TEL-FAQ
PC Telnet FAQ
NCSA Telent Frequently Asked Questions
NCSA Telnet for DOS development and technical support has been discontinued
effective Feb. 1, 1995. Funding for this application is no longer available
and overall interest in DOS applications is deminishing. We recognize there
is still some interest in NCSA Telnet for DOS and the application will
remain on our anonymous ftp server. Enclosed is a list of frequently asked
questions which will help NCSA DOS Telnet users solve the common problems
encountered with Telnet.
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What are the system requirements for Telnet?
A iX286 running a minimum of DOS 2.0 or later using a packet driver for
the Network adapter or modem.
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How do I unzip the file?
Files on our server are compressed using the Shareware utility Pkzip,
version 2.04g. To decompress the Telnet file you'll need version 2.04g
If you need to obtain a copy of this software you can find a copy of
the PKware "Shareware" utilities on our anonymous ftp server. The file
pkz204g.exe can be found in the /PC/Windows/Contrib directory. This
file is a self-extracting executable. If you are not familiar with this
file type, follow the below directions.
o Create a directory c:\util
o Move pkz204g.exe into c:\util
o Change directories to c:\util
o Type pkz204g at the DOS prompt and the file will decompress.
o Read the Readme.doc file
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Where do I obtain documentation for NCSA Telnet?
There are three versions of the NCSA Telnet documents available from
the /Telnet/DOS/docs directory on our ftp server (ftp.ncsa.uiuc.edu).
tel23asc.zip
ASCII version compressed with the PKzip utility.
pctelnet2.3.asc.tar.Z
An ASCII version compressed and archived using UNIX compress and
tar.
telnet2.3.msw.sit.hqx
A Microsoft Word version Stuffed and Binhexed.
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What are packet drivers?
A packet driver is program that allows Telnet to send and receive data
packets through a network adapter or communications card. For example,
the 3Com509 card is one such network adapter or comm card.
NCSA Telnet offers internal support for "some" of the many
communications cards that are in use. The cards that Telnet supports
directly are:
o 3Com501, 3Com503, 3Com523
o Western Digital WD8003A, WD8003E, WD8003EB
o AT&T starlan 10
o Ungermann-Bass PC-NIC, Ungermann-Bass NICps/2
o Micom NI5210
Most of these cards were built during the Stone Age (1988-1991'ish) and
are probably associated with the iX286 and early iX386 systems. Due to
the increasing number of cards that came to market and the creation of
the Packet Driver Specification (PDS) developed by FTP Software, we got
out of driver development. If you have a card other than the few
mentioned above, you will need to download a packet driver. These
drivers are freely available at the anonymous ftp site oak.oakland.edu
in the /SimTel/msdos/pktdrvr directory.
Drivers and technical assistance are also available through Crynwr
Software. For details about the services offered by Crynwr Software
please contact them directly.
Crynwr Software (info@crynwr.com)
11 Grant St.
Potsdam, NY 13676
315-268-1925 (-9201 FAX)
Crynwr also has information available from the World Wide Web. If you
have access to a WWW Browser such as NCSA Mosaic, check out the
following URL. http://www.crynwr.com/crynwr/home.html
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How do I use packet drivers?
To use a packet driver with NCSA Telnet, you would install the driver
according to its instructions. Next edit your config.tel file to
reflect the following information:
1. Ensure all other hardware= options are commented out. To comment
out a line in you config.tel place the pound symbol, #, at the
beginning of the line.
2. Add or Edit these lines:
+ hardware=packet
+ ioaddr=[software interrupt of the driver]
For example if you load the packet driver using 0x60 for the software
interrupt, the entry would read:
o hardware=packet
o ioaddr=60
For more information about which software interupt to select, see the
installation instruction of your packet driver for the default setting.
If you still cannot determine the software interrupt, most drivers
provide help if you attempt to invoke the driver without any options or
with the /help or /? switch. For example, if you use the 3c509 driver,
cd to the directory that contains the driver and enter the following
command at the DOS prompt:
3c509 or
3c509 /help or
3c509 /?
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How do I run Telnet with a Novell network?
NCSA doesn't use a Novell LAN. However, one of our users wrote:
There is a packet driver that sits on top of the ODI interface called
odipkt. odipkt.com is available from hsdndev.harvard.edu
(128.103.202.40) in /pub/odipkt.
There is a sample net.cfg file in that dir. A note should be made that
the order of the envelope statements is the order that they are
assigned. (I found the order backwards from the doc).
load:
lsl (odi driver from vendor or from wsgen disk odi dir)
odipkt 1 (If envelope for ethernet_ii is the second one in the
net.cfg file, odipkt 0 otherwise)
ipxodi
netx
Now telnet and ftp work fine while connected to the novell network.
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Will Telnet run in Windows?
NCSA's PC Telnet was not designed to be run in MS Windows. Some users
have reported success when they increase the size of memory available
in the PIF file....others have not gotten it to work at all. You must
also check the background option when you load Telnet.
If you are looking for a native Windows telnet application, try WinQVT.
This application is a "Shareware" program that offers Telnet, FTP,
News, Mail and LPR utilities. You can find the latest copy of this
program at the anonymous ftp site oak.oakland.edu in the
/pub/win3/winsock directory. We also keep a copy of this file on our
anonymous ftp server. You can find qvtws398.zip in the
/PC/Windows/Contrib directory of ftp.ncsa.uiuc.edu.
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Does Telnet support TN3270 teminal emulation?
NCSA's PC Telnet does not support TN3270. However, Clarkson University
has modified our source code to support the TN3270 and they have
released it as CUTCP. For more information about the latest release of
CUTCP, see the readme file available from the anonymous ftp server
omnigate.clarkson.edu. You can find the file in the /pub/cutcp
directory.
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Can I obtain and modify the source code?
NCSA's PC Telnet source code is in the public domain and you are
welcome to modify and redistribute it. To obtain a copy of the source
code, download tel2308s.zip from the /Telnet/DOS directory of our
anonymous ftp server. The source code was developed using Microsoft's
C/C++, version 7.0 and MASM 5.0.
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Can I use Telnet over a serial connection (modem)?
Yes, you can find a number of slip drivers and dialers available from
the /SimTel/msdos/pktdrvr directory of the anonymous ftp site
oak.oakland.edu. Select a SLIP packet drive from the 00_index.txt file.
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Can I use Telnet with AppleTalk?
Using an Appletalk network involves some special considerations. First,
you must load the Appletalk driver into memory. Version 1.0 of the
"ATALK.EXE" driver was used in the development of NCSA Telnet.
The second consideration involves the "interrupt=" line. The
"interrupt=" line in your CONFIG.TEL file refers to the software
interrupt the Appletalk driver is using, not the hardware interrupt the
card is set to. For example, if your Appletalk card is set to IRQ2, you
should NOT set the "interrupt=" line to "2". Instead, the value should
be set to the software interrupt, usually "interrupt=60" or
"interrupt=5C".
Static addressing does not work at the current time in NCSA Telnet 2.3
using the AppleTalk driver. Therefore, NCSA Telnet ignores any IP
address you set in your CONFIG.TEL file, and assigns an IP address to
your PC by the Appletalk gateway.
Some AppleTalk users have been more successful with v2.3.03 of Telnet.
If you would like to try v2.3.03, it's available on our anonymous ftp
server in the /Telnet/DOS/contributions directory.
One of our users wrote:
To load telnet from the dosprompt [nothing telnet-specific in
config.sys or autoexec.bat we use the following sequence:
lsl.com
ltalk.com
atalk.com
ashare.com
compat.com
d:\network\telnet\telbin -n -h d:\network\telnet\config.tel
where all of the atalk stuff would be in the current directory and all
of the telnet stuff is in d:\network\telnet.
broadcast=255.255.255.255
netmask=255.255.255.0
hardware=atalk # network adapter board (Appletalk)
interrupt=60 # I have an Apple or Farralon card and PhoneNET Talk #
remember to run COMPAT.COM for NCSA to run on # LocalTalk
#interrupt=5C # I have a TOPS Flashcard
mtu=512 # maximum transmit unit in bytes
maxseg=512 # largest segment we can receive
rwin=512 # most bytes we can receive without ACK
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What do I do when Telnet is running out of memory?
The latest version of Telnet takes around 400k to run. If you have memory
problems, reduce or comment out the number of lines that set the scrollback
buffer in the the config.tel file. For example:
scrollback=100 # number of lines of scrollback per session # Default is
(0)
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How do I scroll back the screen?
You can scroll in one line increments using the scroll lock. Press the
scroll lock in and use the arrow keys to increment by one line. To turn
off this feature, just turn off the scroll lock.
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How do I remap keys?
When remapping keys refer to Appendix E of the 2.3 docs. There is also
information in chapter 7, Installation and Configuration, page 7.8 and
the sample config.tel file we provide with Telnet.
From Chapter 7:
keyfile=filename "specifies an additional keyboard mapping file to
provide move key definitions. This file over-rides the definitions
in the telnet.key file."
From the config.tel file:
#keyfile=keymap.key #pathname of your keyboard re-mapping file.
Re-mapping will over-ride the default telnet.key file and you will have
to include all keys in this new file. You can easily do this by copying
the contents of the telnet.key file into the newfile and then add the
key remap information.
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Can you explain rwin, mss, and mtu in the config.tel file?
Rwin is the TCP sliding window. The window allows transfers to proceed
without waiting for an acknowldgement for every packet, but rather
transmitting (up to) a window of data before waiting for
acknowlegments. If the window size equals the mss, then there is no
window, because every packet must be acknowledged. If large windows are
selected and data is lost, the entire window may have to be resent,
hence the warning that larger is not always better. During a transfer,
both sides of the connection continually advertise what their free
space in the window is, so that the transfer side can control data flow
to only send what the receiving side can accept.
Mss is the maximum segment size that the TCP connection advertises to
the other side. The other side then sends packets up to this size. In
FTP, all of the data packets except the last will probably be this big.
Mtu is the maximum size of outgoing packets on the TCP connection. When
transmitting FTP data to a host, packets will be this big, unless the
host advertizes a smaller mss. For Telnet and the FTP control
connection, packets are sent per character, so this is never an issue.
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Can I capture what I see into a file or send it to the printer?
Text that appears on the screen can be captured and sent to a file or
the local printer. When you press Alt-C capture is turned on. Pressing
Alt-C again turns capture off. Any text that appears on the screen is
captured and appended to the capture file. NCSA Telnet never erases the
capture file, only appends to it. The default capture file is
"capfile", but this may be changed by using the Parameter menu (Alt-P).
Changing the capture filename to prn will send all captured text to a
local printer.
Note: you can capture text to a file or the printer in any session, but
not for more than one session at a time. When capture is active for a
session in the background, you cannot invoke capture in the current
session.
If you press Alt-D, NCSA Telnet dumps the contents of the current
session screen into the capture file.
****You cannot paste from the capture file into a Telnet session****
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How do the cut and paste features of NCSA Telnet work?
The cut and paste functions allow you to copy blocks of text from one
session to another, or within the same session. To use these functions,
follow these steps:
1. Enter Scrollback mode via Scrl_Lock or the right mouse button.
2. Move the cursor to the beginning position of the text you wish to
copy, and press the space bar.
3. Move the cursor to the end of the text and press the space bar
again. This action selects the area to copy.
4. Press ALT-C while still in scrollback mode. This action copies the
text into a buffer.
5. Exit Scrollback mode, and switch sessions by pressing ALT-N or
ALT-B, if you desire.
6. Position the cursor where you wish to insert the text, and press
ALT-V. This action inserts the text at the current position as if
you had typed it in.
You can use the copy and paste functions without touching the keyboard
if you have a Microsoft-compatible mouse attached and driver loaded.
1. Press the right mouse button to enter Scrollback mode.
2. Scroll to the beginning of the text you wish to copy, and press
the left mouse button.
3. Move the cursor to the end of the text, and press the left mouse
button again.
4. Press and hold the left mouse button, press the right mouse
button, then release both buttons. This action copies the text
into the buffer.
5. Exit Scrollback mode by pressing the right mouse button.
To paste the buffer to the screen, press and hold the right mouse
button, then press the left mouse button, then release them both. The
text should appear as if you typed it in.
Note: You cannot paste from the capture file. The capture file and
scrollback buffer are NOT the same.
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Can I FTP or rcp to my PC from a remote site?
Yes, if you are using Telnet's server mode. Invoking telnet with the -s
option enters the server mode. In this mode, you can establish remote
connections as usual with telnet, except that telnet stays active even
when all remote sessions have been closed. The reason for this is that
when in server mode Telnet waits for external FTP and rcp requests.
This allows you to leave your PC and access files there from a remote
location.
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Can I restrict access to my machine when in server mode?
If you want to restrict access to your machine when in server mode, you
will need to run telpass and create a password file. Start up Telpass
from DOS with the name of the password file that you wish to edit.
Example C:\telpass pwfile
Follow the instructions in Telpass to create/edit the password file.
Once you have a password file, you must add a passfile option to your
config.tel file so that Telnet knows where to find the password file.
You must include the full path to the password file.
Example passfile="c:\bat\ftppass"
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Can I permanently change my screen colors?
You can make color changes permanent for particular sessions. To do so,
simply add the options below to the host information contained in the
config.tel file.
nfcolor=white (normal forground)
nbcolor=black (normal background)
rfcolor=black (reverse forground)
rbcolor=white (reverse background)
ufcolor=blue (underline forground)
ubcolor=black (underline background)
Put these options after the keyword name, to associate colors to the
named session. The parameters are installed whenever a connection is
opened with that session name.
For machines with EGA or better graphics adapters, the following colors
are also available:
BLACK, BLUE, GREEN, CYAN, RED, MAGENTA, YELLOW, WHITE
These colors are in all caps, and for the forground colors they are the
highlighted version of the lowercase colors. For background colors,
they make the foreground blink.
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What does the Local host or gateway not responding error mean?
The possible reasons for this message are:
1. Network problem
2. Configuration file problem
3. Host is down
4. Gateway is down
The possible solutions to this problem are:
1. Check to see that the network is up and running
2. If the computer is not on your local network, check to see if the
gateway is up and running.
3. Ask the system administrator to check the specification of the
gateway (gateway=) in your configuration file.
4. Check the IP number of the computer you are trying to connect to.
5. Check to make sure that your computer is attached to the network.
6. Check the integrity of the network cable.
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Why can't I get BOOTP working on the latest version of telnet?
We have heard reports that BOOTP may still be broken, so that some
systems cannot use it. If you are having problems, you may want to try
2.3.03 instead. This version is available via our ftp site in the
/Telnet/DOS/contributions directory.
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National Center for Supercomputing Applications
University of Illinois at Urbana/Champaign