Using SLIP/PPP Emulators (TIA or SLiRP) on Alumni/Alumnae

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Introduction

The purpose of this document is to detail the settings peculiar to Caltech needed for the various pieces of software needed to use SLIP/PPP emulators such as TIA or SLiRP on the Macs and PCs running Windows (3.1, 95, or NT). The purpose of this document is to list the modifications peculiar to the Xyplex and alumni/alumnae in particular.

Background Questions

  1. What is a SLIP/PPP emulator? SLIP/PPP emulators are a special class of software which allows the user to have most of the benefits of a SLIP or PPP account given only a normal Un*x shell account. This includes the use of graphical browsers, such as Mosaic or Netscape over a dial-up line.
  2. Why use an emulator instead of a real SLIP/PPP account? Due to various managerial and financial constraints, we don't have access to the CCO's SLIP/PPP pool of lines. For those in a reasonable calling area, an emulator is the only other alternative which allows you to use your alumni or alumnae account (which is the equivalent of a "shell" account, if you went to an outside Internet Service Provider or ISP) in the same manner (for the most part) as a SLIP/PPP account. You can, with this kind of software, have most of the advantages of both types of account.
  3. What things don't work with an emulator instead of SLIP or PPP? The main difference is you don't really have an accessible IP for the most part; you piggyback on the host's IP address. This makes it difficult to be, say, an FTP server. SLiRP is supposed to allow you to do this, but I haven't spent enough time to figure out how to make it work yet and know its limitations.
  4. What kind of modem should I get? Any 14.4K (V.32bis) should work. You do require a Hayes compatible modem to use most modem scripts (but not necessarily to connect), however, almost all modern modems would fit in this class (you'd have to try really hard to not get a Hayes-compatible modem today). All of these modems will also usually have V.42bis and MNP 5 compression, as well as MNP protocol. V.34 modems (28.8K) should also work, although Caltech's main pool is 14.4K only and will upgrade only at the rate of attrition. 14.4K connections, until the bugs are worked out more thoroughly in the chips. An external modem with indicators and a convenient power switch is better since it allows you to know what's going on and more complete control things if something goes wrong (you can always power down the modem which should hang up the call).
  5. What's a DNS and what do I put in for DNS values? DNS stands for "Domain Name Server." A simple analogy is to think of the DNS (which is simply some machine which has been designated as such) as sort of the TCP/IP equivalent of directory assistance: it allows you to look up a nmae (such as alumni.caltech.edu) and turn it into an IP address (which is the way network traffic needs to be addressed in order to get to the correct destination), such as 131.215.50.230. What you put in when you fill in a DNS IP address, is basically the TCP/IP equivalent of 411 or 555-1212. Values (as of this writing) you should use for DNS addresses (in rough order of preference) are 131.215.139.100, 131.215.48.151, 131.215.50.230, 131.215.147.254, 131.215.139.43, and 131.215.145.137. You need only put in one, although two is a good number (in case the first server is down).
  6. What's my IP address? This depends somewhat on the software you're using. Specific notes will be given below, but values you might want to use or see
  1. are 131.215.50.230 (alumni's address if you're running on alumni), 192.0.2.1 (nowhere), 10.0.2.1 (default used by SLiRP).
  2. Should I use SLIP or PPP? In general, PPP is better than SLIP. However, you may want to see the sections in individual operating systems below for personal experiences and biases.
  3. Should I use SLiRP or TIA? Unless you're using an old implementation and you have your own TIA license, you should use SLiRP. TIA is no longer a supported product, so all new development for scripts you obtain here will use SLiRP. In addition to being free, SLiRP also provides a number of advantages over what TIA used to provide; in particular it allows port redirection so that you can be an FTP or web server during the time you're logged on (Note that this doesn't mean you should use the CCO modems we don't pay enough for all day or night to run your server!). X-windows connections may also be forwarded over SLiRP.
  4. A brief overal view of how things look: From the standpoint of view of your machine, there are two basic "layers" of software you need to be concerned with. The first layer is a TCP/IP stack, which allows your machine to in essence speak the language of the Internet (it's more general than that, but that description will suffice for these purposes). The second "lower" layer you need is a SLIP or PPP protocol package, which is the medium via which the TCP/IP protocol packets are moved from your machine over a serial line (modem phone line in this case) to where they need to go.

For platform-specific information, click here for Mac, here for Windows 3.1 (including Quarterdeck) , here for Windows '95, or here for Windows NT information and files.

Mac Information and Files

For a list of the pieces needed and where to get them, see Appendix A, an excellent document from Brian Kendig (bskendig@netcom.com) on Netcom (a major Internet access provider), and kindly passed on to me by fellow alum Diana Finley (finley@alumni.caltech.edu ). It is an excellent base guide for setting up to use SLIP or PPP on the Mac. This document will be presented as a brief commentary on the instructions in Appendix A, noting modifications when applicable in order to run properly on Caltech's modem pool talking to alumni. The "free" stuff you need can be downloaded by clicking here.

In terms of the two-layer model presented above, Macs have two choices when it comes to the TCP/IP layer: MacTCP (aka "Classic" networking) or OpenTransport. Note that the choice here really influences all networking connections into the Mac in question (i.e., it includes AppleTalk as well as TCP/IP). At the lower level (which only affects TCP/IP) the choices are many and are determined first by whether one chooses SLIP or PPP, and second, by availability and personal preference.

  1. So, what about OpenTransport? OpenTransport 1.1.2 is the current version of OT and, contrary to earlier versions, is quite stable. It is the only choice if you have a "newer" machine. For older machines, (68030 or higher with 32-bit clean ROMs) I would still recommend OpenTransport if you do not already have a stable MacTCP ("classic networking") configuration. For 68030 machines which do not have 32-bit clean ROMs (not Connectix software upgraded ones), it is a tossup as 7.5.5 supports both styles of networking and it is the last version of system software which will run on these machines. For lower than 68030 machines, classic networking is the only choice.

General Questions (apply to either SLIP or PPP)

  1. Should I use SLIP or PPP (Mac answer)? In the old days, this answer was fairly complicated. Today, the choice is almost exclusively in favor of PPP due to stability, speed, and availability of both current software and future devlopment.

SLIP Questions

  1. What are my choices for SLIP software on the Mac? The two most popular choices are MacSLIP and InterSLIP. InterSLIP is free, and is the only SLIP package discussed here since it is the only one the author has had significant experience with.
  2. Do I have to open the InterSLIP setup application each time to access SLIP? No, but automatic mode (in which your application just tries to establish a TCP/IP connection and when MacTCP or OpenTransport calls and notes that it is configured for SLIP with InterSLIP, in turn calls the InterSLIP setup program) should be used only if you know what you're doing and are willing to take the consequences if something goes wrong (hung system or crash, sometimes). You can more easily see the progress of the negotiation and disconnect more cleanly if something goes wrong If you're using InterSLIP 1.0.2d2 (no longer available from InterCon) be sure to read the notes on InterSLIP settings (especially the footnotes).
  3. What if something goes wrong? With the enclosed scripts, usually being patient will work. If you followed the recommendations of Question 2, you can use the disconnect button on the InterSLIP setup opening dialog (if you didn't open up InterSLIP, you can usually try to do so now and proceed; it's just that some applications don't adapt as well to the connection being refused and can crash your system). You'll probably have to wait for the InterSLIP script to time out as it's not in a 'predictable' state, but it should eventually go idle and the connect button will become highlighted instead of the disconnect button. You can then try the connection again. If this doesn't happen, you should probably reboot your machine before trying again.
  1. My connection seems hung. This is fairly rare with newer software; somewhat common with InterSLIP and an old version of TIA which is no longer supported. Recommendation: change over to PPP.

PPP Questions

  1. What are the current choices for PPP software? In the beginning, there was MacPPP. MacPPP underwent a number of variations, of which the two primary variants were called MacPPP and FreePPP. MacPPP was eventually used by Apple in its Internet Connection Kit. FreePPP has continued to be developed independent of Apple in the meantime. Apple in the meantime developed OT/PPP in conjunction with its move to the OpenTransport networking architecture. Many of the people that worked on FreePPP also worked on OT/PPP, or so it said. All of these variations exist in at least one form in a "free" implementation. Due to the complexities of navigating the Xyplex switch, the author strongly recommends OT/PPP as the preferred PPP implementation as of this writing.

Notes on OpenTransport

Under Construction

Notes on OT/PPP

Under Construction

Notes on InterSLIP settings

The values in the InterSLIP configuration dialog are those that in most cases are identical to what you need to use (those that are optional are labeled such). The dialog box shown is for InterSLIP 1.0.2d2 (a beta test version) and contains a few items which are different from those available in 1.0.1; these differences are noted below when applicable. This dialog box is accessible by double-clicking on a configuration in the initial dialog box (Figure 1) when InterSLIP setup is opened, or by selecting NewN from the File menu. Be sure the upper triangular button is in the orientation shown, or now configurations will be listed (click once to toggle orientation).

  1. Serial Port: Most machines are set up so that your modem is hooked to the modem port (has the picture of the phone above it). The modem port gets slightly higher priority, so this is what you should do unless you have a real good reason for not doing so.
  2. Baud Rate: There are actually at least three 'baud rates' that are involved in a modem connection: There is the speed between your Mac and the modem; there is the speed over the phone line; and there is the speed between the modem at the other end and whatever it's connected to. The limiting (smallest) speed among these should be the speed over the phone line (unless you have a slow machine, say less than 68030 class, or a very busy one, in which case you should consider un-busying it while you're on-line); this speed is thus usually limited by the "speed" of the slowest modem in the connection path. The maximum modem-to-modem speed you can talk to the Caltech modem pool is currently 14.4K. You probably shouldn't be using SLIP if you don't have at least a 9600 baud modem. The baud rate you set here should be at least 2x, and preferably 4x the modem-to-modem speed as that is the speed characters can get dumped to you since the data is often compressed (except when downloading files already compressed) by the transmitting modem and uncompressed by the receiving modem. The value shown here is appropriate for a 9600 baud modem. It normally does no harm to set this as high as possible, unless your machine is slow (as noted above) or very busy, and you get a lot of errors or dropped characters. Typically, any transient conditions are intended to be handled by flow control methods regardless of the speed.
  3. The Data Bits, Stop Bits, and Parity settings are those of the Xyplex modem pool and must be matched.
  4. You must have a Hardware Handshaking cable and have hardware handshaking enabled for your modem.
  5. The Speaker option is personal taste but is sometimes useful in knowing what's going on.
  6. The Disable Automatic Connection is only present in InterSLIP 1.0.2d2. It prevents you from starting up InterSLIP through just opening a TCP/IP application and initiating a connection: normally the application will call MacTCP who will in turn call InterSLIP to establish the SLIP connection. Although this sounds really neat, it doesn't work very well if your scripts are not robust enough to handle problems (like busy line, modem negotiation problems, mis-typed passwords, etc.) and can cause system crashes. Leave this enabled (unchecked) if you're using 1.0.2d2 only if you know what you're doing and are willing to take the consequences1.
  7. IP Address: The Netcom document states to use 192.0.0.0 or that it is probably not important. It actually is for some applications as this number is fed to MacTCP and is the number that some sites (Apple's FTP sites come to mind) get when they ask for your node number and then try to do a nameserver lookup to see if you're coming from a reasonable place and will complain if they can't get a name (as would be the case with 192.0.0.0). To be honest, use caltech.alumni.edu's number which is where you're really coming from when you connect to those sites.

Most of the other settings should be self-explanatory, or the explanation on the diagram should be sufficient.

Windows 3.1 Information and Files

Click here to download script and configuration files for Trumpet Winsock , or here to obtain the script file for Quarterdeck's QWINSOCK .

Windows '95 Information and Files

Click here to download script files for Windows '95 .

This file is simply the download scripting file to connect through the Xyplex and firing up SLiRP. To use it, you need to have installed the Dial-up Scripting tool which is not normally installed with Win95. If it is installed, you should be able to see it in the Start Menu as in Figure 8 below.

If the Dial-Up Scripting tools have not been installed, see the file \ADMIN\APPTOOLS\DSCRIPT\DSCRIPT for instructions on installing the necessary software. You must also be sure the Dial-up adapter is chosen as a binding in the Networks control panel (see Figures 9).

You must also configure your TCP/IP binding options to include name servers and to get an IP address from the erver (for SLiRP) or manually as 192.0.2.1 (for TIA); see Figures 10 & 11.

You should then place the ALUMNI.SCP file you downloaded in the \Programs Files\Accessories directory on drive you have Win95 installed on (the directories should already be there). If you then choose the Dial-Up Networking item off of the Start Menu (Figure 8), you should find an Alumni object which you can right-click on to bring up a menu from which you can choose "Connect."

Windows NT Information and Files

Click here to download script files for Windows NT 3.5.1 or 4.0. You may also use the Win95 scripting files with Windows NT 4.0 (or so the documentation implies).

Appendix ATIA and the Mac 


                How to TIA
           (revision of 31 December 1994)
         by Brian Kendig (bskendig@netcom.com)

I've seen a lot (and I mean, a LOT) of posts from Mac users who are
completely baffled as to how to get TIA working with their Macs. For a
while, I was one of those baffled users. I spent some long hours
puzzling over it before I finally got it working, so I put together this
information to help other people avoid the same problems I stumbled
through. It's really not a difficult process, but it can be confusing
if you haven't done it before.

(Thanks very much to Bill Arnett (billa@netcom.com) for his revisions to
my original instructions!)

In case you're wondering what TIA is, let me explain  it's a Unix
program that you run on a normal dialup shell account in order to have
TCP/IP access very similar to what SLIP gives you. In other words, if
right now you run a terminal program and dial in to your Unix system
over a modem, then TIA will let you run Telnet, ftp, NewsWatcher,
Mosaic, Netscape, and other networking software on your Macintosh, all
at the same time, as if you had a full (but slow) connection to the
Internet. For more general information about what TIA is and how to get
it, check out "http://marketplace.com/" (by running "lynx" on your Unix
system or using Mosaic or Netscape if you have access to them), or ftp
to marketplace.com and read the file "read.me" in the "tia" directory.


              

First, here are some steps you can do before you register for your
fourteen-day TIA evaluation copy. These are things you'll need to do
anyway before you can use TIA at all, so it makes sense not to start the
evaluation period counting down until after you've done them.

You might want to start by buying a copy of Adam Engst's book _The
Internet Starter Kit_. It comes with a floppy that contains MacTCP,
InterSLIP, and other handy software, and the book itself is especially
good for novices. If you purchase this book with its accompanying disk,
you won't have to worry about finding the software below from other sources.

Here is the software you'll need to have to start out with:

 o "MacTCP", Apple's networking software. This is the ONLY commercial
   software you'll need for any of this. MacTCP comes with System
   7.5, and it can also be purchased separately from Apple or gotten
   with Adam's book. It is not available for ftp on the Internet.

 o "InterSLIP", a free product from Intercon Systems which lets you run
   TCP/IP over your phone lines. You can download InterSLIP from any
   of the usual Mac ftp sites; on the sumex mirrors (try ftp.hawaii.edu;
   it's fast) it's info-mac/comm/tcp/inter-slip-installer-101.hqx.
   InterSLIP is also available with Adam's book, or directly from
   InterCon (ftp.intercon.com) in "InterCon/sales/InterSLIP" as
   "InterSLIPInstaller1.0.1.hqx".

 o Get a copy of NCSA Telnet 2.6. This is available from
   zaphod.ncsa.uiuc.edu in Mac/Telnet/Telnet2.6/Telnet2.6.sit.hqx.
   Telnet is a good TCP/IP program to use to test whether your
   connection is working.

On your Unix system, find out what your name server addresses are.
There will be probably one, two, or three computers set up to figure out
what the real IP addresses are of any host names you use, and you'll
need to give the numeric IP addresses of those computers to MacTCP and
InterSLIP. Contact your Unix administrator if you need help with this.
Also, find out the numeric IP address of the computer you normally log
into, so you can tell NCSA Telnet where to find it later if it can't get
to the name servers for some reason. (For example, here on Netcom, the
nameservers are netcomsv.netcom.com at 192.100.81.101 and ns.netcom.com
at 192.100.81.105, and I also jotted down the address of
netcom7.netcom.com, which is 192.100.81.115.)


              

Install InterSLIP by running the installer you've downloaded, reboot,
then go into the "InterSLIP Setup" program. Select "New" from the File
menu, enter any name for your new configuration, then double-click on
the name when it appears in the main window. In the ensuing modal
dialog, you'll probably only need to set a few things:

 o Your baud rate. For a 14.4kbaud modem, try setting this to 19200 (it
   worked for me); if that doesn't work you can always try 9600 later.

 o An IP address. You can enter anything here, since TIA doesn't set up
   an individual IP address for you. This field usually gets ignored.
   You should probably set this to "192.0.2.1", which is an address that

   is actually defined to mean "nothing". Setting it to something simple
   such as "1.1.1.1" should also be okay.

 o The numeric IP address of one of your name servers (preferably your
   "primary" name server), which you found a few paragraphs ago.

 o The "MTU Size". TIA documentation recommends setting this to 1500.

Leave the "Dial Script" and "Gateway" set to "Direct Connection".


              

Now, install MacTCP, reboot, and open its control panel. Click on the
InterSLIP icon that appears there, then click on "More".

 o Set the radio buttons under "Obtain Address" to "Server". I don't
   think this matters, but this is what has worked for me.

 o Set the "Class" under "IP Address" to "C".

 o The entries for "Domain Name Server Information" can be a bit
   tricky. First let me show you what I set mine to, then I'll
   explain. Remember that I found out my nameservers are
   192.100.81.101 and 192.100.81.105:

      netcom.com       192.100.81.101
      .           192.100.81.101
      .           192.100.81.105

   The first line should give your default domain (usually the last
   two parts of your hostname, such as "netcom.com" or "princeton.edu")
   and the address of your primary nameserver. Each line after that
   should give a dot (".") and the addresses of each of your nameservers.
   This means that if I try to connect to a system ("netcom4") but I
   don't give its complete name, it will tack on the default domain
   (hence "netcom4.netcom.com") and look it up with the primary
   nameserver. If I try to connect to a system by giving its complete
   name, the nameservers by the "dot"-entries will be used to look it up.

   Click the "Default" radio button by the first entry in your list.

After all this is set, just click "OK", then reboot to apply the changes.

              

Now your Mac should be all set! After it reboots, you can go about
setting up TIA on your Unix shell account. The TIA documentation is
very thorough and helpful about how to do this. Register for your
fourteen-day evaluation license, and get to the point where you can run
"tia" from your Unix prompt and have it reply "Ready to start your SLIP
software." Note that if you ever want to stop TIA and get back to a
Unix prompt, just type Control-C slowly five times, such that more than
two seconds go by between the first Control-C and the last one.

Oh, and make sure that your terminal program isn't set to automatically
hang up when you quit out of it; you will need to be able to quit out of
your terminal program without killing your dial-in connection to your
Unix host. (I know for a fact that there's an option in Zterm,
MacLayers, and Microphone that tells them not to hang up when you quit;
look for something like "Drop DTR on Quit" and turn it off.) Right now,
quit out of your terminal program then run it again, and if you find
yourself still going as if you had never quit, then you should be okay.

Okay. Now for the moment of truth.

At a Unix prompt, run "tia" (or whatever the executable is named). It
should reply "Ready to start your SLIP software."

Quit out of your terminal program, open "InterSLIP Setup", make sure the
name of the configuration you created earlier is selected, and click the
"Connect" button. If all goes well, then the word "Connected" should
appear at the top of the window. Note that as long as this says
"Connected", you will not be able to run your terminal program, since
InterSLIP has grabbed the serial port. For example, my copy of Zterm
will hang if I try to run it while InterSLIP has the serial port.

Now run NCSA Telnet. Try to open a connection to the Unix host you
usually connect to. If it fails to connect, then try again, this time
giving the numeric IP address of the Unix host; if it fails with the
name but works with the number then this means that you haven't set your
name servers correctly in the MacTCP control panel or in InterSLIP.

If you've run into problems before this point (InterSLIP doesn't
connect, or NCSA Telnet gives you errors), and you can't figure out what
the problem is, then post on comp.sys.mac.comm to ask for help.
Describe exactly what step of the installation you got up to before
things started going wrong.

On the other hand, if things work for you, then you're all set!
Disconnect from InterSLIP and go back into your terminal program to
download a copy of Dartmouth's "FTP" program from a Mac ftp site, and
try to use that to download a copy of Netscape. Being able to finally
run Netscape on your Mac is a fitting reward for getting all of this to
work successfully.


              

You might also want to set up InterSLIP to dial in automatically for you
and run tia without any need for intervention on your part. One example
of how to do this is available via ftp to ftp.netcom.com, as
"/pub/mealiffe/netcom/tia-interslip-script". Put that file into the
folder "System Folder:Preferences:InterSLIP Folder:Gateway Scripts" on
your Mac. You might have to change its type/creator to CNFG/ISLP. It's
a text file, so you can edit it if necessary. Make any necessary
changes to your Unix .login file so that you will always automatically
get to a Unix prompt when you log in. If your prompt does not end in a
percent ('%') character, then use a text editor to edit the script you
just downloaded to put the correct character there (it tells you where
to make the change). I also had to add an extra zero to the number
after every "matchread" statement in the script (for example, where it
said "matchread 50" I made it "matchread 500") to prevent my connections
from timing out so easily before they had finished connecting. Also,
make sure that the TIA application on your Unix account is named just
"tia", since that's what the script will try to automatically run for
you (unless you change the script).

Go back into the InterSLIP Setup application and edit your
configuration: set the Dial Script to "Hayes Compatible" and enter the
Unix dial-in phone number, and set the Gateway Script to the script you
just downloaded and edited. If all went well, then whenever you try to
run any TCP/IP application on your Mac when you're not already
connected, InterSLIP will automatically dial in for you and establish
the connection. Easy as that. :-)


              

Don't forget to post to comp.sys.mac.comm for help if you can't get this
to work  if you run into a problem, chances are other people have,
too. A lot of people have sent email directly to me asking for help
with all sorts of TIA issues; so many people, in fact, that I've been
TOTALLY swamped, and I'm sorry to say that I won't reply to any future
requests for help setting up TIA unless you want to pay me for it. ;-)
I'm not the only person on the net who knows how to set this up! If
there are any unclear or incorrect parts of these instructions, though,
please don't hesitate to let me know, and I'll fix them.

Good luck, and happy SLIPping!


_/_/_/  Be insatiably curious.         Je ne suis fait comme aucun
/_/_/  Ask "why" a lot.        de ceux que j'ai vus; j'ose croire
_/_/              n'etre fait comme aucun de ceux qui existent.
 /  Brian Kendig     Si je ne vaux pas mieux, au moins je suis autre.
 /  bskendig@netcom.com                     Rousseau
   ftp://ftp.netcom.com/pub/bs/bskendig/home.html
  1. 1 Experimentally, 1.0.2d2 seems to have nameserver problems for the initiating connect in automatic mode also although it is not clear what problem is.