tcp-group FAQ	draft					15-Nov-92

[This is a draft -- forgive ugliness, and help repair it!]

This is the FAQ for tcp-group@ucsd.edu.  It discusses the TCP/IP
implementation known as NOS, originated by Phil Karn and developed by
many others.

This FAQ tries not to duplicate material that is available elsewhere,
but refers instead to existing documentation.  If you have never
seen NOS before, you might want to scan this document quickly,
and then go read the "Introduction to NOS" file by John Ackermann
or the "Beginner's Guide to TCP/IP" (both described later).

If you maintain or use a NOS variant, please check its description
here in this FAQ.  If it's wrong, or if there isn't one, please tell
the FAQ maintainer.  Other additions and corrections are also welcome.

This FAQ is maintained by mg@bds.com, as of November 1992.

----------------------------------------------------------------------
Repositories

    The best place to get NOS is from someone you know who is already
    using it.

    You can get it over the Internet from several anonymous FTP sites.
    The best-known site is ucsd.edu.

	ucsd.edu:/hamradio/packet/tcpip

        grivel.une.edu.au	(Australian mirror of ucsd.edu)

	[ ucsd needs a README with one-liners for each directory ]

    It is also found on many telephone BBS systems, including:

	N8EMR's Ham BBS	(614) 895-2553
	ChowdaNet	(401) 331-0334
	WB3FFV		(301) ?
	Gracilis BBS	?
        AMNET BBS       +61-3-366-7055 (Australia)

    N1BEE distributes a cleaned-up version of the GRI code.  The
    primary distribution point is ChowdaNet.  This seems to be
    one of the more stable and solid end-user releases, though the
    last version is nearly a year old now.


Documentation

    Unfortanately, NOS is poorly documented compared to many other
    programs.  This is not due to a lack of effort by the developers.
    It is because there are so many versions of NOS, being
    developed by many people who have no regular contact, and each
    version changes very frequently.  Any documentation quickly
    becomes out of date.

    For some features, there is no documentation at all.  Other
    features that are documented aren't present in all executables,
    even those produced by the same source, because that feature may
    have been turned off in the executable you are using.

    Thus, it is likely that the documentation you can find won't
    exactly match the program you are using, and you will have to
    refer to a full "base" manual and to another document that
    describes the differences from the base version.


    intronos.zip  This is the best introduction to NOS for people
		  who understand something about packet radio.
		  
    userman.zip	  A complete user manual for the last pre-NOS version
		  of NET... 890421.1

    nos_1229.man  A complete user manual for PA0GRI NOS.

    help_v02.zip  mailbox help files (for ka9q 901130)

    The several volumes of the ARRL Computer Networking Conference (CNC)
    Proceedings contain many papers on TCP/IP and NOS.  These are
    available from ARRL Headquarters in Newington, CT.

    Send mail to info@arrl.org for an automatic response pointing at
    more information about the ARRL.

    Particularly useful CNC articles are listed in the bibliography
    at the end of this document.

    Some of these papers are available online in the directory
    ucsd.edu:/hamradio/packet/tcpip/docs.

    Other papers are also available on ucsd.edu:

	ka9qnos.ps.Z
	netnix-paper.ps.Z
	connex.Z
	1987			Directory of papers from CNC 1987
	1988			Ditto 1988

    There is no document dedicated to describing the internals of NOS.
    There is a section of the user manual that describes some of the
    socket library calls.  Look in the section on NOS Internals here
    in this FAQ.

    I hesitate to make the offer, but on a time-permits basis I can provide
    a hard-copy set of my doc, the PA0GRI ref manual, the Rutgers tcp/ip
    intro, and a disk with N1BEE's GRINOS for the cost of copying and
    mailing -- usually $10 or $15.  It's best to call, write, or email first
    to find out what the turnaround time is likely to be.  My mailing
    address:

    John Ackermann   AG9V
    2371 Stewart Road
    Xenia, OH   45385
 

    Gary Ford <ford@eecs.ucdavis.edu> has written a "Beginner's Guide
    to TCP/IP on the Amateur Packet Radio Network Using the KA9Q
    Internet Software" alternately titled "End User's Guide to TCP/IP".
    Version 2.0 of the guide documents the use of NOS 911229 (PA0GRI
    v2.0h) and BM v3.3.2.  It is available on:

	ftp.eecs.ucdavis.edu:pub/ka9q
     or ucsd.edu:hamradio/packet/tcpip/docs

    nosbgnlp.zip    unzips to a 66 page ascii "line printer" document,
		    which can be printed with the UNIX lpr command.

    nosbgnps.zip    unzips to a 54 page PostScript document, which can
		    be printed on a PostScript printer.

    nosbgnpr.zip    unzips to a 66 page ascii "print" document, which
		    can be printed using the DOS print command.  You
		    will need to send control codes to your printer to
		    control the page offset and you should turn
		    perforation skip off.  (not on ucsd.edu)


Mailing lists

    tcp-group@ucsd.edu

	This is a forum for NOS developers to discuss things they're doing.

	Send mail to listserv@ucsd.edu with the word HELP as its only contents.
	It will send you instructions by return mail.

    nos-bbs@hydra.carleton.ca

	The purpose of this list is discussion of the ins and outs of running
	KA9Q NOS as something approximating a full-service BBS, which generally
	boils down to discussion of the care and feeding of the JNOS version of
	NOS, maintained by Johan, WG7J.  Discussion of peripheral issues which are
	likely to be of interest to NOS BBS sysops, such as the convers server,
	NNTP, POP, etc, are also welcome.

	Submissions to the list go to:
	nos-bbs@hydra.carleton.ca

	Subscription/deletion requests and other administrivia to:
	nos-bbs-request@hydra.carleton.ca

	Note that the reply path for list mail is set to go to the list address,
	not the originator.  That's by design - to encourage *public* discussion.
	If you want to send private mail to a nos-bbs contributor, please take
	care to get the address right!


Operating systems and other machines

    NOS has been ported to several operating systems.
    Most development still happens under DOS.
    At some point, there may have been a time when all the different
    platforms could have been built from a single set of sources.
    Since then, they have diverged enough that re-integrating the
    changes back into a common set of sources would take some effort.

    <bdale@col.hp.com>

    When the list of targets was really small, in about 1988-9 maybe, we had a
    single set of sources that built on various targets... the 890421.1 release
    supported DOS/Borland and a variety of Unix variants.  I haven't paid much
    attention to this since then.


    OS/2
    Windows
    Macintosh
    Amiga


Installation and setup tools

    An installation program for some versions of NOS is available.


    The NOS_KIT package explains well the several files used by NOS for
    configuration.
    It is a package for installation of the 901130 versions of KA9Q
    and G1EMM NOS (it includes executables for 901130 G1EMM and KA9Q).
    This "kit" is a reasonable place for a newcomer to get started.

    Written:  Dave Fritsche (wb8zxu)
    E-mail:   dlf@phx.mcd.mot.com
    Version:  910324
    Path:     UCSD.EDU /hamradio/packet/tcpip/install/nos_kit.*


    The "kit" should be unpacked and placed onto floppy disks.  It all fits on
    a single 720k or larger disk.  This disk is then used as a NOS installation
    disk (the files can also just be stuffed into a subdirectory on a harddisk
    if you prefer -- but put them in a directory close to root (c:\) -- long
    pathnames screw things up).  Once the installation disk is ready (I hand
    them out to locals), just put the disk in a drive, change to the drive
    (e.g:  a:), then type "install".  The user is presented with two screens
    of "fill in the blanks" kind of data.  Just use the <Enter>, <Tab>,
    <SHFT><Tab>, <Up-arrow>, and <Down-arrow> to move between the entries.
    It's pretty self-explanatory.  There are a couple of questions that weren't
    very clear, that should be cleaned up.  But it's something to help get
    a person off on the right foot.  After the blanks have been filled in,
    the installer goes off and makes all the needed subdirectories, creates
    an autoexec, ftpusers, domain.txt, . . ., and then unpacks the binaries
    and all the support files.

    The "kit_src.*" files, are the source code for the "install" program
    contained in the kit.  Numerous people have recently asked me for the
    source code, so that they could update the installation kit for GRI/WG7J
    NOS.  Sure hope they can pull it off!  Wish I had the time to do it
    myself.  Hopefully, Brian will get this source code moved into the "install"
    directory at some time in the near future.  Generally speaking, endusers
    won't need or want these source archives.


Versions

    The main NOS repository harbors a bewildering variety of NOS variants.
    All of them are derived in some way from some ancestor of the
    KA9Q version.  The one that is best for you depends on what you
    want to use it for.

    One reason why there are so many versions of NOS is that it is
    used for widely different purposes by different groups.
    Each one needs it to solve a particular problem, or provide some
    service, so they implement whatever feature they need.  There are
    many such groups throughout the world, and many of them have no
    regular contact with any of the others.

    Each NOS variant tends to reflect the cumulative efforts of a
    person or group, rather than a particular added feature.  Some
    people modify more than one area -- for instance, they might add a
    new TCP server, and "enhance" the way datagrams are routed.

    The variants are usually known by the names of their authors,
    and they often have nicknames.  Some of the more common ones are

	ka9q
	wg7j (jnos)
	pa0gri
	grinos		based on PA0GRI, cleaned up by N1BEE
	gracilis
	wnos	       
	hrlnos
	gpsnos		Georgia Packet Switch, produced by GRAPES
			(Georgia Radio Amateur Packet Enthusiasts)
	wampes
	g1emm
	pmnos


    Most versions of NOS share a common core of commands.

    Most versions of NOS have all of the following facilities in them,
    but emphasize one over the others:

        packet switch
        services
        UI terminal

    For example, GPSNOS is optimized to be a standalone packet switch,
    and doesn't offer any other services.  (This is what DOS NOS is
    really best at.) WNOS has a nice split-screen user interface, and
    PMNOS has an even more elaborate one.


    The features supported by NOS can be divided into categories this way:

	 network		NETROM, FlexNet
	 user-interface		split-window, fkey
	 hardware		special serial ports, network interfaces
	 services		callbook server, pop, smtp, convers, mailbox

    Here is a list of the features by category:

	Network

	    TCPIP
	    AX.25
	    NETROM
	    WAMPES AX.25 routing	WNOS, WAMPES

	hardware

	    asy	standard PC serial port
	    hs	high-speed serial driver for 8530 (no DMA)
	    scc	generic 8530 driver
	    DRSI
	    EAGLE
	    PI
	    PACKTWIN
	    dialer

	services

	    ttylink (chat)
	    mbox
	    bbs
	    convers
	    pop
	    smtp
	    nntp
	    ftp
	    finger
	    callbook	gracilis

	user-interface

	    split-screen (WNOS)
	    scrolling, cut/paste, mouse (PMNOS)
	    fkey


    ----------------------------------------------------------------------


	These versions have been optimized as packet switches:

	      ka9q
	      gpsnos
	      pe1chl nos
	      pa0gri
	      gracilis

	These versions emphasize user-interface:

	      hrlnos
	      minihrl
	      wnos
	      pmnos

	These versions emphasize services:

	      wg7j

    ----------------------------------------------------------------------

    Here are brief descriptions of some NOS variants.  If your
    favorite one isn't here, or if you can describe it better, tell me!
    I'm particularly interested in documenting ancestry where possible.


    net	    Phil Karn <karn@qualcomm.com>

	    The last pre-NOS version of NET... 890421.1
	    documentation in userman.zip


    ka9q						  	    21-Jun-92
	    Phil Karn <karn@qualcomm.com>

	    This is the base version from which the others are derived.

	    [ I haven't tried this one yet. - mg ]

	    Latest version on ucsd is 920621.

	    wb8zxu:
	    A lot of people consider 901130 the last "really good" working version of
	    NOS.  After that version, NOS got real fat, and fairly quirky.  It also
	    split about 5 different ways . . . PA0GRI, WG7J, PMNOS, WNOS, . . .

    wg7j		  					    15-Sep-92
	    Also called JNOS.

	    This is one of the more actively developing versions.

	    Based on KA9Q 911229 release, at least up to JNOS 1.05.
	    Later versions will be based on KA9Q 920618.

	    This is a service-oriented NOS.  It acts as a "full-service" bbs.
	    It can exchange mail with conventional amateur BBS systems,
	    such as MSYS and W0RLI, as well as via SMTP and NNTP.

	    This version is also widely used as a gateway between
	    internet and amateur packet radio networks.

	    This has a rewritten 8250 UART driver.
	    [I've found it to be slower than the previous one -- see
	     later -mg]

	    Derived somehow from was0206, pa0gri, wnos.


    pa0gri		      					    29-Dec-91
	    Gerard van der Grinten, PA0GRI
		
	    This is one of the more actively developing versions.
	    This is used as the basis for other versions, including gracilis.

	    nos_1229
	    gri20m

	    mods allowing accessing many disk drives by FTP server
	    made for GRINOS 1.8b, draft version for 2.0l and (in
	    nearest future) 2.0m available by anonymous FTP on
	    zfja-gate.fuw.edu.pl (name GRI20L-1.ZIP).  Jerzy Tarasiuk
	    <jt@zfja-gate.fuw.edu.pl>

	    N1BEE does distribute a cleaned-up version of the GRI code.

    grinos
	    Mike Bilow N1BEE	<MIKEBW@ids.net>

	    The primary distribution point is ChowdaNet.

	    (GRINOS is not a synonym for PA0GRI NOS.)

	    This is a cleaned-up and packaged version based on the pa0gri.
	    It is one of the more stable and solid end-user
	    releases.

	    Mike tries to make sure that his bug fixes are recycled
	    into the main PA0GRI releases, so you only tend to run a
	    version or two ahead on bug fixes with GRINOS.


    gracilis
		info@gracilis.com
		Don Lemley N4PCR
		Milt Heath

        There seem to be several "gracilis" versions.  One is
        publically available on ucsd.edu.  It seems to be
	derived from pa0gri.

	Gracilis has a special version of NOS that runs in their
	PackeTen -- it doesn't run on a PC.
	The Gracilis PackeTen is a standalone packet switch with a
	special communications processor (the Motorola 68302).
	This standalone version is derived from work described in a
	paper on NOSINABOX by Bdale Garbee, Don Lemley, and Milt Heath
	in the CNC proceedings.

	There are rumors that Gracilis has also substantially
	reworked NOS.  This version doesn't seem to be publically
	available in source form, but they supply it with 
	their PackeTwin (and PackeTen) modem/radio hardware.

	[Are the binaries available, and will they support other
	 hardware devices?]

	Says bdale:
	    NOS is integral, and doesn't look a whole lot like NOS internally any more.
	    Don Lemley and Milt Heath at Gracilis acquired a commercial text-based window
	    system with source, and heavily modified it to work in a mutli-task
	    environment.  They also found and have integrated an overlay manager to deal
	    with the memory size problems.  Don has spent considerable time finding and
	    squashing memory leaks, and other problems in NOS.  What they ended up with
	    is a completely different user interface to a package that does all of what
	    NOS does, and more.

    wnos			     			    14-Jan-92
	    Michael Bentrup (DB3FL)
	    Mike Chace (G6DHU @ GB7IMB)

	    ucsd.edu:/hamradio/packet/tcpip/wnos

	    A very detailed set of manuals for WNOS3 and 4 is in the
	    wnos directory on ucsd.edu.

	    The author of this software Michael Bentrup (DB3FL).  He
	    is sadly not connected to the Internet.  Mike Chace (G6DHU
	    @ GB7IMB) produces a version of the software more suited
	    to the UK environment where, for example, NET/ROM is
	    required.

	    WNOS was the first system to port two important features of the
	    WAMPES Unix software namely the AX.25 autorouting front-end and
	    the convers server. As far as I know, ALL flavours of NOS that
	    support the convers server have used the WNOS code and therefore
	    should be compatible.

	    A unique feature of WNOS is the AX.25 autorouter.

	    The WNOS front end allows a system to network at Level 2. The WAMPES
	    AX.25 front-end stores paths to other AX.25 systems and users may use
	    these paths without reference to the full path. Each system along the
	    path simply looks up the next hop, opens a connection at L2 and relays
	    the frames. All this is transparent to any user, be they an ordinary
	    L2 user or someone using L2 to push TCP/IP through a network. Example

		    G6DHU   ->  G4WRW   ->   G7XXX  -> G8YYY

	    If G4WRW has a route to G8YYY (via G7XXX), G6DHU can use this route
	    without reference to the full path. In other words, all G6DHU need
	    do to open a connection to G8YYY is say

		    connect G8YYY via G4WRW

	    as soon as G4WRW sees the connect request, he will open a connection
	    to G7YYY via G7XXX. Therefore, each link on the path is hop-to-hop
	    acknowledged and the end users only need to know their nearest link
	    in the path and the final destination in order to be routed through
	    the system. Also, any traffic directed through your system in this
	    way, will have the path information saved and therefore available
	    for future use.

	    WNOS is also unique in that it remembers (and saves to disk) ALL of
	    the routing table information

		    AX.25 paths (as discussed above)
		    NET/ROM routing table
		    ARP table
		    IP routing table

	    Therefore, with WNOS it is quite feasible to start with a system
	    completely devoid of routing table information and then get to
	    know all this information dynamically. Also, as paths etc change,
	    tables are automatically saved and updated on disk. It is a neat
	    system!

	    WNOS was also the first version of NOS to support real time data
	    compression using LZW coding. email (via SMTP), news articles
	    (via NNTP) and convers interlink traffic may all be transferred
	    in data compression mode. Data is compressed before sending and
	    results in an average of 45-55% reduction in data transferred
	    against plain-text transfer.

	    Another item of interest is the NNTP system. WNOS contains everything
	    that allows a user to deal with news articles. There is a news poster
	    and a news reader. The NNTP filesystem is automatically updated, for
	    example, if an article arrives for a newsgroup unknown to the local
	    system. The news spool is updated immediately and the articles accepted.
	    WNOS also contains a special server which allows AX.25 mail to be
	    converted to an NNTP news article and cross-posted to a newsgroup.


	    This is most suited as an end-user node, rather than as a network
	    service provider -- that is, it's a better terminal than bbs.

	    Has a split-window user interface.
	    A status line at the top of the screen displays info
	    about the current window, and indicates when there is new
	    activity on other windows.
	    (Each "window" is really a full screen.  You can switch among
	    screens, but they don't overlap.)
	    There is an input area at the bottom of the screen.
	    attribute command sets monitor type <color|mono>.

	    Supports convers, though probably not compatible with JNOS.

	    The 'w' in the name is for WAMPES, which is an AX.25 routing
	    mechanism (used in FlexNet?).

	    By the way, I had a quick look in WNOS docs and it seems WNOS
	    is ONLY a packet switch, it supports neither SMTP nor BBS message
	    commsnds.

    hrlnos							19-Mar-92
	    by R. Kolb PA3EUG pa3eug@pi8hrl.ampr.org; PA3EUG @ ON4UBO;
	    Derived from PA0GRI 16-Aug-91.

	    Has a split-window user interface like WNOS.

	    FlexNet: hop-to-hop-ack digipeating

	    mbox log
	    mem efficient
	    mem thresh

	    mode ipcam	uses AX25 PID Text rather than IP.

	    Does AX.25 autorouting.

	    timers reworked.  IP times are now dynamic.
	    Saves arp cache to disk.

	    minihrl is a smaller version of hrlnos.
	    It has no netrom support, thereby gaining 80k of memory.

    gpsnos			     				11-Nov-91
	    Based on KA9Q NOS 910420.
	    Optimized as a packet switch by GRAPES, B. Nebergall, K4TQL.
	    Adds netrom/ax25 switch optimizations, removes mailbox functions.
	    Has a remote sysop facility with a good "public" password protection scheme.
	    Supports up to 5 hardware ports, including 56K ports.

    pmnos
    	    Presentation manager NOS,
	    Walt Corey KZ1F  <kz1f@kz1f.ampr.org> <kz1f@giskard.uthscsa.edu>
	    Jack Spitznagel also fields questions about it.

	    There is no official "authoritative" drop site for PMNOS.

	    giskard.uthscsa.edu has been made available for
				Walt until he gets settled into a more favorable
				situation... so it tends to be the first place a
				revised beta appears...

	    The current beta version of PMNOS is PMNOS 1c. The
	    current PMNOS1C.ZIP file creation date -- time is: 9/24/92
	    -- 03:15:00 gmt

	    THIS IS STILL BETA! Please don't distribute this code
	    without making sure that it is accompanied by:

		    PMAIL.ZIP    9/18/92 -- 14:40:04
		    pmreadme.1st 10/6/92 -- (update includes this
					    message)

	    Users should have access to nos_1229.man(lp) (GRINOS manual)
	    and the readme files from JNOS 1.04... There is NO OTHER
	    documentation YET....



	    The "cleaned&cleared" release will be posted on UCSD.EDU and
	    the source code will be integrated with JNOS at version
	    1.05....

	    After Johan releases JNOS 1.05 (soon hopefully) a "current
	    working" compile of PMNOS will appear at UCSD.EDU and
	    at WG7J.AMPR.ORG.... The OS/2 and PM sources will be
	    combined with the rest of JNOS and an OS/2 compile selected
	    by #ifdef statements... IF everything goes well in the
	    project.  Currently, The IBM C set/2 compiler is the only
	    compiler that has been used to build PMNOS. I have
	    experimented with the GNU C/C++ compiler, but have had no
	    luck so far (I am not a "real programmer"). Other compilers
	    such as the forthcoming Borland, Zortech, and Watcom
	    compilers for OS/2 should work in competent hands.... But
	    these are still unknowns.

	    WARNING-- if you have not programmed the PM environment,
	    you had better go "larval stage" with the OS/2 'redbooks'
	    (and other PMwindow specific DOCS!!) for a while before
	    getting creative.... Stick to customized builds of the code
	    for YOUR OWN PURPOSES. PLEASE dont distribute new compiles
	    of this stuff!!! This ain't just DOS anymore!! The
	    'redbooks' can be downloaded from software.watson.ibm.com by
	    anonymous FTP.


	    Network driver support should be along later in the
	    year: Planned are SCC, PI, and an NDIS 'shim'.

	    The SCC and PI drivers will be loaded at IPL (in the
	    config.sys schema) as:

	    device=C:\OS2\SCC.SYS <parms similar to attach statement #1
				   in autoexec.nos>

	    The NDIS 'shim' will enable use of NDIS drivers in a manner
	    similar to the NDIS_PKT packet driver set. You will have to
	    scrounge up your own copy of the appropriate OS/2 NDIS driver,
	    protman.sys, etc.....

	    All of the above is subject to negation, reversal,
	    alteration, etc., by Walt Corey.


    wampes							16-Sep-92
    	    Dieter DK5SG / N0PRA <deyke@fc.hp.com>
	    ucsd.edu:/hamradio/packet/tcpip/wampes

	    WAMPES is a Unix based system derived from KA9Q. It supports all
	    the usual TCP, UDP and IP services and was the first to provide
	    the convers system (like the Internet's IRC). It was written by
	    Dieter Deyke (DK5SG) and ran exclusively on machines running the
	    HP-UX Unix flavour. It has since been ported to ISC and SCO Unix
	    running on PCs and within the last few monts it has been sucessfully
	    ported to Linux, the free Unix for 3/486 PCs.

	    It currently  supports HP 9000 series 300, 400,
	    700,  and 800  computers,  running  HP-UX  08.xx.  
	    It at least compiles on SunOS, but hasn't been thoroughly tested.

	    Alan Cox <iiitac@pyramid.swansea.ac.uk>

	    On the subject of wampes there is also a version for interactive unix
	    and allegedly one for linux (tho I've not traced this).


	    [How is this related from HRLNOS? ]

	    Regarding Unix releases of NET/NOS, K5JB has produced a
	    version for SCO Unix.  It does not seem to be available
	    anywhere for FTP.

    pe1chl							1-Jul-92

	    Network
		netrom fixes

		"ftl0" and "broadcast" protocols/command sets for access
		to the microsats like AO-16 and UO-22

	    UI changes
		fkey
		version
		screen

	    services
		bbs forwarding scripts

	    Costas SV1XV (ex G7AHN) <kkrallis@nrcps.ariadne-t.gr>

	    Regarding MINIHRL, the author PA3EUG states it is HRLNOS without
	    the NETROM code. I have been unable too to find the full HRL NOS
	    code, it is not on UCSD.EDU or on any other well known site.

	    PE1CHL is a release of NET.EXE with very limited  user services
	    very simple mailbox but it is reasonably well designed for ax25
	    and also supports the "ftl0" and "broadcast" protocols/command sets
	    for access to the microsats like AO-16 and UO-22.

	    We might run it here in Athnes on SV1IW's station to
	    create a TCP/IP sat gateway.

	    Good docs on PE1CHL are files NETDOC1.ARC and NETDOC2.ARC
	    in directroy /hamradio/packet/tcpip/pe1chl on ucsd.edu

	    G0BSX mail server:
	    ucsd.edu:/hamradio/packet/tcpip/g0bsx/server.tar.Z

    g1emm
    	    Kelvin Hill G1EMM	<kelvin@cix.compulink.co.uk>
	    ucsd.edu:/hamradio/packet/tcpip/g1emm

	    This was once a very actively developed version, but doesn't
	    seem to have grown much in the past year or two.
	    It branched off into PA0GRI (and hence GRINOS).

	    SV1XV:    Costas <kkrallis@leon.nrcps.ariadne-t.gr>

	    Kelvin also distributes SMALLEMM.EXE (without AX.25/NETROM/KISS, which
	    only supports SLIP and Ethernet interfaces) and is very small. I use
	    it on my laptop Amstrad PPC-640D. He also distributes an example
	    of a full G1EMM NOS installation in the file G1EMMKIT.ZIP.

	    N8GNJ:	    Steve Stroh     strohs@strohpub.com

	    I think that when Kelvin got out of NOS codesmithing (I
	    believe he had a child), PA0GRI took his code and started the now
	    popular PA0GRI variant of NOS.  The G1EMM code is
	    effectively obsolete, but it is probably maintained on
	    several systems.


    unknown

        Alan Cox <iiitac@pyramid.swansea.ac.uk>

	    There will be a ka9q net with smtp links to the O/S, host mode
	    login via ax25 and the ability to act like a netrom node for Linux
	    very soon. I'm just finishing debugging it. If I get it finished I'll
	    mail you if you want to stick it on the list.

----------------------------------------------------------------------
NOS Internals

    There is not a whole lot of documentation on NOS internals.

    The socket interface used by the TCP clients and servers closely
    resembles the one found in BSD Unix.

    The tricky parts arise in dealing with the multi-tasking kernel.

    More details on the NOS internals may be found in the following files:

	 [What internals documentation is there?]

Source code organization

    The sources are distributed in a single flat directory.
    The names of the files do not have prefixes that would identify
    the part of NOS to which they belong.

    The modules are divided into groups.  Each group of modules is
    placed in a library.

    Most variants of NOS are distributed in two or more packages.
    There are no guidelines for what to put in a distribution, or how
    to package them, so each NOS variant is distributed differently.

    NOS is generally packaged appropriately for the system that runs it.
    DOS versions of NOS are almost always packaged in zip files.
    Unix versions appear as compressed tar archives, and less
    frequently as zip files.

    One package typically contains an executable, and possibly some
    sample init files.  Another package contains the documentation
    specific to that variant.
    Another package often contains the full set of sources that was
    used to build the executable.

    It might seem silly to distribute the entire set of sources even
    when only a couple of things have changed.  It is not practical to
    distribute packages of only those modules that have changed,
    because there is no standard base version to serve as a reference.
    Even if there were, that reference version would itself be
    changing, so people would have to keep several copies of it on
    hand.

----------------------------------------------------------------------
Running different NOS versions with the same configuration

    It is sometimes possible to use the same set of configuration
    files and tree of directories with several versions of NOS.
    Some versions are so different, however, that they will not be
    able to understand each other's config files.  For instance, WNOS
    has trouble with the config files for JNOS.  The mailbox help
    files (in spool/help) are often quite specific to a particular version.

    Even worse, the commands that a NOS understands depends on what
    features were turned on when it was compiled.  If your config file
    contains commands to set up the NETROM interface, they will
    produce error messages if you run a NOS that was compiled without
    NETROM support turned on.  There isn't really any way to fix this
    problem, and it isn't all that unreasonable.
    
    The following are some known inconsistencies that could be fixed
    by someone who has the time to do it.  [Add to this list, please!
    Try to be as specific as possible.  The less time someone has to
    spend fixing something, the more likely it will be fixed.]

    -   The ftpusers file requires its fields to be separated by
	spaces in most versions of NOS.  You can't use tabs.

    -	The 'domain suffix' string must NOT have a leading period, but
	can (must?) have a trailing period.  If you do it wrong, some
	versions will complain, but most will just quietly fail to work
	properly.  I think it would be reasonable for the command to
	munge the string to look the way it should.

    -	In some versions of NOS, the arguments to some commands in autoexec.nos
	MUST be separated from each other by SPACES, not TABS.  Other
	commands don't care.  [I seem to recall the 'mbox' or 'netrom' command
	having this problem, but I can't swear to that. -- mg]

    -   There are minor variations in similar subcommands:

		ax25 retries
	vs.	netrom retry

	I'd vote for the plural form myself, because the singular form
	might suggest that it is a boolean that controls whether a retry
	should happen, whereas it is actually an integer count.

    -	The help strings that the commands print when given no arguments,
        as well as documentation, use "label" and "interface", "host",
	"address", and "destination" ambiguously.  "address" could be
	an IP address, an AX.25 callsign, or an Ethernet address.
	"label" usually turns out to be the name of an interface.

	Ian Wade G3NRW has suggested the following conventions in his
	paper in the 10th (1991) ARRL CNC proceedings.

	<callsign>     an AX.25 MYCALL callsign (e.g. G3NRW-5)

	<hostname>     a host name in domain.txt
		       (e.g. g3nrw or g3nrw.ampr.org.)

	<ipaddress>    an internet address (e.g. 44.131.5.2)

	<host>	       <hostname> or <ipaddress>

	<username>     a user at a computer (e.g. ian)

	<interface>    a device interface name (e.g. ax0)

	<ioaddress>    a device I/O base address (e.g., 0x3f8)

	<vector>       an IRQ level (e.g. 4)
		       [why not <irq> ? - mg]

    -   Different commands do different things when invoked with no arguments.
	This in itself isn't so bad, except that you can't always tell
	whether doing so had an effect or not.

    	Some commands print a help message when invoked with no arguments.
	Unfortunately, some simply print "needs at least one argument",
	instead of just telling what the choices are.  (If you type just
	"ax25" it says that, if you type "ax25 ?" it shows you the
	subcommands.)

	Other commands that can take arguments display some status
	information when they are invoked with no arguments.
	Unfortunately, some of them don't appear to do anything -- you
	just get another prompt.  This could happen if they would
	report some string and that string is empty, such as the
	"motd" command.  Such commands should really print something
	like "<not set>", instead of appearing not to do anything.

	Moreover, if a command that could take arguments *does* do
	something when invoked with no arguments, it should say that
	it has done it.  For instance, a command might set a variable
	a default value if invoked with the value omitted.  (No
	commands that I know of do this; omitting a value causes them
	to print the current value.)

	Note that commands can't tell if they are being invoked from
	autoexec.nos or by someone typing interactively.  This is
	probably why most of them aren't very verbose.


----------------------------------------------------------------------
Packet drivers

    The packet drivers from Clarkson and others are used to allow
    NOS to interface to many pieces of hardware and software.

    NOS can be interfaced to the G8BPQ switch and to BAYCOM modesms.

Why are there still compiled-in device drivers?  Why aren't they
implemented as packet drivers?

    From: "William Allen Simpson" <bill.simpson@um.cc.umich.edu>

    Part of the reason is that packet drivers don't separate the
    encapsulation (link-layer) from the actual device (hardware-layer) very
    well.  So, for example, when you have SLIP, PPP or NRS over two async
    ports, you would need to load all of the link-layer code twice.

    Also, a link-layer like PPP requires significant resources such as
    buffers and timers, which either need to be pre-allocated and managed
    for every device (wasting lots of CPU and memory), or managed under a
    single mechanism.

    BTW, Merit has built a PPP packet driver for NCSA Telnet.  It's over 100K,
    instead of the 24K we have inside NOS.

    Therefore, I believe that KA9Q (Phil Karn) decided on this architecture
    to save CPU and memory.  Remember, he started the program under CP/M!

    Now, there was some talk a year or two ago about a re-designed device
    driver mechanism to replace packet drivers.  But there was also talk
    about going to NDIS drivers.

    Which shall we do?

I can't seem to attach more that 3 packet drivers at once in NOS.

    That's true, you cannot attach more than 3 packet drivers.  This would
    have to be changed in the source code.  In fact, someone should probably
    finally sit down and make it correctly configurable with a simple compile
    time #define somewhere.

    -- Mike Bilow, <mikebw@ids.net>  (Internet)


----------------------------------------------------------------------
Common problems

Async interface loses characters

    If your machine can't field the interrupts from the serial port
    fast enough, it loses characters completely.  One symptom is that
    datagrams get retransmitted frequently over a SLIP or PPP line.
    In some NOSes this causes the TCP connections to reset
    automatically after getting a few datagrams across.  (TCP performs
    very poorly when the IP level datagrams are not delivered
    reliably, so it's best to just give up rather than waste
    bandwidth.)

    Another symptom is that garbled callsigns appear in the 'ax heard' list.

    One solution is simply to use a slower speed, like 4800 baud.

    A better solution is to replace the 8250 or 16450 UART with a 16550
    UART that has a built-in character FIFO.  This chip can buffer up
    to 16 characters while the machine is busy doing other things, so
    it relaxes the demand for prompt service.

    I've found that the JNOS i8250.c driver is slower than the others.
    It loses characters badly on a 9600 baud telephone modem, whereas other
    versions can keep up with no character losses at all.

    Rumor has it that DesqView may also cause problems if you run NOS
    in window 1.  Serial communications-intensive applications should
    ideally be run in window 2, as that one is actually optimized for
    serial comm.


    AG9V:

    I'm not sure why Johan's 8250 driver is slower -- I personally
    haven't noticed that -- but I do know that at least through his 1.04
    release the 16550 fifo was <not> enabled; the code would detect the '550
    but wouldn't do anything with it.  In JNOS 1.05, the fifo size
    can be specified as an attach command parameter.

Why do large amounts of core suddenly disappear?  For instance, I
started with 110K core, and FTP'ed a 1.5 Megabyte file off a LAN host
(14K bytes/sec transfer).  Core dropped to 30K. (using PA0GRI 2.0l)

    We found that the disappearing core was due in very large part to the
    number and size of Ibufs you've configured.

    What happens (I'm not a Real Programmer, so this may not be technically
    right on) is that when NOS needs another ibuf, it has to find a big
    enough unfragmented chunk in the heap to hold it.  If it can't find a
    large enough piece of memory, it goes to the core to get one.

    When you have ethernet-sized ibufs, it's quite likely that there won't
    be an unfragmented chunk big enough, so core is going to go away
    quickly.

    When we ran 1600 byte Ibufs, even starting with 190k coreleft, we could
    only run for about three days max before core would disappear.  We
    reduced the ibufsize to 448, which despite manual references to the
    contrary seems to be the minimum that works with an MTU of 256 and now
    we <never> see crashes resulting from loss of core (there are OTHER
    kinds of crashes, though...).

    So, sacrifice some performance on the ethernet by reducing your ethernet
    mtu, and your mss, to match what you'll really be running on the air.
    Then, set ibufsize to about that mtu plus 128.

    I haven't yet been able to determine whether the number of ibufs you set
    has any noticeable impact on this situation.  That's one for the coders
    to answer.

    John Ackermann   AG9V <jra@lawday.daytonoh.ncr.com>

    -Just one note.  The Ibufsize must be larger than your largest
    buffer size. (Not the same as but larger otherwise the SCC driver
    doesn't work properly.)

    So I assume you are running attach buffersizes just a little
    bigger or the same size as the mtu of the interface. ie 447 mtu
    for an ethernet port with a buffersize of 447.

    "Carl Makin" <makinc@hhcs.gov.au>

    Actually, I've been running attach buffers much larger than ibufsize;
    never knew that was a requirement.  And, it doesn't seem to affect
    things negatively.  When I ran big ibufs, they were bigger than the
    attach buffers and <that's> when I had the memory leak problems.

    It would be nice for One Who Truly Knows to fully document these buffer
    issues... their tuning is critical, but there sure isn't much to go on.
    Witness the statement in the asystat command section of the reference
    manual (that's been there for ages) that the number of software
    high-water-mark hits tells you whether you need to adjust the buffer
    size, and then refers you to the attach command chapter for further
    details, of which there are none.

    John


    Asy attach buffer doesn't care what the ibuf size is; they are fifo type
    buffers used during the interrupts, from which the asy rx process reads
    characters into mbufs. An asy buffer is allocated (with ints on) during
    the attach command, and is there for the life of the interface.

    Scc, packet and pi interfaces use the interrupt buffer scheme very actively
    for receiving of packets. They allocate buffers at interrupt time, and
    the queue need.
    The size of the buffer is somewhat complex. It needs to be the largest of

	-the largest ax25 paclen + about 100 (ax.25 header, actually 72 bytes max)

	-the largest ip mtu (if in vc mode over ax.25) + 20 (ip header) + about 100

	-the ethernet mtu + safety margin :)


    i have some written up in the latest draft of the jnos40 DE manual,
    i will include that in the docs for 1.05

    Johan


Why won't my PK-88 (and PCB-88)  send/receive a packet larger than 1048 bytes?

    The AX.25 spec limits packets to 256 data bytes, but we'll ignore
    that.

    It's a built-in limitation of AEA's.  They don't think it's a bug.
    Some Kiss implementaations have even more severe limitations. The
    Kantronics ROMS (at least the earlier ones) won't allow 1024.

    As far as I know the TNC2 TAPR ROMS do not have any imposed limitation
    other than memory. In your case you will have to complain to AEA or
    perhaps there is a later ROM for the 88.


---------------------------------------------------------------------
Compiling NOS

What compiler do I need to use?

    Most versions of NOS were developed using Borland (Turbo) C.

    Originally, Borland sold the compiler, assembler, debugger, and
    profiler as "Turbo C Professional".  Later they split the package into
    pieces.  Now the compiler is available for less than $100 as "Turbo
    C++".  The compiler and all the tools is available as "Borland C++",
    currently V3.1, and costs more than $300.  (For another $200, you can
    also get Borland's "Application Framework" for building windows
    applications, but that isn't needed for NOS.)

Compiler glitches

    Turbo C++ 1.0 cannot compile NOS, because the compiler is too buggy.
    (It compiles it, but the executable doesn't work right.)

    I believe that Turbo C++ 2.0 will successfully compile it.


    The BC++ 3.1 "-3" compiler switch is not safe with NOS.  This appears to
    be limited to certain specific modules, primarily ALLOC.C, but I have
    never managed to encapsulate the problem sufficiently.  What I think is
    happening is that the use of the "HUGE" keyword in some places causes a
    conflict with the "-3" switch.  Compiling ALLOC.C to assembly source with
    the "-3" switch will show some very funny results, for example.

    On the other hand, the "-Z" compiler switch, which used to be unsafe,
    is now safe under BC++ 3.1.  You win some, you lose some.

    -- Mike Bilow, <mikebw@ids.net>  (Internet)


What does 'linker fixup overflow' mean?

    >Fixup overflow at _TEXT:0092 , target=__MKNAME
    >c:\bc\lib\cl.lib in modeule FCLOSE.

    You need to force all of the MKNAME.C module to be in the _TEXT segment.
    This is explained in the voluminous comment I put into MKNAME.C.  You
    need to make sure that MAKEFILE invokes the compiler with the -zC_TEXT
    switch when compiling that specific module.

    What is happening is that library routine fclose() is making a call to
    __MKNAME(), which is declared to be "near pascal."  This means that the
    linker must be able to resolve an address for __MKNAME() within 64K;
    ts is a "linker fixup."  If __MKNAME() is more than 64K away from the
    place in flclose() where it is trying to call __MKNAME(), that is a
    "linker fixup overflow."

    This is not, by the way, a problem that can be finessed.  It must be fixed.

    -- Mike Bilow, <mikebw@ids.net>  (Internet)

What do I do when DGROUP exceeds 64K?

    The error happens because too many data objects (variables, strings, etc.)
    have been placed in the data segment, which is restricted to be only 64k
    bytes long.

    The easiest way to avoid this is to choose fewer options in config.h,
    so fewer data objects are defined.

    However, setting -Ff=511 or -Ff=255 in the makefile this will
    usually do the trick, too.

    Another way is suggested by Mike Bilow:

    The DFAR kludge that I developed to finally fix the linker error about
    DGROUP exceeding 64K found its way into the distribution release of
    PA0GRI NOS as of v2.0l or so.  Although it will work with Borland C++
    from version 2.0 or later (and this is correctly handled by a #define
    in GLOBAL.H), the compiler must be invoked with the "-Ff" switch from
    the MAKEFILE.  (Variants with the threshold specified, such as "-Ff=511",
    will work fine.)  I have not looked at Johan's [wg7j] source lately and I don't
    know if he included the DFAR kludge also, but it is generally more stable
    to use the DFAR kludge where the programmer picks what gets expelled into
    the far data segments rather than the Borland "-Ff-nnn" automatic far data
    threshold.  In my experience, "-Ff=nnn" will work with only sufficiently
    large values for "nnn," and will fail if smaller than 255.

    In other words, it works better to tell the compiler to be on the lookout
    for far data conversion with the "-Ff" switch, but to manually specify
    what gets moved using the DFAR kludge.  The "-Ff" switch with no value
    specified defaults to 32K, which doesn't move anything automatically.
    (Believe it or not, no one has yet put a static data object in NOS that
    is bigger than 32K.)

    -- Mike Bilow, <mikebw@ids.net>  (Internet)

Can NOS be made to use code overlays, so only the parts that are really in
use reside in memory?

    Making NOS work with code overlays is a discussion that comes up
    from time to time.  I spent a long time trying to get it to work,
    and all I ever had was a program that crashed almost instantly.
    The problem is that NOS changes the stack segment register on the
    fly, and the overlay manager has to know certain things about the
    stack in order to work.  The general consensus is that overlays
    cannot be done, although I have never conceded that and can't
    provide a counterexample.

    -- Mike Bilow, <mikebw@ids.net>  (Internet)


----------------------------------------------------------------------
DesqView, windows

    You have some immediate problem when trying to port NOS to DesqView or
    Windows.  First, Windows is somewhat unsuitable, since Windows apps
    expect to cooperatively multitask, and real-time performance is a thing
    requiring lots of kludges, even by Windows standards.  There are direct
    solution for doing this kind of Windows programming, most obviously
    writing a custom VxD virtual device driver, but you may find that you
    have rewritten a good chunk of Unix by the time this works.

    DV is more suitable, but still leads to problems.  It can be run on a
    very simple machine, although you don't gain much with DV until you have
    a 386 or better.  At this point, you are probably looking at the whole
    difference between a good DV setup and a good OS/2 setup being 4 MB of RAM,
    about $120 at current U.S. street prices.  I think DV is a really well done,
    even briliiant, product that fit a market niche that will soon disappear.

    -- Mike Bilow, <mikebw@ids.net>  (Internet)

    As I have mentioned before windows is not a multitasking system, it is
    cooperatively multitasking. This means that only one program can run at a
    time (period) That one program can give up control to Windows at selected /
    predetermined points, at that point Windows can give control to another
    app. That program in turn runs until it decides to give up control. If for
    some reason (error perhaps) it doesnt, nothing else (including windows)
    will run. If a program "hogs" control for say 1 sec, at 9600 baud thats abt
    1k data lost, for 5 sec its about 4.5k lost. It essentially could be done
    but there would be a huge risk of data loss and each process would have to
    be a window, as in the "dispatchable" unit of execution under Windows.
    Under OS/2 (for instance) it is a task not a window and OS/2 is a pure
    multitasking operating system, the timer task can not be stopped by a bad
    app, neither can the asy devices or the keyboard etc etc.

    Walt Corey [44.104.0.23] <kz1f@kz1f.ampr.org>


    There is another dos multitasker that would seem to fit the bill here
    it's Free,well documneted,source available also free and has almost all
    the facilitys needed built in. The program is called CTASK written by
    (I think) T. Wagner in Germany. I had considered a while back cutting the
    socket lib out of NOS and moving it to CTASK but the job looked a lot bigger
    that the time I had available.

    -- chrisc@london-pride.lmt.mn.org

Why does NOS implement its own task-switcher, when there are
several that exist and do a passable job?

    DOS NOS was done before DesqView was viable.

----------------------------------------------------------------------
Questions

    [ This section should summarize the topics that arise
      perennially on tcp-group. ]

How can I use NOS between computers over an RS232 wire link?

    NOS can use an asynchronous RS232 link by using a driver known as
    the async serial driver.  Look for the documentation under
    the 'attach' command, using the 'asy' driver.

    The link protocol uses the async driver.
    Whereas the async driver will move the characters from one machine
    to another, the link protocol interprets them.

    Most versions of NOS support one of two link protocols.

    SLIP is the most commonly used serial port link protocol.

    PPP is an alternative.  It is similar to SLIP, but permits the hosts
    to negotiate things like the interface's MTU automatically.
    If you don't know what that means, don't worry.  You're probably
    better of using SLIP.


Which of the RS232 signals are required on an async serial connection
(i.e., the minimum required)?

    RXD, TXD, and ground (pins 2, 3, and 7) are the minimum required.
    If both ports expect to be connected to a modem (most PC serial
    ports do), you'll have to use a null modem to flip pins 2 and 3
    (also 4 and 5; see below) between the ports.

    Beware that there is no hardware flow control with only these
    three signals.  Unless the link protocol does software flow
    control [I doubt that SLIP or PPP do], characters may be lost.

    If you also connect RTS and CTS (pins 4 and 5), NOS can use them
    for hardware flow control.

Does the async serial driver in NOS/NET do any hardware handshaking for flow control?

    Yes.  There is more than one implementation of the async serial driver,
    and each one handles handshaking differently.  The most widespread
    one is the one found in KA9Q NOS.  With it, you specify
    whether it should use RTS/CTS handshaking by putting a 'c' in the
    options word at the end of the attach command [before the IP address?].
    
    Another async driver, found in WG7J's JNOS [what others? GRI?],
    also supports RTS/CTS handshaking, but you don't have to specify
    that it should do so.  It automatically detects whether the other
    side is using flow control, and acts appropriately.
    If you do specify a 'c' in the 'attach' command's options word,
    the driver will ignore it, so it doesn't hurt to leave it there.
    [ Then how can I tell it to initiate the handshaking? ]

    This async driver can also use the RLSD (also called DCD) signal
    for flow control.

    


How do I use NOS as a router (gateway) between an Ethernet and an
Amprnet via a TNC?

    You may use any ethernet card that you have a Russ Nelson/Clarkson/FTP
    Inc. Packet driver for. I have used NE1000/2000, DEPCA, 3COM, and
    WD/SMC8003/8013. Drivers also exist for IBM Token Ring and Arcnet
    adapters.

    As in most TCP/IP implementations the "ifconfig <interface_name>" command
    allows one to assign independent (or the same) ip addresses for each
    interface. Gatewaying is supported by *either* doing an "arp ... publish"
    for the remote slip ip-address at the connected ethernet end, *or* using
    the "ifconfig encap" to encapsulate one subnet thru another ones ip
    address link. (this is the amprnet gateway system you have heard talked
    about.) My explanation presupposes you are familiar with most of the
    TCP/IP routing and addressing issues.

    Jack Spitznagel <jks@giskard.uthscsa.edu>


My machine crashes when I run it as an ethernet <-> slip router.

   Try getting a newer version of NOS (especially the KA9Q version).
   Also try running with handshaking totally disabled at both ends.

Why do I see garbled callsigns in the 'ax heard' list?

    This can happen because of errors in the received packet.  Bad
    packets occasionally occur in any transmission medium, especially
    on a shared radio channel.  If the sending stations TxDelay is too
    short, you may also see garbled packets.  Not all bad packets will
    appear in the various error counts kept by NOS.

    Garbled packets may also result if your serial port loses characters;
    see the section on 'async interface loses characters' elsewhere in
    this file.



How do I get a permanent IP address?

    Talk to the AMPRNET address coordinator for your area.
    A list of them is available in
    ucsd.edu:/hamradio/ampr_coordinators [?]
    The best way to find out, though, is to find other people nearby
    who are already running an AMPRNET host.

How do I set up a machine as a mail gateway?

    [this needs work - there MUST be a better way to do all this!]

    Briefly, add a REWRITE RULE to spool\rewrite FOR EACH HOST ALIAS.

    The machine must have a mail host address, one for each mail network
    that you want it to connect.  (A "mail network" is simply a bunch
    of machines that can, directly or indirectly, send mail to each other.)
    The machine considers itself to have only one real hostname,
    which is set (in AUTOEXEC.NOS) via the 'hostname' [?] command.
    We'll call the other names "hostname aliases".

    With NOS, you must take care that your gateway machine recognizes
    that the mail is destined for it, regardless of which of its host
    name the message was sent to.

    To begin with, the machine only recognizes mail addressed to its
    own IP hostname (the one that's set by the NOS 'hostname' [?]
    command).  To make it recognize its other host names, you have
    to add a rewrite rule in the file spool\rewrite that turns that
    hostname alias into the real hostname.

    If you fail to make your machine recognize all its hostname
    aliases, then when a message arrives for one of its aliases, it
    will forward the message to some other machine (usually to its SMTP gateway).
    Some machine down the line will realize that the message is
    supposed to go to your host, and will send it back there, creating
    a loop.  Eventually, some machine in the loop will notice that
    the message has been to the same hosts several times, and will
    (hopefully) return it to the sender.
    

What is "the mailer"?

    NOS can act as a maildrop, collecting and storing messages
    addressed to you.  There are several ways it can do this, such as
    SMTP and "conventional" amateur BBS mail forwarding
    protocols.  Also, people to connect or telnet to your mailbox can
    issue mailbox commands to leave you mail.  No matter how the mail
    gets there, it is stored in files in the spool/mail directory,
    where it stays until you do something with it.
    All messages addressed to a particular recipient are concatenated
    together in a single file.

    The mailer is a program, separate from NOS, that shows you the
    messages in a mail file.  If you are running plain DOS, you have
    to exit NOS to run the mailer.  (You can also use the 'shell'
    command to suspend NOS and get to a DOS command interpreter, but
    that takes a lot of memory to work.)  Then you run the mailer
    program to read your messages.  You can delete them, reply to
    them, forward them, and so forth.  When you're done, it updates
    your mail file, and queues any messages that you asked it to send.
    NOS will try to send the messages the next time you run it.

    You can run the mailer while NOS is running if you're running a
    multitasker like DesqView or DoubleDos.

    You can choose which program to use as the mailer by setting
    the DOS environment variable MAILER in your AUTOEXEC.BAT, as in

	SET MAILER=VIEW.EXE

    Some of the mailers that are available are:

    BM	    The earliest mailer that was included with NET/NOS.
	    Written by Bdale Garbee, N3EUA.

	    ucsd:/hamradio/packet/tcpip/bm

	    This was originally written as a quick-hack with style (or
	    lack thereof) reminiscent of /bin/mail on most Un*x
	    machines.  The whole motivation behind BM was to have some
	    way to test the SMTP client I had written for NET and the
	    SMTP server Phil had written and I had hacked on.  I still
	    remember how much fun it was sending the first mail
	    message from BM to the tcp-group list...  :-) And the very
	    serious discussion Phil and I had on the phone about
	    whether it was OK to call it 'BM' in a time period when we
	    were trying hard to be taken seriously by the packet
	    community at large... but hey, if you can't laugh at
	    yourself... :-)

	    Dave Trulli NN2Z did a bunch of work on BM at one point,
	    which is probably why it's still alive and in use.

    PCELM   A replacement for BM, popular in Europe.

    VIEW    ?
	    ucsd:/hamradio/packet/tcpip/bm

	    One small addition: The VIEW mailer is a full screen e-mail
	    user interface with many features like undigestifying,
	    queue manager, gateway specification etc. 

    NNTP readers

      -	I have not checked yet for newreaders specific to NOS,
	but the ones developed for PC-UUCP use should be usable.

	in /ibmpc/simtel20/msdos/uucp on doc.ic.ac.uk 
	(probably also on SIMTEL20 and its mirrors, like nic.funet.fi)
	It might need some modification to cooperate
	flawlessly with NOS NNTP but this should be minor.

      -	snews from John McCombs


      -	ftp.demon.co.uk:/pub/trumphurst/cppnws16.zip
	Nikki Locke <nikki@trmphrst.demon.co.uk>

Why does the 'shell' command just return without doing anything?

    This happens if there is not enough memory to run the DOS command
    interpreter as a child of NOS.  Rather than printing a message
    informing you of this, NOS just prints another prompt!

What is AMPRNET?

    AMPRNET is a network composed of amateur TCP/IP hosts whose names
    are in the .ampr.org domain, and whose addresses are assigned by
    the AMPRNET address coordinator (a person!).

    Although AMPRNET is technically a network, not all AMPRNET hosts
    can talk to one another.  Many people have begun to use landline
    gateways to connect the disjoint pieces of AMPRNET.

What is a gateway?

    A gateway is a host that joins one or more AMPRNET subnets to the
    rest of AMPRNET.  Loosely, an AMPRNET subnet consists of the
    AMPRNET hosts in a particular area, say, a city.    

    AMPRNET is a network composed of amateur TCP/IP hosts.  In theory,
    any host on a network like AMPRNET should be able to send IP
    datagrams to any other host on the network.  In practice, however,
    the network is fragmented into "subnets", which, loosely, is a set
    of machines that can talk to each other.  (The term "subnet" has a
    more specific meaning in TCP/IP, where it refers to a set of
    machines that have a common prefix in their IP address.  This
    simplifies routing; for more info, see the reference on gateways.)

    The hosts on a subnet may talk to each other via radio modems, TNCs,
    telephone modems, ethernet, wire lines, or just about any other
    way of moving bytes around.  (NOS is one of the few packages
    available to amateurs that can support this diversity.)
    Each city or town tends to develop such a subnet, because everyone
    in the locality can hear one another on VHF radio, and the phone
    calls are local, or they're even in the same building.

    If each of the hosts in a locality has a coordinated AMPRNET
    domain name and IP address, then that subnet is technically part
    of AMPRNET.  This means that other AMPRNET hosts on other subnets
    (i.e., other cities) could send packets to them, if only there
    were a way to get them between the two subnets.  To do this, there
    must be at least one host that can talk to both of the subnets,
    through which hosts on either subnet can send their packets to the
    other side.  Such a host is a gateway.

    In effect, a gateway turns the subnets into a larger network,
    called an "internetwork", or "internet".

What is an "Internet gateway"?

    An "Internet gateway", in AMPRNET, is a gateway that talks to
    other AMPRNET gateways by sending the packets over a landline
    network known as the Internet.  The Internet (capital I) is a
    world-wide academic and commercial network known as the Internet.

    Therefore, any host potentially can be a gateway if it is
    connected to some subnet of AMPRNET and to the Internet.
    In order to become an operating gateway, the other gateways must
    be told what the gateway's address is, and what subnets it knows
    how to send packets to.

    For more information on gateways, look in the following files
    that are available for FTP.

    minnie.cs.adfa.oz.au	gateways.023	(number changes with version)
    ke9yq.ampr.org

What's the difference between a gateway and a wormhole?

    Wormholes don't do routing; gateways do.

    A wormhole is just a two-way "data pipe", often a phone line, that
    can accept packets on one end, and spits them out at the other
    end.  There is only one possible destination.  It is like an AX.25
    digipeater, and in fact many wormholes are fashioned to look just
    like one.  (Another way to look at it is as a band opening on HF.)

    A wormhole doesn't know or care what is in the packets; in
    particular, it doesn't do any routing.  To use a wormhole, you
    have to know where its input port is so you can send your packets
    through it (as if it were a digipeater), and what stations are at
    the other end, so you can address packets to them.

    Gateways are more interesting than wormholes, because they can
    route packets sent into them to one of many different
    destinations, perhaps routing through other gateways on the way.
    Gateways form a true network, in the sense that you can just
    inject a packet into it, and it will figure out how to get it to
    its destination (if possible).

    Because they do routing, gateways have to know something about the
    packets you send through them, so they can figure out where to
    send it.  That is, you have to use a particular protocol that the
    gateway understands.


What parameters should I use for the netrom interface?

    netrom nodetimer 1800
    netrom obsotimer 1800
    netrom minquality 144
    netrom interface axip_place 230
    netrom interface diode_matrex 230       # direct rs232
    netrom interface back_bone 203          # just *two* radios talking
    netrom interface user_port 192          # lots of radios

    netrom ttl 24

    Since the timers will affect both the RF port and the encap ports I would
    suggest you set it to the same value that is used locally on the air.

----------------------------------------------------------------------
Wishes

    SV1XV:    Costas <kkrallis@leon.nrcps.ariadne-t.gr>

    As my job forces me to run SCO Unix Sys V on my main machine,
    I would like to find a STREAMS/socket driver to add ax.25 and
    KISS to the existing SCO TCP/IP services, but it seems nobody
    has written one yet.


----------------------------------------------------------------------
Machine Type:
Hardware Options:
        Display:
        DASD:
Network Hardware:
        AX.25:
        Network:
        Comm ports:
BIOS:
Memory:

OS:
Memory manager:
Device Drivers:
Shell:
Compiler Used:
        Compile Options:
        Patch Level:

----------------------------------------------------------------------

Glossary

    NET
    NETROM
    NOS

    RSPF
    	ucsd.edu:/hamradio/packet/tcpip/docs/rspf.doc
	ucsd.edu:/hamradio/packet/tcpip/incoming/rspf22p.txt

    RIP
    TCP
    IP
    Internet
    internet

----------------------------------------------------------------------
Bibliography

ARRL Computer Networking Conference Proceedings
    Available from ARRL HQ, Newington CT.
    Send mail to info@arrl.org for an automatic response pointing at
    more information about the ARRL.
    Some of these papers are available online in the directory
    ucsd.edu:/hamradio/packet/tcpip/docs.

    This list is not exhaustive; there are many other interesting
    articles, but these are the ones most relevant to NOS and TCP/IP.

    NOS Overviews and Documentation

	NOS Command Set Reference
			Ian Wade G3NRW			10th (1991)

	NOSVIEW: The On-Line Documentation Package for NOS
			Ian Wade G3NRW			11th (1992)

    	The KA9Q Internet (TCP/IP) Package: A Progress Report
			Phil Karn KA9Q    		6th (1987)

	Amateur TCP/IP: An Update
			Phil Karn KA9Q    		7th (1988)

	Amateur TCP/IP in 1989
			Phil Karn KA9Q    		8th (1989)

    Services and Protocols

	The Design of a Mail System for the KA9Q Internet protocol
			Bdale Garbee, N3EUA		6th (1987)
			Gerard van der Grinten, PA0GRI	

	Finger - A User Information Lookup Service
			Michael T. Horne, KA7AXD   	7th (1988)

	Callsign Server for the KA9Q Internet Protocol Package
			Doug Thom, N6OYU		8th (1989)
			Dewayne Hendricks, WA8DZP

	The Network News Transfer Protocol and its Use in Packet Radio
			Anders Klemets, SM0RGV	        9th (1990)

	A Routing Agent for TCP/IP: RFC 1058 Implemented for the KA9Q
	Internet Protocol Package			7th (1988)
			Albert G. Broscius, N3FCT

	Thoughts on the Issues of Address Resolution and Routing in
	Amateur Packet Radio TCP/IP Networks
			Bdale Garbee, N3EUA		6th (1987)

	Another Look at Authentication
			Phil Karn KA9Q    		6th (1987)

	LZW Compression of Interactive Network Traffic
			Anders Klemets, SM0RGV	        10th (1991)

	PACSAT Protocol Suite -- An Overview
			Harold Price, NK6K		9th (1990)
			Jeff Ward, G0/K8KA

	BULLPRO -- A Simple Bulletin Distribution Protocol
			Tom Clark, W3IWI		9th (1990)

    Macintosh

	KA9Q Internet Protocol Package on the Apple Macintosh
			Dewayne Hendricks, WA8DZP   	8th (1989)
			Doug Thom, N6OYU

	Status Report on the KA9Q Internet Protocol Package for the
	Apple Macintosh
			Dewayne Hendricks, WA8DZP   	9th (1990)
			Doug Thom, N6OYU

	Higher Speed Amateur Packet Radio using the Apple Macintosh
	Computer
			Doug Yuill, VE3OCU		10th (1991)

    Network design

	The Implications of High-Speed RF Networking
			Mike Chepponis, K3MC		8th (1989)
			Glenn Elmore, N6GN
			Bdale Garbee, N3EUA
			Phil Karn, KA9Q
			Kevin Rowett, N6RCE

	Design of a Next-Generation Packet Network
			Bdale Garbee, N3EUA		8th (1989)

	More and Faster Bits: A Look at Packet Radio's Future
			Bdale Garbee, N3EUA		7th (1988)

	Physical Layer Considerations in Building a High Speed Amateur
	Radio Network
			Glenn Elmore, N6GN		9th (1990)

	Spectral Efficiency Considerations for Packet Radio
			Phil Karn, KA9Q			10th (1991)

		This should be considered to be required reading.

	MACA - A New Channel Acess Method for Packet Radio
			Phil Karn, KA9Q			9th (1990)

	A Duplex Packet Radio Repeater Approach to Layer One
	Efficiency 
			Robert Finch, N6CXB		6th (1987)
			Scott Avent, N6BGW

	A Duplex Packet Radio Repeater Approach to Layer One
	Efficiency, Part Two
			Scott Avent, N6BGW		7th (1988)
			Robert Finch, N6CXB


    Network Implementation

	Packet Radio at 19.2 kB -- A Progress Report
			John Ackermann, AG9V		11th (1992)

	Implementation of a 1Mbps Packet Data Link
			Glenn Elmore, N6GN		8th (1989)
			Kevin Rowett, N6RCE

	Hubmaster: Cluster-Based Access to High-Speed Netowrks
			Glenn Elmore, N6GN		9th (1990)
			Kevin Rowett, N6RCE
			Ed Satterthwaite, N6PLO
		    		
	Recent Hubmaster Networking Progress in Northern California
			Glenn Elmore, N6GN		9th (1990)
			Kevin Rowett, N6RCE

	The 56 kb/s Modem as a Network Building Block: Some Design
	Considerations
		    	Barry McLarnon, VE3JF		10th (1991)


	Digital Networking with the WA4DSY Modem - Adjacent Channel
	and Co-Channel Frequency Reuse Considerations
		    	Ian McEachern, VE3PFH		10th (1991)

	A Full-Duplex 56kb/s CSMA/CD Packet Radio Repeater System
			Mike Chepponis, K3MC		10th (1991)
			Lars Karlsson, AA6IW

	A High Performance, Collision-Free Packet Radio Network
			Phil Karn KA9Q			6th (1987)

	Adaptation of the KA9Q TCP/IP Package for Standalone Packet
	Switch Operation
			Bdale Garbee, N3EUA		9th (1990)
			Don Lemley, N4PCR
			Milt Heath

    Hardware

	The KISS TNC: A Simple Host-to-TNC Communications Protocol
			Mike Chepponis, K3MC		6th (1987)
			Phil Karn, KA9Q

	The Ottawa Packet Interface (PI) A Syncrhonous Serial PC
	Interface for Medium Speed Packet Radio
			Dave Perry, VE3IFB		10th (1991)

	HAPN-2: A Digital Multi-Mode Controller fo the IBM PC
			John Vanden Berg, VE3DVV	11th (1992)

	The PackeTen system - The Next Generation Packet Switch
			Don Lemley, N4PCR		9th (1990)
			Milt Heath

----------------------------------------------------------------------
