NCSA Telnet for the PC Version 2.2 July 1988 (ASCII printable version of this document) UD-99 US-14 NCSA Telnet Version 2.2 source code and documentation are in the public domain. Specifically, we give to the public domain all rights for future licensing of the source code, all resale rights, and all publishing rights. We ask, but do not require, that the following message be included in all derived works: Portions developed by the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign. PROBLEM REPORTS Mail all suggestions and manual corrections to: NCSA Documentation and Publications Department 152 Computing Applications Building 605 E. Springfield Ave. Champaign, Illinois 61820 DISCLAIMER THE UNIVERSITY OF ILLINOIS GIVES NO WARRANTY, EXPRESS OR IMPLIED, FOR THE SOFTWARE AND/OR DOCUMENTATION PROVIDED, INCLUDING, WITHOUT LIMITATION, WARRANTY OF MERCHANTABILITY AND WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE. TRADEMARK ACKNOWLEDGMENTS PostScript is a registered trademark of Adobe Systems Inc. UNIX is a registered trademark of AT&T. SideKick is a registered trademark of Borland International Inc. VAX, VMS, and VT102 are registered trademarks of Digital Equipment Corporation. Hercules is a trademark of Hercules Computer Technology. Enhanced Graphics Adapter, IBM PC, PC/AT, PC-DOS, Personal System/2, and Topview are registered trademarks of International Business Machines Corporation. Microsoft Windows and MS-DOS are registered trademarks of Microsoft Corporation. Revolution 512 is a trademark of Number Nine Computer. Tektronix 4010 and Tektronix 4014 are trademarks of Tektronix Corporation. NIC is a trademark of Ungermann-Bass. EtherCard PLUS is a trademark of Western Digital Corporation. Ethernet is a trademark of Xerox Corporation. 3COM and Etherlink are trademarks of 3COM Corporation. INTRODUCTION PURPOSE OF NCSA TELNET NCSA Telnet Version 2.2 for the PC provides interactive access from an IBM PC or compatible to telnet hosts on TCP/IP networks. NCSA Telnet is an implementation of DARPA standard telnet with added features that take advantage of the local processing power of the PC. SPECIAL FEATURES Special features of NCSA Telnet for the PC include: % VT102 emulation % Simultaneous logon to a number of computers % Ability to capture text to the PC disk or printer % File transfer server (standard FTP) % Remote copy server (rcp) for use with UNIX hosts % Ability to take full advantage of PC colors % Topview/Windows compatible mode % Tektronix 4014 emulation % Domain name lookup % Optional use of RARP for determining PC's IP address % Scrollback SYSTEM REQUIREMENTS To use NCSA Telnet you must have the following hardware: % IBM PC, PC/XT, PC/AT, IBM PS/2 model 30, or "true" compatible computer with one of the following Ethernet adapter boards: 3COM 3C501 Etherlink MICOM NI5210 Ungermann-Bass PC-NIC (same as IBM Baseband Adapter) Western Digital WD8003E EtherCard PLUS % or IBM PS/2 models 50,60 or 80, or "true" compatible computer with one of the following Ethernet adapter boards: Ungermann-Bass NICps/2 3COM 3C523 Etherlink/MC % 384K minimum memory % Ethernet or Thin Ethernet to connect the PC and other computers To use NCSA Telnet you must have the following software: % PC-DOS or MS-DOS Version 2.0 or later. % A standard text editor will be helpful when editing the configuration file. ABOUT THIS MANUAL This section describes the organization of this manual, and the conventions and nomenclature used in developing it. Organization of This Manual This manual is organized into six chapters. Each page of each chapter is given a unique number that consists of the chapter number, a period, and the number of that individual page (beginning with the first page of the chapter). For example, page 2.3 is the third page of the second chapter. Each chapter is divided into sections, and most sections are divided into subsections. Manual Contents This manual is organized into the following chapters: Chapter 1, "Starting and Quitting NCSA Telnet," describes how to start NCSA Telnet and how to open and close a connection between your PC and one remote host. Chapter 2, "Introduction to Managing Sessions," introduces NCSA Telnet's capability for multiple connections. It also discusses standard VT102 key emulation, keys used for common EDT operations, and using a capture file. Chapter 3, "More about Managing Sessions," discusses multiple sessions in detail. The Parameters menu options, DOS shell feature, and several advanced functions are also described. Chapter 4, "File Transfer," outlines procedures for transferring files between a PC and a telnet host. Chapter 5, "Tektronix 4014 Emulation," discusses NCSA Telnet's ability to emulate a Tektronix 4014 graphics terminal. Chapter 6, "Installation and Configuration," contains information for system administrators (and other experienced users) to use when installing and customizing a system. Appendix A, "Error Conditions," describes some of NCSA Telnet's error messages, as well as their causes and solutions. Appendix B, "NCSA Telnet Command Reference," lists commands available from the PC keyboard. Appendix C, "Configuration File Summary," lists the keywords for configuration file parameters. Notational Conventions in This Manual Figure I.1 shows some typical screen/user interactions using the conventions employed in this manual. Those conventions, and others, are explained here. C:\> telnet machinename [machinename...] National Center for Supercomputing Applications NCSA Telnet for the PC version 2.2 (c) Copyright 1987,1988 Board of Trustees of the University of Illinois ALT-H presents a summary of special keys 4.2 BSD UNIX (newton) login: Figure I.1. Example of Notational Conventions dothis Information shown in courier boldface type represents user entries. ALT-key Press and hold the ALT key and then press the key designated by key. Then release both keys at the same time. variable Do not enter the actual characters shown. Command line characters shown in lowercase courier bold italic type represent an entry that may consist of different characters every time you make the entry. In other words, it is a variable entry. If it indicates a machine response, it means the actual wording of the response will vary, depending on the filename, machinename, and so on. ... Do not enter an ellipsis. The ellipsis indicates that you may enter more material similar to the material preceding the ellipsis. [ ] Do not enter square brackets. Material or actions presented between square brackets is optional and should be entered only in certain cases. INSTALLATION NOTE This manual assumes that NCSA Telnet has been installed on your system by a system or network administrator who has assigned an IP address to your PC. Chapter 6 contains information to be used by system administrators and other experienced users to install and customize NCSA Telnet. CHAPTER 1 STARTING AND QUITTING NCSA TELNET CHAPTER OVERVIEW This chapter describes how to start NCSA Telnet and how to open and close a connection between your PC and one remote host. NCSA Telnet also features multiple-session capabilities. If you want to use more than one login session simultaneously, see Chapter 2, "Introduction to Managing Sessions." Also see Chapter 2 for information on how NCSA Telnet emulates a VT102 keyboard. STARTING THE PROGRAM To run NCSA Telnet from the PC command line, from any subdirectory, enter: C:\ > telnet machinename This initiates a connection to the remote computer with the name given as the machinename parameter. Normally the host machine immediately prompts you for a login name and password to begin the session. Setting the Terminal Type NCSA Telnet emulates a VT102 terminal. When you log in to a host, the host operating system does not know what type of terminal you are using. Consult the operating system manual for how to set terminal type and try setting it to VT100 or VT102. For systems that do not support VT102 (such as many UNIX systems), use VT100, which is compatible with VT102 emulators. These examples show how to set the terminal type for two popular operating systems, UNIX (using the C shell) and VAX/VMS. newton% set term=vt100;tset For UNIX hosts. B$ SET TERM/INQ For VAX/VMS hosts. THE HELP SCREEN For a command summary, press ALT-H. A one-screen summary of command keys appears, as shown in Figure 1.1. The online help summary serves as your quick reference to the command keys. Keyboard usage for NCSA telnet: Alt-A add a session Alt-Y Interrupt Process Alt-N next session Alt-O Abort Output Alt-M message screen Alt-Q Are you there? Alt-E escape to DOS shell Alt-U Erase line Alt-G graphics menu Alt-K Erase Kharacter Alt-C toggle capture on/off Alt-X close connection Alt-R reset VT102 screen HOME exit graphics mode Alt-H this help screen Ctrl-HOME clear/enter graphics mode ScrLock pause/restart screen (DO NOT use Ctrl-NumLock) ScrLock enter/exit scroll-back mode Alt-T start file transfer as if typed: ftp [internet address] Alt-I send my internet address to host as if typed Alt-S skip scrolling, jump ahead Alt-P change a parameter, one of: color, capture file name, backspace, session name, screen mode Alt-F3 abort program completely. STRONGLY discouraged Press ESC for information page, space bar to return to session: Figure 1.1. NCSA Telnet Help Screen QUITTING NCSA TELNET To exit the program, log out of the host machine using the appropriate logout procedure for that machine. If you have concurrent sessions with more than one machine, you must log out of each machine. Then NCSA Telnet exits and the DOS prompt is displayed. If one of the hosts crashes, or a session is otherwise hung up, press ALT-X. NCSA Telnet will first prompt you for confirmation and then attempt to close the session while preserving your other live sessions. When all else fails, and it appears that all of the connections are completely jammed, press ALT-F3 to abort the program. Only use ALT-F3 as a last resort. CTRL-C Will Not Exit Pressing CTRL-C or CTRL-BREAK will send a CTRL-C to the host. These commands cannot be used to break out of NCSA Telnet, and they will not end your session. CHAPTER 2 INTRODUCTION TO MANAGING SESSIONS CHAPTER OVERVIEW This chapter introduces NCSA Telnet's capability for multiple connections with one or more hosts. The chapter describes standard VT102 key emulation, keys for some common EDT operations, how to work with multiple sessions, and operations with the capture file. KEYBOARD USAGE When NCSA Telnet is running, the PC appears to the host as a VT102 terminal. For keys that the PC keyboard and the VT102 keyboard have in common, NCSA Telnet transmits the keystrokes unmodified. The VT102 keyboard has some keys that the PC keyboard does not have, and treats other keys differently. Many VT102 keys have special meanings when they are transferred to the host. To provide full VT102 functionality, some PC keys are used to emulate the operation of VT102 keys. Table 2.1 lists the PC keys to use for VT102 terminal emulation. Table 2.1. PC Keys Used for VT102 Terminal Emulation To Send a VT102 Code Press PC Key(s) RETURN ENTER DELETE BACKSPACE BACKSPACE CTRL-BACKSPACE LINE FEED CTRL-ENTER Keypad ENTER F10 (not identical to RETURN) Keypad . (decimal point) DEL Keypad - (hyphen) F5 Keypad , (comma) F6 Keypad 0 INS Keypad 0 to 9 ALT-0 to ALT-9 -, /, ,, . -, /, ,, . PF1 to PF4 F1 to F4 See Chapter 3 and Chapter 6 for information on how to switch the designations of these keys. VT102 Functions for the EDT Editor Table 2.2 lists some VT102 terminal emulation functions that help users who are working with the EDT editor under VAX/VMS. WARNING: If you are not using the EDT editor, ignore the use of these keys. They produce unpredictable results on other systems. Table 2.2. VT102 Functions for the EDT Editor For the EDT Operation Press PC Key(s) Save-and-exit F9 Select F7 Cut F8 Paste F1,then F8 Cursor to beginning of this line HOME Cursor to end of this line END Scroll backward one screen PG UP Scroll forward one screen PG DN Return to the previous formfeed CTRL-PG UP Go to the next formfeed CTRL-PG DN EDT help screen F2 MULTIPLE SESSIONS When you first run NCSA Telnet, you can start up multiple sessions with a single command. C:\> telnet machinename [machinename ...] Even if you do not choose multiple sessions when you first run NCSA Telnet, you can later add sessions, as described in the following paragraph. Using ALT-A to Open Another Session When you have opened a connection to a single host, you can open a second connection, to that host or a different one. To do this, press ALT-A (A for add). NCSA Telnet responds by prompting for the name of a computer to which it should attempt a connection. Indicating the Host NCSA Telnet can only communicate with host computers that have IP addresses. IP addresses can be looked up several different ways. 1. Any name that is in the configuration file can be used. (Your system administrator can tell you the names listed there.) 2. NCSA Telnet can be configured (by the system administrator) to use the domain-based nameserver to look up host names. Any name that can be resolved by the domain nameserver can be used. An example is sri-nic.arpa. 3. You can use the full Internet number of the machine, in decimal, separated by periods, such as 192.17.22.20. 4. If the machine is on the same Ethernet, you can enter a pound sign (#), followed by the host number it uses on your Ethernet. The host number is determined by the class of addressing and the subnet mask (which your system administrator can determine for you). For example, if your PC is host 192.17.22.20, you can access host 192.17.22.30 by entering #30 for the host address. Response Time of the Host NCSA Telnet attempts to make a login connection with the named host. Usually the connection is instantaneous, and the host machine prompts you for a login name immediately. However, the connection attempt may take several seconds. Even after the telnet connection has been completed, if a remote host is heavily loaded it may take additional time (up to two minutes) to prompt you for a login name. When the connection is established, the asterisk (*) in the status box for the connection will disappear or change to a small box. If NCSA Telnet makes the connection, but the remote host does not let you log in, you may want to press ALT-X to end the connection. Using Scrollback Mode The SCROLL LOCK key does double duty. It prevents the screen from scrolling when new text arrives, and also puts you into scrollback mode. In scrollback mode, the up and down arrow keys and PG UP and PG DN scroll the screen backwards and forwards. When you press the SCROLL LOCK key again, it ends scrollback mode and resets the working area of the screen. The number of lines that are saved is limited by the amount of memory in your machine and is set in the configuration file. If your PC runs out of memory, or the specified number of lines have already been stored, it will start wrapping the scrollback around. NOTE: No other commands work while you are using scrollback mode. The Status Line Only 24 lines are needed for VT102 terminal emulation, so line 25 on your PC screen is used to indicate the connection status of your terminal sessions. For each host you are connected to, a session name appears in reverse video. The name in the lower left corner of the screen is the current session. Beside each name is a status box that indicates various attributes of a session: (gray) Connection is established, waiting (small box) Active connection, always in lower left corner * Connection pending, trying to connect to host / or \ Text has been written to this invisible session Switching Between Sessions (ALT-N) The status line at the bottom of the screen indicates the active telnet sessions. To rotate to the next session, press ALT-N (for next). This action makes the next session the current one and moves its name to the lower left corner of the screen. The screen image for this session is now displayed, and you should be ready to proceed. Characters typed at the keyboard are always sent to the current session. Displaying Console Messages (ALT-M) In the process of connecting and communicating with other hosts via TCP/IP, NCSA Telnet provides you with information on the console (message) screen. To see this screen, press ALT-M. When you have viewed the messages, press any key to return to your session. The information on the console screen can tell you about errors, warnings, FTP access to your PC, and network conditions that may be of concern to network administrators. Exiting the Present Connection (ALT-X) ALT-X initiates the close procedure for the current session. To prevent this from happening accidentally, NCSA Telnet prompts you to confirm that the connection should be closed. After confirmation, the connection shuts down. The close may take several seconds to complete. NOTE: You can press ALT-X to log out of a host as well as terminate a given session, but it bypasses normal conventions and may cause problems for the host. The correct way to close a connection with a host is to log out of the host using the normal logout procedure for that host. CAPTURE FILE OPERATIONS 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 text to it. The default capture file is named capfile, but you can change that, as discussed next. Designating a Capture File Designate a different capture file by using the Parameter menu. When you press ALT-P the Parameter menu is displayed. (Most of the Parameter menu choices are discussed in Chapter 3.) Use the arrow keys to select the Parameter menu entry for the capture file name. Press RETURN to clear the current entry and then enter your new file name. After the name of the capture file has been changed, all subsequent ALT-C commands use the new capture file. You can also change the name of the capture file "permanently" in the configuration file (see Chapter 6). Using PRN If you want to send all captured text directly to a local printer, use the filename prn as the designated capture file name. PC-DOS reserves this filename for the printer. A common problem can occur while you are capturing files to the printer that can cause NCSA Telnet to abort. If the printer is offline or out of paper when a capture begins, the message: Error, A(bort) R(etry) or I(gnore)? appears on the screen. At this point, turn on the printer and then press R for retry. Do not press A at this point because it will abort NCSA Telnet and cut off all of your network connections. One Capture at a Time You can capture text to a file or the printer in any session, but not for more than one session at a time. When a capture is active for a session in the background, you cannot invoke capture on the current session. If you attempt to do so, you will not get the confirmation message on line 25 and NCSA Telnet reminds you of the error. The capture procedure will continue to capture all text for the background session while you interact with the current session. CHAPTER 3 MORE ABOUT MANAGING SESSIONS CHAPTER OVERVIEW This chapter continues the discussion of multiple sessions and describes more advanced aspects of the NCSA Telnet working environment. The chapter explains how to reset the VT102 screen, how to abort NCSA Telnet, the DOS shell feature, and Parameters menu options. KEYBOARD COMMANDS Skip Command (ALT-S) The skip command causes the screen to "skip ahead" over scrolling text. The text is placed into the scrollback region, but the screen update advances to the end of the local network buffer instead of printing every line on the screen. The purpose of this feature is to help you when you type a command which produces so many lines of output that you don't want to wait for it to scroll by. Press ALT-S and the screen will pause, then redraw at the end of the local buffer. This won't solve all of the network buffering problems for interactive use, but it should help. Capture to disk and scrollback are not affected by skip. Resetting the VT102 Screen (ALT-R) ALT-R clears and resets all modes associated with the current virtual VT102 screen. Some host programs can accidentally set graphics mode on or fail to leave graphics mode. You press ALT-R to override all VT102 mode settings. These include turning off wrap mode, resetting graphics mode, setting the keypad mode back to the default, and resetting tabs to every eight spaces. After using ALT-R, you may wish to set your terminal type again to allow the host to reset whatever VT102 modes it needs. Aborting the Program (ALT-F3) If for some reason none of the current connections respond, SCROLL LOCK is not on, and ALT-R and ALT-X do not appear to have any effect, ALT-F3 is a general abort command that exits NCSA Telnet and returns you to DOS. If NCSA Telnet is aborted with ALT-F3, it cannot notify the host(s) that your session(s) are terminated. Your sessions are left in an undetermined state. This can cause a variety of problems for the host, because it cannot immediately determine that the session has ended. For example, you may have programs which continue to run on the host, even though you exited telnet with ALT-F3. Escape to DOS Shell (ALT-E) Pressing ALT-E to escape to DOS preserves your connections while you use the DOS command shell. You may use most DOS commands and programs, including those which look at directories, edit source files, or even compile programs. To return to NCSA Telnet, you must enter the command exit at the DOS prompt. During the escape to DOS, NCSA Telnet is monitoring the Ethernet for incoming packets every one-half second. If you run other programs which affect the Ethernet or the timer which NCSA Telnet uses, your connections may be lost or worse, your computer may crash. The following programs are examples of those which terminate the network handling of NCSA Telnet, causing connections to be lost or DOS to crash: % SideKick (it turns off timer processes, so it can cause lost connections) % All network programs (they reset the Ethernet board) % NCSA Telnet (it is a network program) % User FTP (it, too, is a network program) % format, the DOS format utility for floppy disks % FileCommand II NOTE: Watch memory usage to prevent crashing. Also, remember to exit when you have finished your DOS activities. PARAMETER MENU Press ALT-P to display the Parameter menu options, which appear on the screen as shown in Figure 3.1. These options control the settings for text color, echo mode, backspace key, session name, terminal type, capture file name, screen mode and file transfer mode. You can change the fields that are shown in bold to different values. ALT-P Parameter menu < Select parameters, F1 to accept, F10 to leave unchanged > --------------- Color setup and session parameters ----------------- Text: normal reverse underline Normal Foreground (nfcolor) - green Normal Background (nbcolor) - black Reverse Foreground (rfcolor) - black Reverse Background (rbcolor) - white Underline Foreground (ufcolor) - blue Underline Background (ubcolor) - black Use remote echo or local echo - Remote echo Backspace key sends - Delete Session name *> ahostname Terminal type - VT102 and Tek4014 -------------- Parameters which apply to all sessions -------------- Capture file name *> capfile Screen mode (for BIOS compatibility) - Direct to screen File transfer is - Enabled Use arrow keys to select, Enter clears changeable field (*>) Figure 3.1. Parameter Menu The up arrow, down arrow, HOME, and END keys allow you to move the cursor from option to option. The left and right arrow keys rotate through the allowed settings for each option. For each field that you wish to change, move the cursor to that field and press the left or right arrow until the desired value appears. After changing all of the fields that you wish to change, press the F1 key to return to your session with the changes in effect. If you make a mistake, or decide that no changes are necessary, press F10 to return to your session without any changes taking place. There are two special fields, marked with the symbol *>, to indicate that the present value may be changed by typing another. To change one of these, place the cursor on top of the changeable field and then press RETURN. The program blanks the field and allows you to enter a new value. Press RETURN when you are finished entering the new value. After you enter a new value, but before you press F1, the old value still remains in memory and you may use the left or right arrow keys to regain the old value. Following are descriptions of the parameters you can set. Screen Text Colors Host programs expect to be able to control the attributes of characters on the VT102 screen. Command codes are sent to your PC to display characters in normal, reverse, underlined, blinking, and bold attributes, or combinations of these. When normal, reverse, and underline text are required, you have control over which colors are used. When blink or bold attributes are required, NCSA Telnet adds them to your selected colors. For normal, reverse, and underlined characters, NCSA Telnet gives you your choice of foreground and background colors, a total of six settings. The color choices for a PC color video display are black, blue, green, cyan, red, magenta, yellow, and white. For each of the text modes, normal, reverse, and underlined, use the Parameter menu to select the foreground and background colors. As you change the selections, the sample text on the fifth line of the screen provides an example of how the text will appear in the VT102 emulation. On monochrome screens, when you display a character in the color blue, the PC produces a visible underline on the screen instead of blue coloring. Color screens do not have the visible underline capability and use a visible blue color instead of underlining. Bold and blinking attributes from the VT102 screen appear as bold and blinking characters on the PC screen. Remote Echo and Local Echo When the response time of the network is long (such as with satellite transmission), you may want to buffer your keyboard input locally, only sending characters to the host when you press RETURN. This is often referred to as a line mode or local echo mode. The alternative to line mode is called character mode or remote echo mode, where the local program immediately sends, and remote host echoes, every character over the network. In local echo mode, most characters typed at the keyboard are buffered by NCSA Telnet until you press RETURN, which sends the characters to the host all in one packet. There are some exceptions to this rule. % CTRL-U erases the local buffer. % Backspace (CTRL-H) erases the most recent character added to the local buffer. % Tab (CTRL-I) forces NCSA Telnet to send the local buffer (with the tab). % All other control characters echo with a caret (e.g. ^A) and force NCSA Telnet to send the local buffer with the control character included. % Arrow keys and all other unprintable ASCII characters, the escape character for example, force NCSA Telnet to send the local buffer, with the character included. % You cannot send a CTRL-U or Backspace to the host in line mode. % ALT keys and other local command keys are not affected by local echo mode. NOTE: For full screen editing, character mode (remote echo) is necessary, so most hosts use this mode. When full screen editing is not required, line mode may be more efficient. Function of the Backspace Key NCSA Telnet automatically translates BACKSPACE keypresses into DELETE codes, for compatibility with systems that prefer the use of DELETE to BACKSPACE. If you find that your backspaces are not being accepted, the host you are connected to may prefer the reverse setting. To test this possibility, use the Parameter menu to change the default translation so the BACKSPACE key functions as backspace. If the result is that your backspaces are accepted, then the host does prefer the BACKSPACE to DELETE. If you require the reverse setting frequently, you or your system administrator may want to permanently reset the backspace function using the configuration file, as described in Chapter 6. Changing the Session Name The status line shows a 14-character session name for each active session. For each session, the machine name that you typed to initiate the session displays as the default. The Parameter menu allows you to change the status line name for the current session. Press RETURN to clear the current entry and type in a new name. Only the first 14 characters are used. Changing the Terminal Type Generally, the default terminal type of VT102 with Tektronix 4014 is acceptable. There may be specific cases where you need to force some restrictions on the way the terminal acts, so you may want to limit the amount of emulation that NCSA Telnet does. The three choices of terminal types are: % VT102 terminal with Tektronix 4014 graphics % VT102 only, graphics commands ignored, but VT102 commands accepted % Dumb terminal, no VT100 codes or Tektronix codes interpreted Changing the Capture Filename The name of the current capture file can be changed on the Parameter menu. Press RETURN to clear the current entry and then enter your new filename. After the name of the capture file has been changed, all subsequent ALT-C commands use the new capture file. You can also change the name of the capture file "permanently" in the configuration file (see Chapter 6). See Chapter 2 for a description of capture file operations. File Transfer Mode The Parameter menu allows you to disable or enable file transfers. When you select Disabled, neither FTP nor rcp is allowed. When you select Enabled, the FTP and rcp servers are restarted. Chapter 4 contains more information on the file transfer methods for NCSA Telnet. The default file transfer modes for FTP and rcp can be set in the configuration file (see Chapter 6). Screen Mode (BIOS Compatibility for Windowing Packages) In the normal, fast mode, writes are made directly to the screen for increased speed, but this mode is incompatible with windowing packages like Topview or Microsoft Windows and may cause snow on some screens. NCSA Telnet has a compatibility mode where IBM's BIOS calls are used for all access to the screen. Usually, the windowing compatibility mode is set up in the configuration file with the bios option. However, if a change is needed once you are in the program, the Parameter menu option is available. CHAPTER 4 FILE TRANSFER CHAPTER OVERVIEW This chapter describes procedures for transferring files between a PC and a network host, using NCSA Telnet's two built-in file transfer servers: FTP and rcp. Guidelines and information are presented for file name conventions, path specification, and background file transfer. TERMINOLOGY The following terms are used in this chapter. ASCII file, text file An ASCII or text file can be read by humans, and can be used with standard editors on the PC or host. When text files are transferred, the end-of-line markers are changed. Binary, graphics, or IMAGE file A binary, graphics, or IMAGE file cannot be read by humans. When transferred, binary files are not changed in any way (unlike text files). Client/Server The client is the system that requests services and the server is the system that provides them. The client is not always your PC, despite appearances. When you use NCSA Telnet to connect to a host, your PC is the telnet client. When you request a file transfer from your PC, the transfer is actually initiated on the host, making the host the FTP client and your PC the FTP server. So the PC is a telnet client and an FTP server at the same time. File transfer In a file transfer, the contents of a file are copied, and the copy is placed on another computer's disk drive. FILE TRANSFER GUIDELINES Full Path Specification, Conversion of Forward Slashes With either FTP or rcp, if you do not specify a full pathname, files are transferred to the default directory. If you need to specify a different directory, type the full pathname as documented in the DOS manual. The full pathname may include the disk drive name, with a colon, for example: D:\myfiles\graphics\image.dat or D:/myfiles/graphics/image.dat You may use forward slashes (/) rather than backslashes (\), because NCSA Telnet automatically converts any forward slashes in UNIX pathnames to backslashes for compatibility with PC-DOS. Because backslashes are special characters in the UNIX shell and a special format is required to enter them, forward slashes are more convenient to use. Some Simultaneous Activity Permitted With both FTP and rcp, file transfers are processed at the same time as other telnet sessions. Therefore, while a file transfer is in progress you can perform other NCSA Telnet activities such as interacting with a telnet session, switching sessions, adding new sessions, or changing parameters. However, do not initiate another file transfer while one is already in progress. While an FTP request is being processed, a second FTP request will be ignored. However, if you try to start an rcp transfer while another transfer is already underway, both transfers may fail. NOTE: Do not quit NCSA Telnet while a file transfer is in progress, or the file transfer may fail. Rules for Filenames Sent to the PC Whether you are using FTP or rcp to transfer files to or from a PC, check these rules for PC filenames: % A legal PC filename is eight characters or less, followed by an optional period and an up to three-character extension. % Upper- and lowercase are considered identical for filenames on PC disks. % Names of files which are transferred from the PC are given in all lower case. % A filename longer than eight characters is truncated. % If a period occurs in a filename, the next three characters are read as the extension, and any others are truncated. % A filename should not contain "special characters" or spaces. If it does, the file may be lost or unreadable. Examples of special characters are the asterisk (*), the dollar sign ($), the pound sign (#), the hyphen (-), and control characters. File Transfer Reports The FTP server produces several kinds of information for the local user to help keep tabs on FTP access to the local hard disk. This information can be viewed with the ALT-M command (show console messages), as documented in Chapter 2. The following list describes the information which FTP provides: % Reports when a command connection is initiated, with the IP address or host name of the remote machine which initiated the connection % Reports the name of the user who logs in, if the USER command is used % Reports the file names which were transferred to or from local disk % Reports when the command connection ends The rcp server also produces reports for the console screen. % Reports when an rcp transfer begins % Reports when the rcp transfer ends FILE TRANSFER USING FTP The FTP server in NCSA Telnet is the minimum standard FTP server, similar to that in 4.2 BSD UNIX. NCSA's FTP supports the following features: % Stream transfer in text format (ASCII) or binary format (IMAGE) % Change directory % Print current directory % List files in current directory (with wildcard specifications) % Send and receive multiple files with one command, using wildcards Prerequisites % The host machine must support FTP file transfer. If you do not know whether it does, see your system administrator. % You must not have disabled the file transfer capability of NCSA Telnet. That is done with the Parameter menu (Chapter 3), or in the configuration file (Chapter 6). If the file transfer capability has been switched off, when you attempt to start up FTP, you will get a message from the host to the effect that the computer is not responding. If you get such a message, check the file transfer mode on the Parameter menu to make sure that it is enabled. When to Use FTP Use FTP rather than rcp in either of the following situations. 1. You are not thoroughly familiar with the host operating system. FTP is easier to use than rcp, and requires less familiarity with the host commands and directory structure. 2. You are transferring PC text (ASCII) files to a host. FTP is a better choice than rcp, because FTP automatically converts the end-of-line characters in text files from CRLF used by PC- DOS, to LF used by UNIX machines. Invoking FTP on the Host Computer FTP is initiated by the host, so the FTP commands vary, depending on the host system. For full documentation of FTP and commands within FTP, you must refer to the manuals for the host computer. With UNIX systems, you can see online documentation by using the man ftp command. THE FTP COMMAND On most systems, the FTP command is entered at the prompt, with the name or IP address of the target machine. For example, if your PC is named "mymachine" and your IP address is 192.17.20.22, then you might enter: % ftp mymachine or % ftp 192.17.20.22 which generates a response like this: Connected to 192.17.20.22. 220 PC Resident FTP server, ready Name (192.17.20.22:timk): Most FTP clients will now prompt you for your username and password. If NCSA Telnet is configured for passwords (see Chapter 6), then these are required. Otherwise, just press RETURN to bypass the prompts. If you are not prompted for username and password, then assume that you are logged in and continue with your FTP commands. ALTERNATE METHODS OF INVOKING FTP (ALT-T AND ALT-I) The most common procedure for starting FTP uses the shortcut keystroke, ALT-T. When you press ALT-T, NCSA Telnet types the ftp command described above, automatically including your PC's IP address and the RETURN to initiate the command. For convenience, you will probably prefer ALT-T to the other ways of entering the command. You may want to think of this as a keyboard macro that is pre-set with the FTP command and your IP address. Another available macro is ALT-I which types your IP address for you. When entering any networking command, FTP for example, you can instantly produce your own network IP address with ALT-I. The following sequence is equivalent to pressing ALT-T. ftp (SPACEBAR) (ALT-I) (RETURN) Use whichever method of invoking FTP you feel comfortable with. Your host computer may or may not accept FTP commands as described here, so you may have to try some variations to find the easiest method for your site. Your system administrator may be able to help. FTP Commands For most FTPs, after FTP has been invoked and passwords have been checked, you are prompted for individual FTP commands. These commands are also documented in the manuals for the host computer. Most of the FTP implementations have similar commands because they are modeled after the Berkeley UNIX version of FTP. Table 4.1 lists FTP commands that are common to most implementations. Table 4.1. Common FTP Commands Command Action ascii Sets mode to ASCII transfer mode (default) binary Sets mode to binary (image) transfer mode cd path Sets a new default directory on PC dir Shows filenames in PC's default directory get filename Gets a file from PC, sends to host help Shows online list of FTP commands put filename Sends a file from host to PC pwd Shows current PC directory name quit Exits FTP ASCII, BINARY The default mode for FTP transfers is ASCII format. If you are transferring graphics or binary data files, change to binary mode before you use the put or get commands. Do this by entering the command binary. To reset the ASCII format after sending a binary file, enter the command ascii. Figure 4.1 shows an FTP transaction with an ASCII file. Figure 4.2 shows an FTP transaction with a binary file. DEFAULT DIRECTORY Unless you include a full pathname with the command, NCSA Telnet transfers the file to the default directory. As Table 4.1 indicates, you can use FTP commands to identify the current directory (pwd), or change the current directory (cd). The change directory command, which the user types as cd, allows you to change the default disk drive in addition to the default directory. Just use PC standard disk notation, with forward slashes instead of backslashes, for example: ftp> cd D:/files The pwd command also returns disk information. After the previous example cd command, a pwd command returns: D:\FILES TRANSFER TO THE PC Even though you seem to be initiating the transfer from the PC, the transaction operates from the host's side. The practical effect of this could make the commands seem intuitively "backwards." To transfer a file from the host to your PC, you use a put command. The form this command takes is: put filename.ext Figure 4.1 shows an example of a put command used with an actual file, named temp2. The boldface type represents user entries. newton_45% ftp -n 192.17.20.124 Connected to 192.17.20.124. 220 PC Resident FTP server, ready ftp> put temp2 200 This space intentionally left blank < > 150 Opening connection 226 Transfer complete 262145 bytes sent in 32.61 seconds (7.8 Kbytes/s) ftp> quit 221 Goodbye newton_46% Figure 4.1. Put to the PC, ASCII File TRANSFER TO THE HOST A request to send a file from the PC to the host is called a get. get filename.ext Figure 4.2 shows a get operation, using a binary file named bridge.pic. Note that the file was in the directory named ibmg, so the cd command was used. Again, the boldface type represents user entries. If a text file were to be sent after this, the ASCII mode would have to be reset, using the FTP ascii command. newton_41% ftp -n 192.17.20.124 Connected to 192.17.20.124. 220 PC Resident FTP server, ready ftp> bin 200 Type set to I, binary transfer mode ftp> cd /ibmg 250 Chdir okay ftp> get bridge.pic 200 This space intentionally left blank < > 150 Opening connection 226 Transfer complete 262144 bytes received in 9.22 seconds (28 Kbytes/s) ftp> ftp> quit 221 Goodbye newton_42% Figure 4.2. Get from the PC, Binary File FTP STATUS INDICATOR After you have entered a put or get command, in the lower right hand corner of your screen you will see the filename and an indication of the number of bytes transferred (in the case of a put) or left to be transferred (in the case of a get). These numbers are updated every couple of seconds to help you keep track of the progress of the file transfer. After the command has completed, the filename goes away and the host usually prints a confirmation message, as seen in Figures 4.1 and 4.2. MPUT, MGET On many telnet hosts, you can transfer multiple files sequentially with one command, either mput or mget, used with wildcard characters. (PC wildcard characters are ? for a single character and * for multiple characters.) BUG WITH MGET If you transfer multiple binary files using a UNIX host, note that there is a bug in mget as implemented on some systems (especially 4.2 BSD UNIX). When used in binary mode, mget adds a carriage return to the filenames as they are transferred. The files themselves are not affected. Use a UNIX utility to remove the carriage return from the filename. In ASCII mode, there is no problem. FILE TRANSFER USING RCP rcp is a Berkeley UNIX feature found in Sun UNIX and other 4.2 BSD systems. The rcp program cannot do the end of line translation required for text files, so it is typically used for binary files only. UNIX rcp is designed for files copied UNIX-to-UNIX, but NCSA Telnet's rcp server supports transfer between a UNIX system and a PC. NOTE: NCSA Telnet's rcp server does not support the recursive option (-r). Prerequisites To use rcp efficiently, you should be familiar with the UNIX host, including: % rcp command and options % directory structures used with rcp % the relationship between the UNIX shell and rcp wildcards Details on these concepts are in the manuals for UNIX. The internet (IP) number and machine name for each PC must be in the UNIX /etc/hosts file for every machine that is transferring files to and from your PC. If rcp does not recognize your PC's name, have your system administrator check for that name in the UNIX machine's hosts file. When to Use Rcp; Advantages of Rcp Use rcp for binary transfers to or from a UNIX system if you are familiar with the UNIX hosts, as described earlier. There are two advantages of using rcp rather than FTP, on binary file transfers to or from a UNIX machine. % rcp handles wildcards more efficiently than FTP does. % rcp handles directories more easily than FTP does. When Not to Use NCSA Telnet's Rcp Server Do not use the rcp server to transfer text files. Text files on the PC contain extra RETURN characters that NCSA Telnet's rcp server does not remove when transferring to UNIX. NOTE: Do not initiate an rcp while a file transfer is already in process, or both transfers may fail. Rcp Between the PC and UNIX The rcp program is fully documented in the manuals for UNIX hosts that support rcp transfers. Refer to those manuals to learn about rcp. As a reminder, the general syntax of the rcp command is given here. The target filename can be a directory name and wildcards are allowed, as noted in the next section. % rcp mypc:filename unixfile From PC to UNIX. % rcp unixfile mypc:filename From UNIX to PC. EXAMPLE: PC TO UNIX Following is a sample command to transfer a file named image from the PC named mypc to the current directory on the UNIX host (indicated by a dot or period). Note that the only blank spaces are after the command rcp, and between the filename and the target directory name (in this case, the dot for the current directory). % rcp mypc:image . EXAMPLE: UNIX TO PC Following is a sample command to transfer a file named mygraf in the directory graphs from the UNIX host and put it in the directory grafs on the PC. % rcp /graphs/mygraf mypc:/grafs Using Wildcards Wildcard characters can be used with the rcp command to transfer multiple files between a PC client and a UNIX host. Wildcards that refer to UNIX files should be in the UNIX regular expression format. Wildcards that refer to PC files must be set apart using backslashes or quotes. See the following examples. EXAMPLE: BACKSLASHES USED WITH WILDCARDS One way of using PC wildcards with the rcp server is to use the backslash character (\) to keep the UNIX shell from interpreting the special characters. Suppose you want to transfer all files that have image at the beginning of the filename. Instead of the usual PC format, image*.*, you must precede each asterisk with a backslash. The full rcp command would look like this: % rcp mypc:image\*.\* . Without the backslashes, the UNIX shell would try to translate the asterisk on the host rather than on the PC. EXAMPLE: QUOTES USED WITH WILDCARDS The second way of using PC wildcards with the rcp server is to insert quotes around the entire argument. The command to transfer the files beginning with image would look like this: % rcp "mypc:image*.*" . CHAPTER 5 TEKTRONIX 4014 GRAPHICS CHAPTER OVERVIEW NCSA Telnet can emulate the Tektronix 4014 graphics terminal. This emulation includes text modes, Tek 4014 text sizing, zoom, pan, and multiple output devices. It supports CGA, EGA, Hercules, and the Number Nine Revolution 512x8 video systems, with the capability to write out images in PostScript, HPGL, or Tek drawing commands. The use of Tektronix graphics with NCSA Telnet depends upon host programs that can produce graphic images. When these programs run and produce Tektronix 4014 graphics commands, NCSA Telnet automatically switches into graphics mode and does the drawing. This chapter describes steps in preparing to emulate the Tektronix 4014 and how to use the Graphics menu. BEFORE YOU BEGIN TEKTRONIX EMULATION Initializing a Plotter If you will be plotting directly to a plotter, the communications port for the plotter must be initialized before you run NCSA Telnet. This is done using the DOS mode command. See the DOS manual and the plotter manual for examples. Configuration File Settings The configuration file is used to install the hardware and software configuration for Tektronix graphics. There are several settings you should insert in the configuration file, detailed in Chapter 6, before you use Tektronix emulation. 1. You should include tek=yes in the configuration file to enable graphics operation. 2. The video type is specified with the video parameter in the configuration file. This is the only step required for selecting the video display because all of the screen drivers are included in NCSA Telnet. 3. You should install specific filenames to be used when writing each of the three different kinds of drawing commands. The hpfile parameter selects the file to receive HPGL commands, the psfile option selects the file to receive PostScript drawing commands, and the tekfile option selects the file to receive Tektronix drawing commands. If you do not make any settings here, the default files are hp.out, ps.out, and tek.out. 4. If you want HPGL output to go directly to a plotter that is connected to COM1 rather than to a disk file, add hpfile=com1 to your configuration file. Note that COM1 is used without a colon. SWITCHING TO AND FROM GRAPHICS MODE Graphics Mode When host programs produce Tektronix 4014 graphics commands, NCSA Telnet automatically switches into graphics mode and does the drawing. The exact command sequence which causes the switch to graphics mode is the Tektronix clear screen command, ESC-FF, which is sometimes written as ESC-CTRL-L. A copy of your text screen is saved while you are in graphics mode. The second way to enter graphics mode is to press CTRL-HOME. This key switches from text mode to graphics mode and clears the graphics screen. Host programs that produce Tektronix 4014 graphics commands cause the screen to automatically go to graphics mode, so you will not usually need to use CTRL-HOME to switch to graphics manually. The third method of starting graphics mode is to re-display the last graphics image. The re-display option is from the Graphics menu, described later in this chapter. At the completion of the re-display command, the screen remains in graphics mode. Text Mode To return to text mode, press HOME. When you are in graphics mode, HOME will set your display back to text mode and redraw the text screen which was visible before the graphics mode began. There is no host command which automatically returns to text mode. When you are in text mode, HOME has a different function. See Chapter 2 for details. GRAPHICS MENU (ALT-G) The Graphics menu is started with ALT-G. Figure 5.1 shows the Graphics menu, as it appears with the default file names. The fields in bold can be changed by the user. ALT-G Graphics menu < Press the appropriate function key or ESC to resume > F1 - Write postscript to a file called: ps.out F2 - Change postscript output file name F3 - Write HPGL code to a file called: hp.out F4 - Change HPGL output file name F5 - Write Tektronix 4014 codes to a file called: tek.out F6 - Change Tektronix output file name View region is currently: 0,0,4095,3119 F7 - Set a new view region (Zoom, Pan) RETURN - draw picture on screen in current zoom factor Enter choice: Figure 5.1. Graphics Menu From this menu, you press the appropriate function key, or RETURN to redraw the most recently displayed graphics picture. Writing Graphics Files to Disk To write out graphics images use the Graphics menu. First, the image should be displayed on the screen using host software that generates Tektronix images. NCSA Telnet always keeps the last graphic image in memory. Select one of the options which writes this image to disk. Images are written using the current view region. If you select Tektronix 4014 format, NCSA Telnet writes the image directly to disk and then returns you to your current session. After selecting the HPGL or the PostScript option from the Graphics menu, you are returned to your session while the file is written to disk in the background. After this image has been completely copied from memory to disk, you are notified on the console screen that the process has completed. Renaming Graphics Output Files If you did not set up alternate files to use in the configuration file and you do not want to use the default filenames hp.out, ps.out, or tek.out, you can change the names before or after writing the file. Use the Graphics menu options to change one of the current file names before writing the image to disk. If you want a name change after writing out the file, use ALT-E to escape to DOS, then use the DOS rename command. Use exit to leave DOS and return to NCSA Telnet. A special feature allows you to append the current image to an existing disk file instead of overwriting. Enter any of the three file names as you would normally, adding a plus (+) to the beginning of the name. NCSA Telnet takes the plus (+) to indicate that you want to open that file for "append", adding another image to the file. A filename which does not begin with a plus (+), causes NCSA Telnet to overwrite the file when saving each image. Set the Viewing Region (Zoom Factor) Another Graphics menu choice lets you set the viewing region, or zoom factor. Any portion of the image can be enlarged and made to fill the screen. Tektronix drawing commands are resolved to a 4096 by 3120 pixel resolution. They start with 0,0 in the lower left, and go to 4095, 3119 in the upper right. The default view region for NCSA Telnet is (0, 0, 4095, 3119), which is the full image. Figure 5.1 has examples of possible viewing regions that you can use. Figure 5.2. Sample Viewing Regions Redraw Last Image The Graphics menu option, Redraw Last Image, is used when you want to review the image that is currently in memory. This option always zooms and enlarges the image according to the view region that is visible. The selected view region always fills the screen so you can see more detail. This command leaves you in graphics mode, so press HOME if you want to return to text mode. PLOTTING A STORED FILE If you have used the Graphics menu to store a file of HPGL drawing commands, the DOS copy command can send those commands to an attached plotter (which is connected to COM1 in this example). C:> copy filename.out com1 CHAPTER 6 INSTALLATION AND CONFIGURATION CHAPTER OVERVIEW This chapter contains information for system administrators (and other experienced users) to use in installing and customizing a system. The chapter describes how to install NCSA Telnet, change the configuration file, the domain name lookup, how to protect FTP transfers with passwords, and compatibility issues. INSTALLING THE DISTRIBUTION FILES There are three files required for the standard configuration of NCSA Telnet. The combination of these with the use of the DOS path command allows you to call up NCSA Telnet from any subdirectory on your PC. TELNET.BAT This batch file begins the execution of NCSA Telnet. It must be in some directory that is in your DOS path. It contains the locations of the TELBIN.EXE and CONFIG.TEL files. You must update this batch file (with any standard editor) when you change the location of TELBIN.EXE or CONFIG.TEL. TELBIN.EXE This is the program itself. It can be in any directory. The TELNET.BAT file calls up this program when it runs. CONFIG.TEL This is the configuration file that contains your PC's IP address, the kind of Ethernet hardware that you are using, and other information about your network. Gateways, nameservers, and setup information are stored here. The TELNET.BAT file tells TELBIN.EXE where it can find this file on your disk. Sample Configuration Suppose you want to install NCSA Telnet in a directory called \ncsa on your hard disk drive, drive C. Copy the TELBIN.EXE and CONFIG.TEL files to C:\ncsa. Suppose also that you have a particular directory C:\bat, which you use to store commonly used batch files. Your DOS path (see DOS manual) contains an entry for C:\bat already. Copy the TELNET.BAT file into C:\bat. You must now edit the TELNET.BAT file to update the locations of the TELBIN.EXE and CONFIG.TEL files. When finished, it should look something like this: if .%1 == . goto defh c:\ncsa\telbin -h c:\ncsa\config.tel %1 %2 %3 %4 %5 goto exith :defh c:\ncsa\telbin -h c:\ncsa\config.tel ncsab :exith This batch file calls up TELBIN.EXE at a known location and passes it the -h parameter, indicating the location of the CONFIG.TEL file. In addition to the file locations, the fifth line indicates which machine NCSA Telnet should connect to by default. Required Configuration Information To set up a new configuration file, you will need a standard text editor. The template provided with NCSA Telnet is set up to reflect commonly used default values. It may be worth the time to go through the list of configuration options in this chapter and fine-tune your configuration to match your local computing situation more closely. In the meantime, the following fields in the configuration file must be installed for NCSA Telnet to operate. myip=192.17.20.10 You must provide a unique IP address for each machine on your network. This must be installed in the configuration file of each computer. netmask=255.255.255.0 Subnet mask, in decimal. This field is required if you are using subnets on your network. hardware=3C501 NCSA Telnet can support several different brands of Ethernet adapters. Each brand has its own unique identifier which must be set for the hardware parameter. See the hardware section in this chapter for a complete list of settings. Most brands also require address and ioaddr to be set. video=ega If you wish to use the Tektronix graphics options, you must provide the correct screen type. Incorrectly installed, this can crash NCSA Telnet. The alternative is to install the tek=no option. Legal types are cga, ega, hercules, no9. gateway=1 If you are going to be using gateways to reach other networks, at least one machine must be designated as a gateway, using this gateway option after the name field. The entry for each gateway must include a hostip field, according to the configuration file directions in this chapter. The TELNET.BAT File The actual .exe file that the PC executes is not named telnet.exe. A batch file called TELNET.BAT loads the software in several steps that are normally transparent to you. Here is a typical entry in TELNET.BAT: C:>\apps\telbin -h c:\apps\config.tel %1 %2 %3 %4 The TELNET.BAT file, which must be in the DOS path, specifies completely where the program is, and where the configuration file is to be found. There may also be a default machine name that the system connects to when you do not explicitly specify one. Command Line Options Telnet goes through two stages as you load it. The TELNET.BAT file must be in the DOS path so it can be found first. In the batch file, the location of the TELBIN.EXE file and any command line defaults are used to call up the program in the next stage. Many command line arguments are included for you in the batch file, TELNET.BAT; you add others when you run the telnet batch file. This is a full description of those options. The syntax for loading NCSA Telnet with options is: C:\ > telnet [options] [machine1 machine2 ...] The options must precede the list of machine names on the command line. Options can be in any order; parameters on options are required. There must be one space between the options and between each option and the parameter for that option. The options are: ? Shows command line options. This causes NCSA Telnet to display a summary version of the command line options instead of initiating the program. -c colorcode Sets the default color for screens. The colorcode string is six digits long and follows the coding scheme documented later in this chapter. -h filename Specifies where to find the configuration file. Normally, this option is included in TELNET.BAT, and you never have to use it explicitly. If the configuration file is not specified there or on the command line, there must be a file named CONFIG.TEL in the default directory. If a suitable configuration file cannot be found according to these rules, NCSA Telnet terminates. NOTE: filename should include a pathname. For example, C:\bat\config.tel -s Enters server mode. NCSA Telnet waits for external FTP and rcp requests. It allows you to leave your PC and access files there from a remote machine. -t Disables direct writes to the screen. Without the -t option, NCSA Telnet defaults to writing directly to screen memory. This greatly enhances the screen speed, but makes NCSA Telnet incompatible with Topview, Microsoft Windows, and other windowing systems. To make NCSA Telnet completely compatible with BIOS-level programs, use the -t option. This option can be permanently installed in the TELNET.BAT file or the CONFIG.TEL file (bios option). THE CONFIGURATION FILE Overview of the Configuration File The configuration file replaces the hosts file of NCSA Telnet Version 1.2. This file contains information on local operating parameters (such as which type of graphics screen your PC has, and your IP number), plus a list of commonly accessed hosts and optional network tuning parameters for each of those hosts. The configuration file is accessed once when the program is initiated and is not used again. All of the machine names are read into memory, so it may save memory to limit the number of computers you specify in the file. The configuration file is typically named CONFIG.TEL. If this file is in the default directory, it will be found automatically, but the use of the -h flag in the TELNET.BAT file is recommended. Syntax for Entries in the Configuration File The configuration file is a list of keywords and values for those keywords. The one overall requirement for the entries in the file is that they alternate, keyword then value, keyword then value, and so on. There are many different formats possible using any of the allowable delimiters. The delimiters are the colon (:), semicolon (;), equal sign (=), and any of the whitespace characters. To include delimiters in a value field, enclose the field in double quotes. Quotes cannot be a part of the actual data field. Wherever a pound sign (#) is found, everything from there to the end of line is a comment. Though multiple formats can be used in the same file, you will probably want to find and keep a consistent format. For example, each of the entries in Figure 6.1 specify the same information. Note that example #3 is not a recommended format, but is included to show how strange an entry may look. name=nic # comment field to end of line -> host=sri-nic.arpa hostip=10.0.0.51 scrollback=300 contime=60 - - - - - -Example #1- - - - - - - - - name=nic; host=sri-nic.arpa; hostip="10.0.0.51"; scrollback=300; contime=60 - - - - - -Example #2- - - - - - - - - name nic host sri-nic.arpa : hostip=10.0.0.51; scrollback=300; contime:60 - - - - - - Example #3- - - - - - - - - Figure 6.1. Displaying the Same Information in Different Entry Formats PC Information Entries in the Configuration File The first entries in the configuration file are the PC environment entries. They specify what types of hardware are to be used, names of graphics output files, and network configuration information. Here is the list: myip=10.0.0.51 This is the IP address to use for the PC. This number must contain all four parts of the IP address. This field is required. myip=RARP This is a special form of the myip entry. Setting myip to RARP will cause NCSA Telnet to query a RARP server to get its IP address. See the section on RARP in this chapter. netmask=255.255.255.0 This is the subnet mask for your local network. It is optional for networks without subnets. arptime=3 Specify how long to try to reach a host on the local wire, in seconds. A value of 2 works fine for the network at NCSA, but larger values may be needed for hosts that are slow to respond. Smaller values are more convenient to use. domain="ncsa.uiuc.edu" This entry in the configuration file affects hostname lookups which are sent to the domain nameserver. All names which do not contain a period have the default domain appended before the nameserver request goes out. If the hostname you type contains a period, then the name is unmodified before NCSA Telnet sends it to the nameserver. There is no "ring-down" or multiple lookup feature to try more than one form of the name. domaintime=2 Time in seconds to wait between the first domain lookup and the second. If you only have one nameserver, then this is the same as a simple timeout. If you want to rotate nameservers quickly because the first one may be down, set this to a smaller number. To force a larger number of retries, set this to a smaller number. To wait longer for a domain response, increase this value. domainretry=4 Number of times to query domain nameserver(s). Each time a retry is sent, the timeout value (above) is doubled. Each time a retry occurs, NCSA Telnet tries the next nameserver, wrapping around to the first nameserver when there are no more. tek=yes There is no overhead to unused Tektronix graphics emulation, but you may wish to disable graphics support. tek=no will disable Tektronix graphics emulation. video=ega Tektronix 4014 graphics emulation is included in NCSA Telnet for a variety of video devices. Supported are: hercules (Hercules monochrome graphics), cga (IBM and compatibles original Color Graphics Adapter), ega (IBM Enhanced Graphics Adapter and compatibles), and no9 (Number Nine Computer's Revolution 512 x 8 board). bios=no NCSA Telnet has two screen-writing modes. One is direct-to-screen (bios=no) which is considerably faster on most machines. The other uses BIOS (bios=yes) and follows the IBM BIOS conventions at all times. BIOS mode makes NCSA Telnet compatible with popular windowing systems and can reduce the amount of flicker and snow on the screens of IBM CGA-equipped systems. hardware=3C501 NCSA Telnet can support several different brands of Ethernet adapters. Each brand has its own unique identifier which must be set for the hardware parameter. See the hardware section in this chapter for a complete list of settings. interrupt=3 There are several choices for interrupt vector on the 3COM 3C501 Etherlink board. NCSA Telnet defaults to IRQ3, but can be set to use different interrupts by indicating the interrupt number here. Match this number with the interrupt setting from your Etherlink board. address=d000 This is the segment address of the Ethernet board's shared memory, entered as four hex digits. This only applies to boards that have jumpers or registers which can be used to set the shared memory address. After setting the board's jumpers to a particular value, use the address parameter to configure NCSA Telnet with the same setting. d000 (hex) is a common address to use and it rarely conflicts with other boards. ioaddr=360 This is the I/O base address of the Ethernet board in hex. Some Ethernet boards have selectable I/O addresses. These generally range from 200 to 400 (hex) and must be entered as two, three, or four digits. ftp=yes FTP serving is enabled by default. Access to your PC can be controlled by the FTP password file. To disable FTP serving completely, change this line to ftp=no. rcp=yes rcp serving is enabled by default. To disable rcp serving, change this line to rcp=no. capfile= Specify a name for the capture file. For example, capfile ="c:\temp\myfile" When you capture to disk, all data is appended to this file. If no name is included in the configuration file, capfile is used by default. capfile=prn Specifies that the printer device (PRN) should be used for the capture file. hpfile=hp.out Tektronix graphics can be dumped to a file in several formats from the Graphics menu. When you write out HPGL (HP plotter) codes, this file name is used. For example, hpfile="c:\hpgrafs\hp.out" The default is hp.out in the current directory. hpfile=COM1 With an HP plotter hooked up to your PC, HPGL plotter codes can be sent directly to the plotter. Use the mode command to preconfigure the serial port first. psfile=ps.out PostScript commands can be printed by several types of available laser printers. NCSA Telnet's PostScript output has been tested on the Apple (Sun) LaserWriter, which is connected to Sun workstations. The default filename is ps.out in the current directory. tekfile=tek.out Tektronix 4014 graphics commands are a very compact way to store a Tektronix graphics image. This option specifies the filename to use when you write Tektronix codes to disk. The default name is tek.out. passfile= Specify the file in which FTP usernames and passwords can be found. For example, passfile="c:\bat\ftppass" There is no default name for this file. If the file is specified, then FTP will require a username and password for all attempted FTP connections. If the file is not specified, then there is no password checking for FTP. Use the program TELPASS.EXE to encrypt new passwords. See the FTP Password Protection section later in this chapter. Host-Specific Parameters of the Configuration File Following the PC configuration options, you may specify zero or more hosts, and host-specific information for each host. By making the host entries in the configuration file, you can specify color, backspace, scrollback, connection timeout, and several tuning parameters for each host. You may want to have more than one session name associated with a single computer, such as purple cray and red cray with different screen colors to fit your mood of the day. Typically, the first host listed will be name=default, which stores the default values for the other hosts. Any keyword listed under later hosts will override the default setting for that host session. NOTE: The keyword name is special because it separates entries. The parameters following name up to the next keyword name are all associated with the session name. The parameters are installed whenever a connection is opened with that session name. name=nic The name that you want to appear on the bottom line of the screen when the connection opens. It is the primary name associated with a list of parameters. It is common to have more than one session name for a host, each with different parameters, perhaps with different colors or different amounts of scrollback. This parameter is required because it separates entries. host=sri-nic.arpa This is the hostname or alternate name. If you want to associate both a session name and a hostname with a particular set of parameters, you may include both. Note that the name parameter is required, while the host parameter is optional. The rule of thumb is: When you have only a hostname, insert it as name=hostname. If you have both a session name and a hostname, enter both name=sessionname and host=hostname. When you want to open a new connection, either hostname or sessionname works. hostip=10.0.0.51 This is the IP address of the host. If this is not present, the domain nameserver must be queried to get the IP number of the host. For efficiency, include the IP addresses of all commonly accessed hosts. IP addresses of gateways and nameservers must be in the configuration file. copyfrom=nic The copyfrom parameter is probably the most important one. It causes all unspecified parameters to be copied from a previous session name. Note that the session name which you want to reference with copyfrom must appear before the session name that uses a copyfrom directive. Parameters that are specified for a session name along with a copyfrom directive override that copyfrom directive. gateway=1 This specifies the gateway precedence for this host. To reach hosts not connected to your local network, you must have at least one gateway entry. The hostip keyword must be present for this host. Gateway numbers must start at 1 and increase by ones. Gateway 1 has the highest precedence, but the first gateway to respond to an ARP will be used. ICMP redirects can affect how gateways are used, but not permanently. nameserver=1 This specifies the nameserver precedence for this host. NCSA Telnet uses UDP to query domain nameservers for machinenames that are not in the configuration file. Each machine that is to be used as a nameserver must have this keyword listed. The hostip keyword must be present for this host. Nameserver 1 has the highest precedence. Nameserver numbers must start at 1 and increase by ones. nfcolor=white normal, foreground nbcolor=black normal, background rfcolor=black reverse, foreground rbcolor=white reverse, background ufcolor=blue underline, foreground ubcolor=black underline, background These new color options can be used instead of the more complicated color code from previous versions. For each value, specify a string from the following list of colors available on IBM-PC class machines with color displays: black blue (underline on mono screen) green cyan red magenta yellow white The foreground and background colors are combined to create the text appearance on the screen. You may wish to experiment with the Parameter menu (Chapter 3), which interactively allows you to select a color scheme. The previous version's color= entries are still supported. scrollback=100 This specifies the number of lines of scrollback for this session. Be aware that scrollback occupies at least 86 bytes per line saved. There can be a different number of lines of scrollback for each session. Plan your use of scrollback wisely unless you have memory to spare. clearsave=yes Scrollback is updated when the screen is cleared. When clearing the screen, all of the visible lines are saved into the scrollback region. If you prefer not to have the text saved when the screen clears, set clearsave=no. In the case of host programs which clear the screen one line at a time, the lines are never saved into the scrollback region. erase=delete This sets the backspace translation for this host. Some hosts prefer the backspace key to be DELETE and some prefer the backspace key to be BACKSPACE. Set this value erase=delete or erase=backspace. crmap=4.3BSDCRNUL This is a special compatibility option for 4.3 BSD UNIX. There is now a UNIX bug fix to take care of the problem, but some hosts may still want crnul to be used for end-of-line. The default is crmap=crlf, which sends CRLF when you press RETURN. In line mode, CRLF is always used. duplex=half This parameter only applies to hosts that negotiate non-echoing mode but do not expect local line editing. All character keys are sent and echoed to the screen immediately. This parameter has no effect in echo mode. contime=10 This is the connection timeout in seconds. When you are making a connection attempt, after this amount of time has elapsed NCSA Telnet gives up on opening the connection and deletes the window. For congested or slow networks, this value should be made larger. retrans=7 This is the initial retransmit timeout in 18ths of a second. Increasing the value of this parameter may help in reducing the initial burst of retries that is typical of connections with high round-trip times. mtu=512 This is a byte count (1-1024) of the largest amount of data to put in the packets that are sent. If you are sending to the ARPANET you should use mtu=512. If you are sending to local hosts, you should use mtu=1024. maxseg=512 This is a byte count (1-1024) of the largest TCP segment that can be received. This value can control the size of packets that are sent over the connection. Reducing this value can eliminate IP fragmentation that we cannot reassemble. maxseg=512 should force the sending host to never fragment. rwin=512 This is a byte count (1-4096) of the largest size of the TCP window to advertise to other hosts. Unfortunately, some hardware and networks, the 3COM 3C501 Etherlink for example, cannot handle receiving back-to-back packets. This requires us to limit the TCP receive window that we advertise to other hosts. For communicating to slower hosts, or when using the other brands of Ethernet boards, a larger window (4096) may work better. Converting UNIX /etc/hosts Files Included with the distribution is an awk script called newh. Used with the following command under 4.X BSD UNIX, it will convert the /etc/hosts file format into a format compatible with NCSA Telnet's configuration file. Note that domain name lookup should make this operation obsolete, or apply to only a small subset of your /etc/hosts file. % awk -f newh /etc/hosts >config.temp After creating this new file, prepend the PC-specific information and download the file to the PC. HARDWARE OPTIONS Combined Ethernet Drivers There is only one distribution program for NCSA Telnet Version 2.2. All of the Ethernet and video device drivers are combined into one executable program. You must use the hardware entry in the configuration file to inform NCSA Telnet which Ethernet board you have installed. Choose from the list of supported Ethernet boards in Table 6.1; the value to use is case insensitive. The requirements for interrupt, address, and ioaddr entries in the configuration file are listed. Table 6.1. Ethernet Boards Supported by NCSA Telnet hardware= Value Ethernet Board Requires For PC bus - 3C501 3COM 3C501 Etherlink interrupt,ioaddr PCNIC Ungermann-Bass PC-NIC address,ioaddr or IBM Baseband adapter NI5210 MICOM NI5210 address,ioaddr WD8003 Western Digital WD8003E address,ioaddr For PS/2 MCA bus - NICps2 Ungermann-Bass NICps/2 address 3C523 3COM 3C523 Etherlink/MC address,ioaddr Performance Tuning The values of maxseg, mtu and rwin in the configuration file must be set correctly to get maximum data transfer throughput between machines. There are some rules of thumb to use when setting these values. % The maximum reasonable values for these parameters are: rwin=4096 mtu=1024 maxseg=1024 % The best setting for local network use, with a high performance Ethernet board is: rwin=4096 mtu=1024 maxseg=1024 % The best setting for ARPANET use, or any situation with a lot of unknown gateways, but with a high performance Ethernet board is: rwin=4096 mtu=512 maxseg=512 % The setting required for the 3COM 3C501, and any other troublesome network situation, also the most conservative setting, is: rwin=512 mtu=512 maxseg=512 rwin specifies what the other computer is allowed to send you at any one time, so it depends mostly upon your local Ethernet board. If the board can handle it, always set rwin=4096. maxseg is used to avoid fragmentation. If you get fragmented packets, lower the value of maxseg for that host until fragmentation stops occurring. RARP for Dynamic IP Address Assignment myip=RARP When this special form of the myip entry is used, NCSA Telnet looks up your local machine's IP address with a broadcast request to the network. The "Reverse Address Resolution Protocol" is used to attempt to translate the local machine's assigned 48-bit Ethernet address to a corresponding IP address. From our tests with the RARP server from Sun Microsystems' SunOS 3.X, the RARP lookup takes about 3 seconds. You must install the 48-bit Ethernet address from each PC in the RARP hosts' tables before RARP will work. The value of arptime, in seconds, multiplied by three, is used for a timeout value. NOTE: Sun's RARP lookup will not work if you have a double-zero in your Ethernet address. Other leading zeros can be dropped as well. Use a single zero, i.e. 8:0:20:1:5a:90, instead of 08:00:20:01:5a:90. Interrupts When you configure the 3COM hardware, an important option is the choice of interrupt request number (level). 3COM boards arrive set for IRQ3, which corresponds to the PC-DOS definition of the COM2 communications port. If you have a port configured as COM2, you cannot set your Ethernet board to IRQ3. Another common value to use is IRQ5, which is the same interrupt that DOS uses for LPT2. Make sure that your PC hardware configuration does not conflict in any way. WARNING The most common hardware problem is interrupt conflicts. PCs have a limited number of interrupts, and you cannot have two devices which expect to use the same interrupt. PC Ethernet boards almost always consume an interrupt, even though we do not use interrupts for all Ethernet boards. Interrupts are also used by COM ports and LPT ports in your machine. You must check for conflicts. Even though it works, it may stop working. Interrupt conflicts don't always show up right away. They are software controlled. If the interrupt on your COM2 port is not activated, it may not conflict with a 3C501 board on IRQ3 until next week when you try to use a modem terminal emulator and then switch to NCSA Telnet. NCSA Telnet might work fine until you try to FTP to your hard disk; then disaster strikes. Hard disks use interrupts too. We have traced two serious hard disk problems to interrupt conflicts. IRQ2 is the default setting for some Ethernet boards when they come out of the box. On a PC-AT, this interrupt is used for the second interrupt controller, and a conflict can shut off the whole second controller which includes the hard disk. On the PC/XT and PC compatible computers, IRQ5 is sometimes assigned to the hard disk rather than LPT2. Strange hard disk problems like disk write errors may be caused by the Ethernet conflicting with the hard disk. Moral: Set your Ethernet board to an unused interrupt. DOMAIN NAME LOOKUP When NCSA Telnet cannot find a name in the configuration file, it can still find the IP number if you are running a domain nameserver. To use the domain system, at least one host must be running the nameserver and the configuration file has a nameserver entry for that host. There may be more than one. If one nameserver fails to respond, the one with the next higher precedence is queried. As soon as a response is received, NCSA Telnet will add its name to the status line and attempt to open a telnet connection. Domain Search Order When you enter a name to open a connection, there is a specific search order: 1. The name is looked up as a session name from the configuration file. 2. The name is looked up as a hostname from the configuration file. 3. The name is sent as a domain query to the first nameserver. 4. If the domain request times out, the query is repeated, but to another nameserver. This is repeated until the maximum number of retries is reached or a response is received. With the domain nameserver, the number of hosts in the configuration file can be kept to a minimum. Each host in the configuration file will be a commonly used computer that may have special screen color or scrollback requirements. The IP addresses for rarely used hosts will be accessible if the domain name retrieval system can resolve those hosts. FTP PASSWORD PROTECTION The presence of the passfile keyword in the configuration file enables FTP password protection. If you have a password file, FTP will not allow any FTP connections to open without a correct username and password. You can have several usernames and individual passwords for each user. The password file can be easily read by typing out the file. The passwords are encrypted, but not with a secure encryption system. Only trusted users should be allowed access to the password file. To create or change passwords for users, run a separate program called Telpass. This program reads in the password file so you can add and change users and passwords. There are no special installation instructions for Telpass as it is menu-driven. Start up Telpass from DOS with the name of the password file that you wish to edit. C:\ telpass pwfile Telpass automatically saves the list of names and passwords when you exit. Just add a passfile option to your configuration file to enable FTP passwords. COMPATIBILITY NOTES Ping NCSA Telnet responds to ping (ICMP echo) requests. This is used by other hosts to determine whether your PC is online. VT102 The VT102 emulator is nearly complete. VT102 features not emulated are double width and double height characters, VT52 mode, origin mode for cursor positioning, and 132 column mode. Included in the emulator are variable spaced tabs, graphics characters, keypad modes, and character attributes. FTP The FTP server in NCSA Telnet is close to the DARPA specification of the minimum implementation. Exceptions are: % The command connection does not perform telnet negotiation. % Block mode of FTP is not supported. % Some error conditions may display as command not understood instead of returning more appropriate messages. FTP has not been thoroughly tested on low-bandwidth or low- reliability networks. It should be most successful on local networks, with unknown throughput for long-haul or satellite networks. Terminate and Stay Resident (TSR) Programs Programs such as SideKick from Borland International Inc. take complete control of the PC when they are initiated with key sequences. The use of these programs does not crash NCSA Telnet, but it suspends the network communications capability while the TSR program is active. When network communications are suspended, whether from the ALT-E DOS escape feature or from using TSR programs, it takes the host approximately one minute to decide that your PC has crashed, and then it cuts you off. As long as these programs are used for short (less than 30 seconds) intervals, you should have no problem. Telnet The standard telnet protocol has several potential options that can be invoked if both parties of the telnet connection agree. NCSA Telnet refuses most of these options, but accepts the following: echo, option 1; and suppress go ahead, option 3. There are some obscure features of telnet that are not implemented in this version: out-of-band interrupts are not available, go ahead signals do nothing, and telnet acknowledge signals are not acknowledged. If there are any problems with the limitations of NCSA Telnet, please submit a bug report. Limitations There is a 20-session limit for NCSA Telnet. This is somewhat arbitrary and may be altered if there appears to be a need for it. NCSA Telnet can run out of memory, often before the 20-session limit. You are notified on the screen if this happens. APPENDIX A ERROR CONDITIONS Most of the error conditions in NCSA Telnet are nonfatal. The most important and common error messages are listed here with a short summary of the symptoms and causes. The following messages may appear on your screen during the operation of NCSA Telnet. Any other messages that appear are protocol-specific messages that require additional diagnosis from the system administrator. If a message that is not documented here occurs repeatedly, please contact your system administrator first, and if no solution is found, submit a bug report as included in this manual. Cannot find or open hosts file Cause: NCSA Telnet will not operate without a configuration file that contains the PC's IP address. This file could not be found. Solution: The configuration file can be either in the current directory, or it can be specified with the -h parameter on the command line. This is normally customized in TELNET.BAT. Your system administrator should check your installation and make sure the configuration file is there. Host machine not in hosts file Cause: You have entered a machine name that cannot be found in the configuration file. This usually is caused by a misspelling. Solution: Check that the name you entered was spelled correctly. If you want this computer to be accessed by name, add its name and IP address to your configuration file. ICMP: Destination unreachable Cause: Another machinePPprobably the gatewayPPhas determined that your message cannot reach its destination from your system. Solution: Check the IP address in your configuration file. Notify your system administrator that the gateway cannot connect you to the destination you want to reach. There may be a problem with the gateway. ICMP: Echo requested (ping requested) Cause: Someone has "pinged" your machine. Solution: No action is required; you are just being notified that a program on another computer has tried to determine if your machine is alive and connected to the network. Your machine answered "yes". ICMP: Redirect, another gateway is more efficient Cause: NCSA Telnet is sending packets to a gateway that is reforwarding them onto your local network. You will get one of these messages for each packet until NCSA Telnet adjusts the local tables and automatically switches to the correct gateway. Solution: NCSA Telnet responds to these messages and automatically switches to the correct gateway, so you don't have to take any action. You may want to change the gateway assignments in your configuration file to use a more appropriate gateway. Some situations will always produce redirects. Local HOST or gateway not responding Cause: Possible reasons this error occurs are: network problem, a configuration file problem, the computer you want to connect to is down, or the gateway that you need is down. Solution: If the computer is on your local network, check to see that the network is up and running. If the computer is not on your local network, check to see if the gateway is up and running. Ask the system administrator to check the specification of the gateway (gateway=) in your configuration file. Check the IP number of the computer that you are trying to connect to. Check to make sure that your computer is attached to the network. Check the integrity of the network cable. Memory allocation error, cannot open port Cause: Your system ran out of memory. This is the most common barrier to opening more sessions. Solution: Log off of some of your sessions or provide more memory in which NCSA Telnet can run. Providing more memory may mean buying more or rearranging your windowing system to allow more memory. NCSA Telnet Version 2.2 requires about 250K of memory plus 15K per session. In addition, scrollback requires 86 bytes per line. Network jammed, probable break in wire Cause: The PC's Ethernet board could not transmit a packet due to a low- level hardware error. Solution: The system administrator should ensure that the Ethernet T connector or transceiver is correctly connected to the back of your PC, then check the integrity of the Ethernet wire according to Ethernet specifications. There could be a short circuit in the wire, but the usual cause is that the wire has been disconnected somewhere. No internal TCP ports available Cause: You are trying to do too many activities at the same time, or some combination of your activities has not closed the TCP sessions correctly. This will happen if you open too many sessions to other computers. Solution: Close some of your existing sessions. If necessary, exit the program by logging off of all of the other computers, then restart NCSA Telnet. Packet received for invalid port -- reset sent Cause: Some other computer is sending you packets that NCSA Telnet does not expect or understand. This often happens when you press ALT-F3 to exit NCSA Telnet and then start it back up again. It can happen under a variety of network breakdown conditions. Solution: Do not press ALT-F3 to exit NCSA Telnet. If you already have, or some other network breakdown caused the problem, the other computer will eventually time out and stop sending you the extra packets. If you continue to receive them, notify your system administrator. Reset received: syn sent Cause: The machine to which you are attempting to connect is refusing your telnet connection. Solution: Check to see why that machine is not up and running. If it is, check your configuration file to see if you are using the correct IP number. APPENDIX B NCSA TELNET COMMAND REFERENCE Key(s) Action ALT-A Adds a session ALT-N Next session ALT-M Message screen ALT-E Escapes to DOS shell ALT-G Graphics menu ALT-C Capture file toggled on/off ALT-R Resets VT102 screen ALT-H Help screen ALT-T Starts file transfer as if typed: ftp [internet address] ALT-I Sends internet address to host as if typed ALT-S Skips scroll, jumps ahead ALT-P Changes a parameter; one of: color, capture file name, backspace, session name, screen mode ALT-F3 Aborts NCSA Telnet completely. Strongly discouraged ALT-Y Interrupts process ALT-O Aborts output ALT-Q Are you there? ALT-U Erases line ALT-K Erases character Key(s) Action ALT-X Closes connection HOME Exits graphics mode CTRL-HOME Clears/enters graphics mode SCR LOCK Pauses/restarts screen (do not use CTRL-NUM LOCK) SCR LOCK Enters/exits scrollback mode APPENDIX C CONFIGURATION FILE SUMMARY This appendix contains a quick reference list of the keyword values which are allowed in a NCSA Telnet configuration file. There are two sections, the first list contains the PC configuration entries which apply to the overall program or to all sessions. The second section contains the list of attributes which may be assigned to individual sessions. Each keyword has an example value and a one-line summary of its purpose. For details on allowed values, see Chapter 6, Installation and Configuration. A template CONFIG.TEL file is included on the distribution disk. LOCAL CONFIGURATION myip=10.0.0.51 IP address to use for the PC. myip=RARP Query the RARP server for my IP address. netmask=255.255.255.0 Subnet mask for your local network. arptime=3 Local network timeout for ARP requests. domain="ncsa.uiuc.edu" Default domain suffix. domaintime=2 Domain lookup timeout per retry. domainretry=4 Number of times to query domain nameserver(s). tek=yes Enable/Disable Tektronix graphics mode. video=ega Video display to use: cga, ega, hercules, no9. bios=no Use BIOS or write directly to screen. hardware=3C501 Type of Ethernet hardware to use: 3C501, PCNIC, NI5210, WD8003, 3C523, NICPS2 interrupt=3 Interrupt number for 3C501 board. address=d000 Segment address of the Ethernet board's shared memory in hex. ioaddr=360 I/O base address of the Ethernet board in hex. ftp=yes FTP server enable/disable, default is yes. rcp=yes rcp server enable/disable, default is yes. capfile="\mycapture" Specify a name for the capture file. capfile=prn Capture file is printer device (PRN). hpfile=hp.out HPGL codes for graphics go to this filename. hpfile=COM1 HP plotter attached to COM1. psfile=ps.out Filename for PostScript output. tekfile=tek.out Filename for Tektronix 4014 codes when output to disk. passfile="\mypasswd" Filename for FTP usernames and passwords. HOST-SPECIFIC PARAMETERS NOTE: The keyword name is special because it separates entries. name=nic Session name, separates lists of parameters for sessions. host=sri-nic.arpa Hostname or alternate name. Usually full domain name. hostip=10.0.0.51 IP address of the host. Required if nameserver not used. copyfrom=nic Copy all missing parameters from a previous session. gateway=1 Gateway precedence, starts at 1, goes up by ones. nameserver=1 Nameserver precedence, starts at 1, goes up by ones. nfcolor=white Normal, foreground color. nbcolor=black Normal, background color. rfcolor=black Reverse, foreground color. rbcolor=white Reverse, background color. ufcolor=blue Underline, foreground color. ubcolor=black Underline, background color. Black, blue, green, cyan, red, magenta, yellow, or white. scrollback=100 Number of lines of scrollback for this session. clearsave=yes Save cleared screen into scrollback region. erase=delete BACKSPACE key is set to "backspace" or "delete". crmap=4.3BSDCRNUL Use a different set of codes for carriage return. duplex=half Local echo, but sends all characters immediately. contime=10 Connection timeout in seconds. retrans=7 Initial retransmit timeout in 18ths of a second. mtu=512 Limit on outgoing packet size. maxseg=512 Limit on incoming packet size, given as TCP MSS option. rwin=512 TCP receive window, can make up for low performance hardware. BUGS AND SUGGESTIONS We would appreciate notification of any bugs you have found and suggestions that you might have. You may send an electronic mail message to (Internet format): telbug@ncsa.uiuc.edu or send this report by mail to: NCSA TELBUG 152 Computing Applications Building 605 E. Springfield Ave. Champaign, Illinois 61820 Name: Installation: Address (Electronic): Address (U.S. Mail): Telephone: ( ) - Version of NCSA Telnet and IBM System software: Description of Problem/Suggestion: