the server to automatically calculate the bootfile size at eachrequest. As with the time offset, specifying thebssymbol as a boolean has the same effect as specifyingautoas its value.

The vendor magic cookie selector (thevmtag) may take one of the following keywords:auto(indicating that vendor information is determined by the client's request),rfc1048orrfc1084(which always forces an RFC1084-style reply), orcmu(which always forces a CMU-style reply).

Thehntag is strictly a boolean tag; it does not take the usual equals-sign andvalue. It's presence indicates that the hostname should be sent to RFC1084clients.Bootpdattempts to send the entire hostname as it is specified in the configurationfile; if this will not fit into the reply packet, the name is shortened tojust the host field (up to the first period, if present) and then tried.In no case is an arbitrarily-truncated hostname sent (if nothing reasonablewill fit, nothing is sent).

Often, many host entries share common values for certain tags (such as nameservers, etc.). Rather than repeatedly specifying these tags, a fullspecification can be listed for one host entry and shared by others via thetc(table continuation) mechanism.Often, the template entry is a dummy host which doesn't actually exist andnever sends bootp requests. This feature is similar to thetcfeature oftermcap(5)for similar terminals. Note thatbootpdallows thetctag symbol to appear anywhere in the host entry, unliketermcapwhich requires it to be the last tag. Information explicitly specified for ahost always overrides information implied by atctag symbol, regardless of its location within the entry. Thevalue of thetctag may be the hostname or IP address of any host entrypreviously listed in the configuration file.

Sometimes it is necessary to delete a specific tag after it has been inferredviatc.This can be done using the constructiontag@which removes the effect oftagas intermcap(5).For example, to completely undo an IEN-116 name server specification, use":ns@:" at an appropriate place in the configuration entry. After removalwith@,a tag is eligible to be set again through thetcmechanism.

Blank lines and lines beginning with "#" are ignored in the configurationfile. Host entries are separated from one another by newlines; a single hostentry 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. Tagsmay appear in any order, with the following exceptions: the hostname must bethe very first field in an entry, and the hardware type must precede thehardware address.

An example/etc/bootptabfile follows:

        # Sample bootptab file (domain=andrew.cmu.edu)        .default:\                :hd=/usr/boot:bf=null:\                :ds=netserver, lancaster:\                :ns=pcs2, pcs1:\                :ts=pcs2, pcs1:\                :sm=255.255.255.0:\                :gw=gw.cs.cmu.edu:\                :hn:to=-18000:        carnegie:ht=6:ha=7FF8100000AF:tc=.default:        baldwin:ht=1:ha=0800200159C3:tc=.default:        wylie:ht=1:ha=00DD00CADF00:tc=.default:        arnold:ht=1:ha=0800200102AD:tc=.default:        bairdford:ht=1:ha=08002B02A2F9:tc=.default:        bakerstown:ht=1:ha=08002B0287C8:tc=.default:        # 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:        gastonville:ht=6:ha=7FFF81000A47:tc=.default:        hahntown:ht=6:ha=7FFF81000434:tc=.default:        hickman:ht=6:ha=7FFF810001BA:tc=.default:        lowber:ht=1:ha=00DD00CAF000:tc=.default:        mtoliver:ht=1:ha=00DD00FE1600:tc=.default:

FILES

/etc/bootptab

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BOOTPTAB

NAME

DESCRIPTION

FILES

SEE ALSO

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