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       bootptab - Internet Bootstrap Protocol server database


       The  bootptab  file  is the configuration database file for bootpd, the
       Internet Bootstrap Protocol server.  It’s format is similar to that  of
       termcap(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:

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

       where  hostname  is  the  actual  name  of  a bootp client (or a "dummy
       entry"), and tg is a two-character tag symbol.  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 equals-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
            dl   DHCP lease time in seconds
            dn   Domain name
            ds   Domain name server address list
            ef   Extension file
            ex   York ex option (huh?)
            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
            ms   Message size
            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_hton(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 client provides a file name it is left as is.  Otherwise, if the
       bf option is specified its value is copied into the reply  packet.   If
       the  hd option is specified as well, its value is prepended to the boot
       file copied into the reply packet.  The existence of the boot  file  is
       checked  only if the bs=auto option is used (to determine the boot file
       size).  A reply may be sent whether or not the boot file exists.

       Some newer versions of tftpd(8) 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  (including  domain)  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
       termcap(5)  for  similar terminals.  Note that bootpd allows the tc tag
       symbol to appear anywhere in  the  host  entry,  unlike  termcap  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 termcap(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 (

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


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



              The definition file


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