Dialing into Athena (AC-15) Dialing into Athena (AC-15)Note: This document refers to a deprecated service and exists purely for reference purposes.
This document explains how you can gain access to Athena facilities via dialup when you are away from the campus.
An alternate dialup method is Tether, MIT's remote-access dialup service providing PPP connectivity to MITnet. Tether provides high-speed, point-and-click access to MITnet and the Internet from home or on the road. It supports the Point-to-Point Protocol (PPP) and ARA (AppleTalk Remote Access) over analog lines at speeds up to 28 kilobits per second. The current release of Tether does not support ISDN access. See the Tether documentation at http://web.mit.edu/is/help/tether/ for more information. (This Dialing into Athena document covers Athena dialup.)
Note: If MITnet is installed in your dormitory or living group, you can access Athena over the network without dialing up.
To dial up to Athena, you need:
You follow three basic steps to dial into Athena:
These steps are described in detail in separate sections.
When you dial into Athena, the connection you establish is a terminal-oriented session rather than a window-based session. A dialup session differs from a workstation session in several ways.
NO X WINDOWS. Since in a dialup connection you don't have an X server, and phone lines are not fast enough to support one, you won't get multiple windows. Instead, you have a character-based display with (possibly) some very limited graphical features. If you want to run an X application or use a computation-intensive program (e.g., Maple or MATLAB), you should always work on campus on a single-user Athena workstation, rather than a dialup server.
Many programs that you may use in X versions also have terminal-oriented versions for use in a dialup session:
| X version | Terminal-oriented version |
|---|---|
| xmh | inc, comp, scan, repl, show |
| help | help -tty |
| xrn | rn |
| emacs & | emacs |
| xcalc | dc |
| ez | (no text version) |
| xman | man, apropos |
LIMITED TEMPORARY FILE STORAGE SPACE. When you dial into Athena, you are time-sharing a single server with many other users and you do not have sole access to the temporary storage on the server. Those spaces fill up easily, and once they are full, no one on that dialup machine can perform such tasks as autosaving Emacs buffers, and no new users can login. If you are on dialup and need to save large temporary files (e.g., files you ftp from somewhere else), save them in /mit/bitbucket rather than in /tmp or /usr/tmp.
DIFFERENT ZEPHYR BEHAVIOR. Because there is no X-windowing capability over dialup, the system cannot display individual zephyrgrams as separate windows; by default you do not get Zephyr messages. However, you can have zephyrgrams appear as text messages on your terminal screen. (See the section Zephyr Over Dialup).
DIFFERENT STARTUP FILE. You tailor your environment in a slightly different way for a terminal-oriented session than you do for a window-oriented session. In particular, instead of executing the commands in a file named ~/.startup.X (this file is used for window sessions), the dialup session executes the commands in the file ~/.startup.tty (this applies to any remote login). Your ~/.environment, ~/.path, and ~/.cshrc.mine files, however, are all executed in either type of session. (If you want to issue some commands selectively in those files, you can take advantage of the XSESSION environmental variable to test whether or not you have initiated a window session.) Dotfiles: Customizing Your Athena Session (AC-16) contains more details and useful examples. This manual is available in the Copy Tech Center in 11-004.
TIME OUT. In a dialup connection, you are automatically logged out if your session has been idle for more than 90 minutes. (On the athena-x server, due to a bug in time-out implementation, if any of your windows are idle for 90 minutes, you are logged out.)
To dial into the system, you need a terminal (or terminal-emulating device) and a modem or digital phone -- and of course, a working phone line! Depending on how your terminal and modem are related to each other, you may also need various cables (e.g., an RS232 cable to connect the terminal and modem).
TERMINAL. The terminal can be either an actual terminal, for example a VT100, or a computer, such as a Macintosh or IBM PC, that can emulate a terminal by using communications software (e.g., Kermit, ProComm, White Knight, or Versaterm). For dialing into Athena, you should have a terminal or computer that emulates one of the terminal types listed in Athena's /etc/termcap file. VT100 emulation is recommended since programs such as rn (netnews reader) and emacs perform optimizations for slow connections when VT100 emulation is being used.
MODEM. There are two different kinds of modems: an "internal" modem, built directly into a terminal-emulating computer; or an "external" modem, distributed as a separate piece of equipment. Note that the ISDN digital phones contain an element that functions as a modem, so if you are using one of these phones you should treat the phone itself as an "external modem," even if your computer has a built-in modem.
CONFIGURING YOUR DEVICES. Before you can connect to the dialup service, make sure that your terminal and modem are configured correctly. Check the manuals that come with your equipment for instructions.
TERMINAL CONFIGURATION. Use the following settings for your terminal or terminal emulator:
| Parameter | Setting |
|---|---|
| Data Bits | 8 data bits |
| Stop Bits | 1 stop bit |
| Parity | no parity |
| Duplex | full duplex |
Note in particular that you should not use 7 bits or even parity.
The use of hardware flow control is recommended. If you are using a modem and the modem supports flow control, set your terminal to match the type of flow control used by the modem. Consult the instructions that come with your modem for a section on flow control. Hardware flow control is often referred to as RTS/CTS or EIA flow control.
DIGITAL PHONE CONFIGURATION. You can set the digital phone options from the phone's dial pad. The handset must be in the cradle and the speaker must be turned off to set options from the dial pad. Take the following steps (in order):
If you have a model 7506 or 7507 digital telephone, follow the instructions on the phone's display at this point, pressing * to change, 0 to skip, and # to save the settings specified below.
| Data Mode: | DX25 |
| Data Rate: | 9600 |
| Parity: | space |
| Local Mode: | CMD |
(Note: Some software/devices cannot keep up with such a high data rate. If you notice lost characters in your connection, try using a lower speed.)
Or you may continue with these steps:
The telephone automatically stores your selections and exits program mode after the last step.
ISDN digital telephones support flow control. If your terminal and RS232 cable support hardware flow control, enter the following commands at the CMD prompt on your terminal:
CMD: set rec.flow eia CMD: set trans.flow eia
If your terminal does not support flow control, enter the following commands at the CMD prompt:
CMD: set rec.flow off CMD: set trans.flow off
If you want your selections to be the default settings next time the phone resets, enter this command at the CMD prompt:
CMD: copy active to p1
When your device is properly configured, you can connect to the gateway by dialing in to the appropriate number:
| Modem Speed | Number | Modem Type |
|---|---|---|
| 2400 and lower | 258-7000 | V.22bis, 212A, 103/113 |
| 9600 | 258-7096 | V.32 |
| 14400 | 258-7096 | V.32bis |
| 19200 (on-campus only) | 700-7000 | ISDN |
Note: The normal dialup pool does not support speeds above 14400. Tether, the pay dialup PPP service, supports up to 28800.
(Note: If you have call-waiting service installed on your analog phone, you should disable this service during a dialup session or run the risk of being disconnected if someone calls you. In some cases, you can disable the service for the duration of a call by prefixing the special code *70 before the phone number; for example, you might want to include it as part of your modem's dialup command. Check with your phone company about how to temporarily disable call-waiting for your own phone.)
The phone numbers listed connect you to a CPT (Cisco Protocol Translator) gateway. The CPT allows you to make a connection over a network to a machine that accepts remote logins -- in this case, one of the Athena dialup servers. Several CPTs serve dialup users.
When you first connect to the system, the CPT you reach displays its message of the day, then displays its command prompt. For example:
LINGUINE.MIT.EDU>
The exact prompt differs slightly depending on the CPT you reach, but most of the CPT machines at MIT are named after various kinds of pasta. Once you reach the CPT prompt, you are ready to log into a dialup server.
To log into an Athena dialup server from a CPT, enter one of the names shown in this table:
| Name ... | Connects You To ... |
|---|---|
| athena | any available Athena dialup server |
| athena-express | quick dialup service for brief logins (maximum 15 minute connect time at peak server load periods; see below) |
| athena-x | a server that lets you run X window applications |
(You may type short names for the special servers, express or x. You do not need to include athena-.)
For example:
LINGUINE.MIT.EDU> athena Trying ATHENA.DIALUP.MIT.EDU (18.184.0.31)... Open
connects you to a machine and presents the machine's usual login interface (banner), as in:
ULTRIX V4.2A (primavera) login:
Now you log into the server as you normally would, entering your Athena username and password.
Note: Most of the Athena dialup servers are named after hacks (NO-KNIFE, BIOHAZARD-CAFE, CATHEDRAL_SEVEN, etc.).
Athena currently provides nine SUN dialup servers. Each server is capable of handling multiple users. For dialup servers, the name you specify at the CPT prompt is not a machine name -- it is a name used to connect you to the least loaded server of the kind you want. For example, if you want to log into an express dialup server, identify athena-express as the host at the CPT prompt, and the system connects you to the express dialup server with the lightest load at the time you connect.
You may not necessarily get connected to the same server twice in a row, even if you specify the same general type. (You can tell whether you are logged into the same server by looking at the banner presented when you login or by entering the hostname command.) Similarly, because there are multiple CPT devices, you may not necessarily be connected to the same CPT from one dialup call to the next. In fact it doesn't matter; your session doesn't depend on using the same server or CPT device.
RECONNECTING TO A PARTICULAR SERVER. If for some reason you lose a connection in the middle of your work, and need to reconnect to the same dialup server (to retrieve an autosave file), then at the 'pasta' prompt, type in the name of the server you were working on (e.g., biohazard-cafe) if you remember or have made a note of the name when it appeared in the banner.
When you try to connect to a particular dialup server that is not available, the system "times out" (i.e., returns you to the CPT prompt) after about 60 seconds.
ONCE YOU LOG IN. When you login, the dialup server you connect to asks what terminal type you are using. VT100 emulation is offered as the default; to accept it, press Return or Enter at the prompt. Make sure you enter the correct name for the emulator you are using, since the server uses this information to make your session as efficient as possible.
When you dial up at a slower speed and indicate the speed to the dialup server, emacs and rn try to optimize the way they update your screen. You can indicate the speed interactively, before starting the programs, by typing a command such as the following at the athena% prompt or by putting it in your ~/.startup.tty file:
stty 2400
Remember that, although the dialup servers have a large amount of memory, many users may be logged into a given machine at once. Therefore, if you want to run large or computation-intensive programs, you should do this work on a single-user Athena workstation instead.
This service offers improved performance for brief remote Athena logins, especially to read or send mail. The Dialup Express servers are like the other Athena dialup servers, except that the machines in the Express pool limit the number of users on each machine. When the service is in high demand users are forced off the server after 15 minutes.
Dialup Express does automatic logouts only when the number of users on a machine is above a threshold -- currently set at 10 users. When that threshold is reached, and you have been logged on 15 minutes or more, you will the get the following initial warning message (complete with beeps, if your local machine supports them):
------------------------------------- IN 5 MINUTES YOU WILL BE LOGGED OUT -------------------------------------
You get a second message when there is one minute remaining, and a final message immediately before being logged out.
When you are finished with your Athena session, use the logout command to logout:
athena% logout
Note: If the system displays the message "There are stopped jobs" and does not log you out, it means that an application or program was suspended (usually with Ctrl-z) and not properly terminated. To kill any suspended jobs and be logged out, type logout again at the athena% prompt.
This logs you out from the Athena dialup server, but you are still connected to the CPT. You may select a new host machine, or exit the system completely by entering exit, quit, or q at the CPT prompt:
LINGUINE.MIT.EDU> exit
Alternatively, you can just hang up at the CPT prompt, and the system disconnects you cleanly.
If you hang up during your Athena session, or if your phone line is disconnected, you are automatically logged out from the Athena dialup server and from the CPT.
Every time you log in, Athena checks to see whether your display device can handle X-based windowgrams. When you are connected to Athena via dialup from a terminal, the system cannot start an X-oriented Zephyr client. However, it can send zephyrgrams as text messages. Text messages can be annoying since they get in the way of other text on your screen. The advantage, however, is that you will get filsrv messages that notify you if your file server is going down.
By default, the system does not start up a text-oriented Zephyr client unless you have specifically requested it. Select one of the following two ways to do this:
Set Fallback Variable to TRUE. You can set the fallback variable to true in the file ~/.zephyr.vars. When you set the variable this way, Zephyr displays messages from other users as regular text on your screen during future dialup sessions, but continues to use regular windowgrams for non-dialup sessions. At your athena% prompt enter:
athena% zctl set fallback true
Once you have set the fallback variable to true, you never need to do it again.
Start Up a Terminal-Oriented Zephyr Client. If you have not set the fallback variable to true, the system prints out a warning message indicating that it is not starting up a Zephyr client. In this case, you can start up a terminal-oriented Zephyr client for that session by entering:
athena% zwgc -ttymode
When you have read the message and want to clear your screen, enter clear at the athena% prompt. This leaves you with only an athena% prompt at the top of your screen. Some programs let you redraw the screen. If you are in Emacs, enter Ctrl-l (that's a lowercase "L"). For another program, check the documentation that comes with it.
Zephyr on Athena (AC-34) contains general information about Zephyr. The document is available in the Copy Tech Center in 11-004.
| Parameter | Setting |
|---|---|
| Data Bits | 8 data bits |
| Stop Bits | 1 stop bit |
| Parity | no parity |
| Duplex | full duplex |
| Modem Speed | Number | Modem Type |
|---|---|---|
| 2400 and lower | 258-7000 | V.22bis, 212A, 103/113 |
| 9600 | 258-7096 | V.32 |
| 14400 | 258-7096 | V.32bis |
| 19200 (on-campus only) | 700-7000 | ISDN |
| Name ... | Connects You To ... |
|---|---|
| athena | any available Athena dialup server |
| athena-express | quick dialup service for brief logins (maximum 15 minute connect time at peak server load periods; see below) |
| athena-x | a server that lets you run X window applications |
| Topic | Assistance |
|---|---|
| General questions (try here first) |
Athena Consultants phone: x3-4435 command: olc |
| CPT gateway | Information Systems email: bug-cpt@MIT.EDU |
| Athena Dialup Service | Information Systems email: bug-dialup@MIT |
|
Comments and feedback to olh-suggest@mit.edu
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