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BOOTPTAB(5)                   File Formats Manual                  BOOTPTAB(5)

       bootptab - Internet Bootstrap Protocol server database

       The bootptab file is the configuration database file for bootpd, the
       Internet Bootstrap Protocol server.  Its format is similar to that of
       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:


       where hostname is the actual name of a bootp client (or a "dummy
       entry"), and 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 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 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.  :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, where 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 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.

       The following tags take a whitespace-separated list of IP addresses:
       cs, ds, gw, im, lg, lp, ns, nt, ra, rl, and ts.  The ip, sa, sw, sm,
       and 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 bootpd to lookup the IP address for
       that host name using gethostbyname(3).  If the ip tag is not specified,
       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

       The ht tag specifies the hardware type code as either an unsigned
       decimal, octal, or hexadecimal integer or one of the following symbolic
       names: ethernet or ether for 10Mb Ethernet, ethernet3 or ether3 for 3Mb
       experimental Ethernet, ieee802, tr, or token-ring for IEEE 802
       networks, pronet for Proteon ProNET Token Ring, or chaos, arcnet, or
       ax.25 for Chaos, ARCNET, and AX.25 Amateur Radio networks,
       respectively.  The ha tag takes a hardware address which may be
       specified as a host name or in numeric form.  Note that the numeric
       form must be specified in hexadecimal; optional periods and/or a
       leading '0x' may be included for readability.  The ha tag must be
       preceded by the ht tag (either explicitly or implicitly; see tc below).
       If the hardware address is not specified and the type is specified as
       either "ethernet" or "ieee802", then bootpd will try to determine the
       hardware address using ether_hostton(3).

       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 hd and bf symbols determine how the server fills
       in the bootfile field of the bootp reply packet.

       If the bf option is specified, its value is copied into the reply
       packet.  Otherwise, the name supplied in the client request is used.
       If the 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 bootpd
       because the boot file may be on some other machine.

       The bs option specified the size of the boot file.  It can be written
       as bs=auto which causes bootpd to determine the boot file size

       Some newer versions of tftpd provide a security feature to change their
       root directory using the chroot(2) system call.  The td tag may be used
       to inform bootpd of this special root directory used by tftpd.  (One
       may alternatively use the bootpd "-c chdir" option.)  The hd tag is
       actually relative to the root directory specified by the td tag.  For
       example, if the real absolute path to your BOOTP client bootfile is
       /tftpboot/bootfiles/bootimage, and tftpd uses /tftpboot as its "secure"
       directory, then specify the following in bootptab:


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


       The 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, bootpd
       will tell the client to perform TFTP to the same machine bootpd is
       running on.

       The time offset to may be either a signed decimal integer specifying
       the client's time zone offset in seconds from UTC, or the keyword auto
       which uses the server's time zone offset.  Specifying the to symbol as
       a boolean has the same effect as specifying auto as its value.

       The bootfile size bs may be either a decimal, octal, or hexadecimal
       integer specifying the size of the bootfile in 512-octet blocks, or the
       keyword auto which causes the server to automatically calculate the
       bootfile size at each request.  As with the time offset, specifying the
       bs symbol as a boolean has the same effect as specifying auto as its

       The vendor magic cookie selector (the vm tag) may take one of the
       following keywords: auto (indicating that vendor information is
       determined by the client's request), rfc1048 or rfc1084 (which always
       forces an RFC1084-style reply), or cmu (which always forces a CMU-style

       The 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.  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).

       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 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 tc feature of
       capfile(5).  Note that bootpd allows the tc tag symbol to appear
       anywhere in the host entry, unlike capfile which requires it to be the
       last tag.  Information explicitly specified for a host always overrides
       information implied by a tc tag symbol, regardless of its location
       within the entry.  The value of the tc tag may be the hostname or IP
       address of any host entry previously listed in the configuration file.

       Sometimes it is necessary to delete a specific tag after it has been
       inferred via tc.  This can be done using the construction tag@ which
       removes the effect of tag as in 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 @, a
       tag is eligible to be set again through the tc mechanism.

       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.

       An example /etc/bootptab file follows:

            # Sample bootptab file (domain=andrew.cmu.edu)

                 :ds=netserver, lancaster:\
                 :ns=pcs2, pcs1:\
                 :ts=pcs2, pcs1:\


            # Special domain name server and option tags for next host
                 :T99="Special ASCII string":\



       bootpd(8), tftpd(8),
       DARPA Internet Request For Comments RFC951, RFC1048, RFC1084, Assigned

4.3 Berkeley Distribution      October 31, 1991                    BOOTPTAB(5)