COMMENT ⊗   VALID 00006 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002				     Host Table Information
C00004 00003				    Tables and Table Formats
C00007 00004					Update Procedure
C00012 00005				       Files on [HST,NET]
C00014 00006				       Other useful files
C00015 ENDMK
C⊗;
			     Host Table Information

Host tables are used to translate between host names (text strings supplied by
the users of network programs) and host numbers required by the operating
system.  The directory [HST,NET] contains most of the files pertaining to host
tables.

As of June 1983, we use an internal form of host tables known as HOSTS3.  This
is a PDP-10-based representation designed especially for Internet host names and
numbers, corresponding to the format outlined in RFC 810.  HOSTS3 format also
handles PUP host numbers on Stanford's local Ethernet.

Host tables change from time to time, and they must be kept up-to-date.  At
SAIL, this is done by checking for a new version of the Network Information
Center (NIC) host table once a day, and retrieving it if it has changed; also
checking for a new version of the PUP network directory.  The PUP network
directory is converted from its binary form to a text file in RFC810 form.  It
and the NIC table are then merged into the HOSTS3-format binary table.
			    Tables and Table Formats

The specification of the text form of host tables can be found in RFC 810,
available as the file <NETINFO>RFC810.TXT at SRI-NIC.  (If a local copy is kept,
it should be stored as RFC810.TXT[RFC,NET].)  It is not too important that this
syntax be understood, because the HOSTS3 program takes care of the details.  The
latest copy of the NIC host table is stored as <NETINFO>HOSTS.TXT at SRI-NIC,
but it is retrieved using the Hostname Server rather than with FTP.  It is
stored as HOSTS.TXT[HST,NET] at SAIL.

A description of the binary format of the PUP Network Directory can be found in
the file <Pup>PupDirectory.press on the IFS.  The directory is stored in binary
form on several hosts; the master copy should be at Navajo in the file
/usr/local/Pup-Network.Directory.  It is retrieved using the PUP Network
Directory Update protocol, and stored as PUPNET.DIR[HST,NET] at SAIL.

Sometimes we retrieve the text source used to generate this directory, although
it is not read by any programs on SAIL.  It is stored as PUPNET.TXT[HST,NET].

The file PUPHST.TXT[HST,NET] contains a locally-generated text form of the PUP
Network Directory, in RFC810 format to allow merging with HOSTS.TXT[HST,NET].
An Ethernet host number such as 50#302 is shown in the file as SU 50#302.

Finally, HOSTS3.BIN[HST,NET] is the binary host table read by most network
programs.  Its format is described in comments in the files HOSTS3.MID[HST,NET],
NETWRK.MID[S,NET] and NETWRK.FAI[S,NET].

There is also a text file, TTYLOC.TXT[HST,NET], giving TTY locations for
Ethertip ports and other local Ethernet hosts.  This is maintained at Score.
There is no binary form; programs that read the file (currently only CHTSER,
using the TTYSTR routine in the NETWRK package) interpret the text.
				Update Procedure

At present, the update procedure is semi-automatic.  It will eventually require
no intervention unless unexpected errors are encountered.

At 3:00 a.m. each day, [HST,NET] runs a batch job (BAT0), which runs the
program UPDATE[HST,NET].  Currently this program does the following things.

1. Queries the NIC Hostname Server to find out the version of its HOSTS.TXT.
   (This is returned as a string.  If you want to do it manually, the
   easiest way is to Telnet to port 101 (decimal) at SRI-NIC, and type the
   command "VERSION".)

2. Reads the version string corresponding to SAIL's current HOSTS.TXT.	This
   string is stored in HOSTS.VER[HST,NET].

3. If they are different, retrieves a new HOSTS.TXT from the Hostname Server
   (using the "ALL" command).

4. Reads the version of our current PUP Network Directory, which is stored
   in the header part of the file (PUPNET.DIR[HST,NET]).

5. Broadcasts this version number in a PUP packet, which will elicit responses
   from any hosts who have a higher version number.

6. Requests a new directory from any host that claims to have a higher number.
   This is stored in PUPNET.DIR[HST,NET], and also converted to text form and
   stored as PUPHST.TXT[HST,NET].

If either the NIC host table or the PUP Network Directory was updated, UPDATE
then sends a message to BUG-HOST (currently, this forwards to JJW).

By examining BAT0.LOG, you can see which of the tables was updated.  If the
change is trivial, you may not want to bother making a new HOSTS3.BIN.  But to
see the changes, you have to compare the new files with saved versions of the
old files.  Eventually UPDATE will do this.

At present, we remove the entry for MIT-AI-RESERVED from HOSTS.TXT (by editing
the file and inserting a ";" at the beginning of its line).  The NIC has been
asked to remove this, but so far they haven't done so.

To merge HOSTS.TXT and PUPHST.TXT and write a new host table, type

	.al hst,net
	.do merge

This will install a new HOSTS3.BIN, if all goes well.  (There will probably be
some non-fatal "Gateway/Host duplicate addr" messages from the HOSTS3 program.)

The TTY location file is not automatically updated.  To get a new version of it,
give the command

	.ftp ttyloc.txt[hst,net]←{score/<account>}finger:ttyloc.cmd

where <account> is your Score account name.  It may be useful to SRCCOM the old
and new versions to detect changes.

To update the text version of the PUP Network Directory (which is kept here as
PUPNET.TXT[HST,NET] for unofficial purposes only), retrieve it (in Ascii mode)
from one of the following places:
;
; Stored on:	[Navajo]/usr/local/Pup-Network.tx	/* MASTER COPY */
;		[Lassen]<System>Pup-Network.txt
;		[SCORE]SYSTEM:PUP-NETWORK.TXT
;		[Shasta]/usr/local/Pup-Network.tx
;		[Diablo]/usr/local/Pup-Network.tx
;		[Whitney]/usr/local/Pup-Network.tx
;		[SUMEX]SYSTEM:PUP-NETWORK.TXT
;		[SUMEX-2020]SYSTEM:PUP-NETWORK.TXT
			       Files on [HST,NET]

BAT0.DMP	The nightly batch job
BAT0.LOG	Batch job output log
DO.DO		Various DO command segments
HOSTS.TXT	Latest version of the NIC host table
HOSTS.VER	Version string corresponding to HOSTS.TXT
HOSTS3.BIN	HOSTS3-format binary host table
HOSTS3.DMP	Program to produce HOSTS3.BIN
HOSTS3.MID	Source for HOSTS3.DMP
MERGE.TXT	Input for HOSTS3 program to merge NIC and PUP tables
PUPHST.TXT	RFC810 form of PUP Network Directory
PUPNET.DIR	Latest version of PUP Network Directory
PUPNET.TXT	Text source of PUP Network Directory
TTYLOC.TXT	TTY locations, for FINGER
UPDATE.CTL	Commands for nightly batch job
UPDATE.DMP	Program to retrieve host tables
UPDATE.FAI	Source for UPDATE.DMP
			       Other useful files

NETWRK.FAI[S,NET]	FAIL version of the NETWRK I/O package
NETWRK.MID[S,NET]	MIDAS version of the NETWRK I/O package

Most of the programs on [S,NET] read the host table.  Other programs that do are

MAIL.FAI[MAI,SYS]
NXP[SPL,SYS]		(to find Boise)
PRESS.FAI[CSP,SYS]	(to find the Dover)
PUPTIM.FAI[CSP,SYS]
WHERE.FAI[CSP,SYS]
WHO[CSP,SYS]

(Please add to the above list any missing programs.)