811 lines
31 KiB
Plaintext
811 lines
31 KiB
Plaintext
<!-- This is an SGML document in the linuxdoc DTD of the Tutorial for
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Configuring a FreeBSD for Dialup Services by Guy Helmer.
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$Id: dialup.sgml,v 1.10 1996/05/24 19:33:31 jfieber Exp $
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<!DOCTYPE linuxdoc PUBLIC "-//Linux//DTD linuxdoc//EN">
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<article>
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<title>
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Configuring FreeBSD for Dialup Services
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<author>Guy Helmer, <tt/ghelmer@alpha.dsu.edu/
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<date>v0.1, 28 March 1995
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<abstract>
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-->
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<sect><heading>Dialup access<label id="dialup"></heading>
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<p><em>Contributed by &a.ghelmer;.</em>
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This document provides suggestions for configuring a FreeBSD system to
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handle dialup modems. This document is written based on the author's
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experience with FreeBSD versions 1.0, 1.1, and 1.1.5.1 (and experience
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with dialup modems on other UNIX-like operating systems); however,
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this document may not answer all of your questions or provide examples
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specific enough to your environment. The author cannot be responsible
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if you damage your system or lose data due to attempting to follow the
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suggestions here.
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<sect1><heading>Prerequisites<label id="dialup:prereqs"></>
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<p>
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To begin with, the author assumes you have some basic knowledge of
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FreeBSD. You need to have FreeBSD installed, know how to edit files
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in a UNIX-like environment, and how to look up manual pages on the
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system. As discussed below, you'll need certain versions of FreeBSD,
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and knowledge of some terminology & modem and cabling.
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<sect2><heading>FreeBSD Version</heading>
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<p>
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First, it is assumed that you are using FreeBSD version 1.1 or higher
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(including versions 2.x). FreeBSD version 1.0 included two different
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serial drivers, which complicates the situation. Also, the serial
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device driver (<tt/sio/) has improved in every release of FreeBSD, so
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more recent versions of FreeBSD are assumed to have better and more
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efficient drivers than earlier versions.
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<sect2><heading>Terminology</heading>
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<p>
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A quick rundown of terminology:
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<descrip>
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<tag/bps/ Bits per Second - the rate at which data is transmitted
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<tag/DTE/ Data Terminal Equipment - for example, your computer
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<tag/DCE/ Data Communications Equipment - your modem
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<tag/RS-232/ EIA standard for serial communications via hardware
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</descrip>
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If you need more information about these terms and data communications
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in general, the author remembers reading that <em/The RS-232 Bible/
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(anybody have an ISBN?) is a good reference.
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When talking about communications data rates, the author does notuse
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the term <bf/baud/. Baud refers to the number of electrical state
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transitions that may be made in a period of time, while <bf/bps/ (bits
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per second) is the ``correct'' term to use (at least it does not seem
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to bother the curmudgeons quite a much).
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<sect2><heading>External vs. Internal Modems</heading>
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<p>
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External modems seem to be more convenient for dialup, because
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external modems often can be semi-permanently configured via
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parameters stored in non-volatile RAM and they usually provide lighted
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indicators that display the state of important RS-232 signals.
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Blinking lights impress visitors, but lights are also very useful to
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see whether a modem is operating properly.
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Internal modems usually lack non-volatile RAM, so their configuration
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may be limited only to setting DIP switches. If your internal modem
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has any signal indicator lights, it is probably difficult to view the
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lights when the system's cover is in place.
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<sect2><heading>Modems and Cables</heading>
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<p>
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A background knowledge of these items is assumed
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<itemize>
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<item> You know how to connect your modem to your computer so that the
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two can communicate (unless you have an internal modem, which does not
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need such a cable)
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<item> You are familiar with your modem's command set, or know where
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to look up needed commands
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<item> You know how to configure your modem (probably via a terminal
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communications program) so you can set the non-volatile RAM
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parameters
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</itemize>
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The first, connecting your modem, is usually simple - most
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straight-through serial cables work without any problems. You need to
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have a cable with appropriate connectors (DB-25 or DB-9, male or
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female) on each end, and the cable must be a DCE-to-DTE cable with
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these signals wired:
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<itemize>
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<item> Transmitted Data (<tt/SD/)
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<item> Received Data (<tt/RD/)
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<item> Request to Send (<tt/RTS/)
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<item> Clear to Send (<tt/CTS/)
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<item> Data Set Ready (<tt/DSR/)
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<item> Data Terminal Ready (<tt/DTR/)
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<item> Carrier Detect (<tt/CD/)
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<item> Signal Ground (<tt/SG/)
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</itemize>
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FreeBSD needs the <tt/RTS/ and <tt/CTS/ signals for flow-control at
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speeds above 2400bps, the <tt/CD/ signal to detect when a call has
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been answered or the line has been hung up, and the <tt/DTR/ signal to
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reset the modem after a session is complete. Some cables are wired
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without all of the needed signals, so if you have problems, such as
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a login session not going away when the line hangs up, you may have a
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problem with your cable.
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The second prerequisite depends on the modem(s) you use. If you do not
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know your modem's command set by heart, you will need to have the
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modem's reference book or user's guide handy. Sample commands for USR
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Sportster 14,400 external modems will be given, which you may be able
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to use as a reference for your own modem's commands.
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Lastly, you'll need to know how to setup your modem so that it will
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work well with FreeBSD. Like other UNIX-like operating systems,
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FreeBSD uses the hardware signals to find out when a call has been
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answered or a line has been hung up and to hangup and reset the modem
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after a call. FreeBSD avoids sending commands to the modem or
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watching for status reports from the modem. If you are familiar with
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connecting modems to PC-based bulletin board systems, this may seem
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awkward.
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<sect2><heading>Serial Interface Considerations</heading>
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<p>
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FreeBSD supports NS8250-, NS16450-, NS16550-, and NS16550A-based EIA
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RS-232C (CCITT V.24) communications interfaces. The 8250 and 16450
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devices have single-character buffers. The 16550 device provides a
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16-character buffer, which allows for better system performance.
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(Bugs in plain 16550's prevent the use of the 16-character buffer, so
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use 16550A's if possible). Because single-character-buffer devices
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require more work by the operating system than the 16-character-buffer
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devices, 16550A-based serial interface cards are much prefered. If
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the system has many active serial ports or will have a heavy load,
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16550A-based cards are better for low-error-rate communications.
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<sect1><heading>Quick Overview</heading>
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<p>
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Here is the process that FreeBSD follows to accept dialup logins. A
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<tt/getty/ process, spawned by <tt/init/, patiently waits to open the
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assigned serial port (<tt>/dev/ttyd0</tt>, for our example). The
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command <tt/ps ax/ might show this:
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<tscreen><verb>
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4850 ?? I 0:00.09 /usr/libexec/getty V19200 ttyd0
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</verb></tscreen>
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When a user dials the modem's line and the modems connect, the <tt/CD/
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line is asserted by the modem. The kernel notices that carrier has
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been detected and completes <tt/getty/'s open of the port. <tt/getty/
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sends a <tt/login:/ prompt at the specified initial line speed.
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<tt/getty/ watches to see if legitimate characters are received, and,
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in a typical configuration, if it finds junk (probably due to the
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modem's connection speed being different than <tt/getty/'s speed),
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<tt/getty/ tries adjusting the line speeds until it receives
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reasonable characters.
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We hope <tt/getty/ finds the correct speed and the user sees a
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<tt/login:/ prompt. After the user enters his/her login name,
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<tt/getty/ executes <tt>/usr/bin/login</tt>, which completes the login
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by asking for the user's password and then starting the user's shell.
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Let's dive into the configuration...
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<sect1><heading>Kernel Configuration</heading>
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<p>
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FreeBSD kernels typically come prepared to search for four serial
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ports, known in the PC-DOS world as <tt/COM1:/, <tt/COM2:/,
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<tt/COM3:/, and <tt/COM4:/. FreeBSD can presently also handle
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``dumb'' multiport serial interface cards, such as the Boca Board
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1008 and 2016 (please see the manual page <tt/sio(4)/ for kernel
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configuration information if you have a multiport serial card). The
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default kernel only looks for the standard COM ports, though.
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To see if your kernel recognizes any of your serial ports, watch for
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messages while the kernel is booting, or use the
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<tt>/sbin/dmesg</tt> command to replay the kernel's boot messages. In
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particular, look for messages that start with the characters <tt/sio/.
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Hint: to view just the messages that have the word <tt/sio/, use the
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command:
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<tscreen><verb>
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/sbin/dmesg | grep 'sio'
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</verb></tscreen>
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For example, on a system with four serial ports, these are the
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serial-port specific kernel boot messages:
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<tscreen><verb>
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sio0 at 0x3f8-0x3ff irq 4 on isa
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sio0: type 16550A
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sio1 at 0x2f8-0x2ff irq 3 on isa
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sio1: type 16550A
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sio2 at 0x3e8-0x3ef irq 5 on isa
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sio2: type 16550A
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sio3 at 0x2e8-0x2ef irq 9 on isa
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sio3: type 16550A
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</verb></tscreen>
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If your kernel does not recognize all of your serial ports, you will
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probably need to configure a custom FreeBSD kernel for your system.
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Please see the BSD System Manager's Manual chapter on ``Building
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Berkeley Kernels with Config'' [the source for which is in
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<tt>/usr/src/share/doc/smm</tt>] and ``FreeBSD Configuration
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Options'' [in <tt>/sys/conf/options</tt> and in
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<tt>/sys/<em>arch</em>/conf/options.<em>arch</em></tt>, with
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<em>arch</em> for example being <tt>i386</tt>] for more
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information on configuring and building kernels. You may have to
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unpack the kernel source distribution if have not installed the system
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sources already (<tt>srcdist/srcsys.??</tt> in FreeBSD 1.1,
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<tt>srcdist/sys.??</tt> in FreeBSD 1.1.5.1, or the entire source
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distribution in FreeBSD 2.0) to be able to configure and build
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kernels.
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Create a kernel configuration file for your system (if you have not
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already) by <tt/cd/ing to <tt>/sys/i386/conf</tt>. Then, if you are
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creating a new custom configuration file, copy the file GENERICAH (or
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GENERICBT, if you have a BusTek SCSI controller on FreeBSD 1.x) to
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<em/YOURSYS/, where <em/YOURSYS/ is the name of your system, but in
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upper-case letters. Edit the file, and change the device lines:
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<tscreen><verb>
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device sio0 at isa? port "IO_COM1" tty irq 4 vector siointr
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device sio1 at isa? port "IO_COM2" tty irq 3 vector siointr
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device sio2 at isa? port "IO_COM3" tty irq 5 vector siointr
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device sio3 at isa? port "IO_COM4" tty irq 9 vector siointr
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</verb></tscreen>
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You can comment-out or completely remove lines for devices you do not
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have. If you have a multiport serial board, such as the Boca Board
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BB2016, please see the <tt/sio(4)/ man page for complete information
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on how to write configuration lines for multiport boards. Be careful
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if you are using a configuration file that was previously used for a
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different version of FreeBSD because the device flags have changed
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between versions.
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Note that <tt/port "IO_COM1"/ is a substitution for <tt/port 0x3f8/,
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<tt/IO_COM2/ is <tt/0x2f8/, <tt/IO_COM3/ is <tt/0x3e8/, and
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<tt/IO_COM4/ is <tt/0x2e8/, which are fairly common port addresses for
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their respective serial ports; interrupts 4, 3, 5, and 9 are fairly
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common interrupt request lines. Also note that regular serial ports
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<bf>cannot</bf> share interrupts on ISA-bus PCs (multiport boards have
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on-board electronics that allow all the 16550A's on the board to share
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one or two interrupt request lines).
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When you are finished adjusting the kernel configuration file, use the
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program <tt/config/ as documented in ``Building Berkeley Kernels with
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Config'' and the <tt/config(8)/ manual page to prepare a kernel
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building directory, then build, install, and test the new kernel.
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<sect1><heading>Device Special Files</heading>
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<p>
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Most devices in the kernel are accessed through ``device special
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files'', which are located in the <tt>/dev</tt> directory. The
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<tt/sio/ devices are accessed through the <tt>/dev/ttyd?</tt>
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(dial-in) and <tt>/dev/cua0?</tt> (call-out) devices. On FreeBSD
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version 1.1.5 and higher, there are also initialization devices
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(<tt>/dev/ttyid?</tt> and <tt>/dev/cuai0?</tt>) and locking devices
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(<tt>/dev/ttyld?</tt> and <tt>/dev/cual0?</tt>). The initialization
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devices are used to initialize communications port parameters each
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time a port is opened, such as <tt>crtscts</tt> for modems which use
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<tt>CTS/RTS</tt> signaling for flow control. The locking devices are
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used to lock flags on ports to prevent users or programs changing
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certain parameters; see the manual pages <tt/termios(4)/, <tt/sio(4)/,
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and <tt/stty(1)/ for information on the terminal settings, locking
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& initializing devices, and setting terminal options,
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respectively.
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<sect2><heading>Making Device Special Files</heading>
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<p>
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A shell script called <tt/MAKEDEV/ in the <tt>/dev</tt> directory
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manages the device special files. (The manual page for
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<tt/MAKEDEV(8)/ on FreeBSD 1.1.5 is fairly bogus in its discussion of
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<tt/COM/ ports, so ignore it.) To use <tt/MAKEDEV/ to make dialup
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device special files for <tt/COM1:/ (port 0), <tt/cd/ to <tt>/dev</tt>
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and issue the command <tt/MAKEDEV ttyd0/. Likewise, to make dialup
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device special files for <tt/COM2:/ (port 1), use <tt/MAKEDEV ttyd1/.
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<tt/MAKDEV/ not only creates the <tt>/dev/ttyd?</tt> device special
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files, but also creates the <tt>/dev/cua0?</tt> (and all of the
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initializing and locking special files under FreeBSD 1.1.5 and up) and
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removes the hardwired terminal special file <tt>/dev/tty0?</tt>, if it
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exists.
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After making new device special files, be sure to check the
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permissions on the files (especially the <tt>/dev/cua*</tt> files) to
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make sure that only users who should have access to those device
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special files can read & write on them - you probably do not want
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to allow your average user to use your modems to dialout. The default
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permissions on the <tt>/dev/cua*</tt> files should be sufficient:
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<tscreen><verb>
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crw-rw---- 1 uucp dialer 28, 129 Feb 15 14:38 /dev/cua01
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crw-rw---- 1 uucp dialer 28, 161 Feb 15 14:38 /dev/cuai01
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crw-rw---- 1 uucp dialer 28, 193 Feb 15 14:38 /dev/cual01
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</verb></tscreen>
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These permissions allow the user <tt/uucp/ and users in the group
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<tt/dialer/ to use the call-out devices.
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<sect1><heading>Configuration Files</heading>
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<p>
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There are three system configuration files in the <tt>/etc</tt>
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directory that yo will probably need to edit to allow dialup access to
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your FreeBSD system. The first, <tt>/etc/gettytab</tt>, contains
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configuration information for the <tt>/usr/libexec/getty</tt> daemon.
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Second, <tt>/etc/ttys</tt> holds information that tells
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<tt>/sbin/init</tt> what <tt/tty/ devices should have <tt/getty/
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processes running on them. Lastly, you can place port initialization
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commands in the <tt>/etc/rc.serial</tt> script if you have FreeBSD
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1.1.5.1 or higher; otherwise, you can initialize ports in the
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<tt>/etc/rc.local</tt> script.
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There are two schools of thought regarding dialup modems on UNIX. One
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group likes to configure their modems and system so that no matter at
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what speed a remote user dials in, the local computer-to-modem RS-232
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interface runs at a locked speed. The benefit of this configuration
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is that the remote user always sees a system login prompt immediately.
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The downside is that the system does not know what a user's true data
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rate is, so full-screen programs like Emacs will not adjust their
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screen-painting methods to make their response better for slower
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connections.
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The other school configures their modems' RS-232 interface to vary its
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speed based on the remote user's connection speed. For example,
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V.32bis (14.4 Kbps) connections to the modem might make the modem run
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its RS-232 interface at 19.2 Kbps, while 2400 bps connections make the
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modem's RS-232 interface run at 2400 bps. Because <tt/getty/ does not
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understand any particular modem's connection speed reporting,
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<tt/getty/ gives a <tt/login:/ message at an initial speed and watches
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the characters that come back in response. If the user sees junk,
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it is assumed that they know they should press the
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<tt><Enter></tt> key until they see a recognizable prompt. If
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the data rates do not match, <tt/getty/ sees anything the user types as
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``junk'', tries going to the next speed and gives the <tt/login:/
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prompt again. This procedure can continue ad nauseum, but normally
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only takes a keystroke or two before the user sees a good prompt.
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Obviously, this login sequence does not look as clean as the former
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``locked-speed'' method, but a user on a low-speed connection should
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receive better interactive response from full-screen programs.
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The author will try to give balanced configuration information, but is
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biased towards having the modem's data rate follow the connection
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rate.
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<sect2><heading>/etc/gettytab</heading>
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<p>
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<tt>/etc/gettytab</tt> is a <tt/termcap(5)/-style file of
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configuration information for <tt/getty(8)/. Please see the
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<tt/gettytab(4)/ manual page for complete information on the format of
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the file and the list of capabilities.
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<sect3><heading>Locked-Speed Config</heading>
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<p>
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If you are locking your modem's data communications rate at a
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particular speed, you probably will not need to make any changes to
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<tt>/etc/gettytab</tt>.
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<sect3><heading>Matching-Speed Config</heading>
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<p>
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You will need to setup an entry in <tt>/etc/gettytab</tt> to give
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<tt/getty/ information about the speeds you wish to use for your
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modem. If you have a 2400 bps modem, you can probably use the
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existing <tt/D2400/ entry. This entry already exists in the FreeBSD
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1.1.5.1 <tt/gettytab/ file, so you do not need to add it unless it is
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missing under your version of FreeBSD:
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<tscreen><verb>
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#
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# Fast dialup terminals, 2400/1200/300 rotary (can start either way)
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#
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D2400|d2400|Fast-Dial-2400:\
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:nx=D1200:tc=2400-baud:
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3|D1200|Fast-Dial-1200:\
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:nx=D300:tc=1200-baud:
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5|D300|Fast-Dial-300:\
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:nx=D2400:tc=300-baud:
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</verb></tscreen>
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If you have a higher speed modem, you will probably need to add an entry
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in <tt>/etc/gettytab</tt>; here is an entry you could use for a 14.4
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Kbps modem with a top interface speed of 19.2 Kpbs:
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<tscreen><verb>
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#
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# Additions for a V.32bis Modem
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#
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um|V300|High Speed Modem at 300,8-bit:\
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:nx=V19200:tc=std.300:
|
|
un|V1200|High Speed Modem at 1200,8-bit:\
|
|
:nx=V300:tc=std.1200:
|
|
uo|V2400|High Speed Modem at 2400,8-bit:\
|
|
:nx=V1200:tc=std.2400:
|
|
up|V9600|High Speed Modem at 9600,8-bit:\
|
|
:nx=V2400:tc=std.9600:
|
|
uq|V19200|High Speed Modem at 19200,8-bit:\
|
|
:nx=V9600:tc=std.19200:
|
|
</verb></tscreen>
|
|
|
|
On FreeBSD 1.1.5 and later, this will result in 8-bit, no parity
|
|
connections. Under FreeBSD 1.1, add <tt/:np:/ parameters to the
|
|
<tt>std.<em/xxx/</tt> entries at the top of the file for 8 bits, no
|
|
parity; otherwise, the default is 7 bits, even parity.
|
|
|
|
The example above starts the communications rate at 19.2 Kbps (for a
|
|
V.32bis connection), then cycles through 9600 bps (for V.32), 2400
|
|
bps, 1200 bps, 300 bps, and back to 19.2 Kbps. Communications rate
|
|
cycling is implemented with the <tt/nx=/ (<bf/next table/) capability.
|
|
Each of the lines uses a <tt/tc=/ (<bf/table continuation/) entry to
|
|
pick up the rest of the ``standard'' settings for a particular data
|
|
rate.
|
|
|
|
If you have a 28.8 Kbps modem and/or you want to take advantage of
|
|
compression on a 14.4 Kbps modem, you need to use a higher
|
|
communications rate than 19.2 Kbps. Here is an example of a
|
|
<tt/gettytab/ entry starting a 57.6 Kpbs:
|
|
|
|
<tscreen><verb>
|
|
#
|
|
# Additions for a V.32bis or V.34 Modem
|
|
# Starting at 57.6 Kpbs
|
|
#
|
|
vm|VH300|Very High Speed Modem at 300,8-bit:\
|
|
:nx=VH57600:tc=std.300:
|
|
vn|VH1200|Very High Speed Modem at 1200,8-bit:\
|
|
:nx=VH300:tc=std.1200:
|
|
vo|VH2400|Very High Speed Modem at 2400,8-bit:\
|
|
:nx=VH1200:tc=std.2400:
|
|
vp|VH9600|Very High Speed Modem at 9600,8-bit:\
|
|
:nx=VH2400:tc=std.9600:
|
|
vq|VH57600|Very High Speed Modem at 57600,8-bit:\
|
|
:nx=VH9600:tc=std.57600:
|
|
</verb></tscreen>
|
|
|
|
If you have a slow CPU or a heavily loaded system and you dobnot have
|
|
16550A-based serial ports, you may receive sio ``silo'' errors at 57.6
|
|
Kbps.
|
|
|
|
<sect2><heading>/etc/ttys<label id="dialup:ttys"></heading>
|
|
<p>
|
|
|
|
<tt>/etc/ttys</tt> is the list of <tt/ttys/ for <tt/init/ to monitor.
|
|
<tt>/etc/ttys</tt> also provides security information to <tt/login/
|
|
(user <tt/root/ may only login on ttys marked <tt/secure/). See the
|
|
manual page for <tt/ttys(5)/ for more information.
|
|
|
|
You will need to either modify existing lines in <tt>/etc/ttys</tt> or
|
|
add new lines to make <tt/init/ run <tt/getty/ processes automatically
|
|
on your new dialup ports. The general format of the line will be the
|
|
same, whether you are using a locked-speed or matching-speed
|
|
configuration:
|
|
|
|
<tscreen><verb>
|
|
ttyd0 "/usr/libexec/getty xxx" dialup on
|
|
</verb></tscreen>
|
|
|
|
The first item in the above line is the device special file for this
|
|
entry - <tt/ttyd0/ means <tt>/dev/ttyd0</tt> is the file that this
|
|
<tt/getty/ will be watching. The second item, <tt>"/usr/libexec/getty
|
|
<em/xxx/"</tt> (<em/xxx/ will be replaced by the initial <tt/gettytab/
|
|
capability) is the process <tt/init/ will run on the device. The
|
|
third item, <tt/dialup/, is the default terminal type. The fourth
|
|
parameter, <tt/on/, indicates to <tt/init/ that the line is
|
|
operational. There can be a fifth parameter, <tt>secure</tt>, but it
|
|
should only be used for terminals which are physically secure (such as
|
|
the system console).
|
|
|
|
The default terminal type (<tt/dialup/ in the example above) may
|
|
depend on local preferences. <tt/dialup/ is the traditional default
|
|
terminal type on dialup lines so that users may customize their login
|
|
scripts to notice when the terminal is <tt/dialup/ and automatically
|
|
adjust their terminal type. However, the author finds it easier at
|
|
his site to specify <tt/vt102/ as the default terminal type, since the
|
|
users just use VT102 emulation on their remote systems.
|
|
|
|
After you have made changes to <tt>/etc/ttys</tt>, you may send the
|
|
<tt/init/ process a <tt/HUP/ signal to re-read the file. You can use
|
|
the command
|
|
|
|
<tscreen><verb>
|
|
kill -1 1
|
|
</verb></tscreen>
|
|
|
|
to send the signal. If this is your first time setting up the system,
|
|
though, you may want to wait until your modem(s) are properly
|
|
configured and connected before signaling <tt/init/.
|
|
|
|
<sect3><heading>Locked-Speed Config</heading>
|
|
<p>
|
|
|
|
For a locked-speed configuration, your <tt/ttys/ entry needs to
|
|
have a fixed-speed entry provided to <tt/getty/. For a modem whose
|
|
port speed is locked at 19.2 Kbps, the <tt/ttys/ entry might look like
|
|
this:
|
|
|
|
<tscreen><verb>
|
|
ttyd0 "/usr/libexec/getty std.19200" dialup on
|
|
</verb></tscreen>
|
|
|
|
If your modem is locked at a different data rate, substitute the
|
|
appropriate name for the <tt>std.<em/speed/</tt> entry for
|
|
<tt/std.19200/ from <tt>/etc/gettytab</tt> for your modem's data rate.
|
|
|
|
<sect3><heading>Matching-Speed Config</heading>
|
|
<p>
|
|
|
|
In a matching-speed configuration, your <tt/ttys/ entry needs to
|
|
reference the appropriate beginning ``auto-baud'' (sic) entry in
|
|
<tt>/etc/gettytab</tt>. For example, if you added the above suggested
|
|
entry for a matching-speed modem that starts at 19.2 Kbps (the
|
|
<tt/gettytab/ entry containing the <tt/V19200/ starting point), your
|
|
<tt/ttys/ entry might look like this:
|
|
|
|
<tscreen><verb>
|
|
ttyd0 "/usr/libexec/getty V19200" dialup on
|
|
</verb></tscreen>
|
|
|
|
<sect2><heading>/etc/rc.serial or /etc/rc.local</heading>
|
|
<p>
|
|
|
|
High-speed modems, like V.32, V.32bis, and V.34 modems, need to use
|
|
hardware (<tt>RTS/CTS</tt>) flow control. You can add <tt/stty/
|
|
commands to <tt>/etc/rc.serial</tt> on FreeBSD 1.1.5.1 and up, or
|
|
<tt>/etc/rc.local</tt> on FreeBSD 1.1, to set the hardware flow
|
|
control flag in the FreeBSD kernel for the modem ports.
|
|
|
|
For example, on a sample FreeBSD 1.1.5.1 system,
|
|
<tt>/etc/rc.serial</tt> reads:
|
|
|
|
<tscreen><verb>
|
|
#!/bin/sh
|
|
#
|
|
# Serial port initial configuration
|
|
|
|
stty -f /dev/ttyid1 crtscts
|
|
stty -f /dev/cuai01 crtscts
|
|
</verb></tscreen>
|
|
|
|
which sets the <tt/termios/ flag <tt/crtscts/ on serial port #1's
|
|
(<tt/COM2:/) dialin and dialout initialization devices.
|
|
|
|
On an old FreeBSD 1.1 system, these entries were added to
|
|
/etc/rc.local to set the <tt/crtscts/ flag on the devices:
|
|
|
|
<tscreen><verb>
|
|
# Set serial ports to use RTS/CTS flow control
|
|
stty -f /dev/ttyd0 crtscts
|
|
stty -f /dev/ttyd1 crtscts
|
|
stty -f /dev/ttyd2 crtscts
|
|
stty -f /dev/ttyd3 crtscts
|
|
</verb></tscreen>
|
|
|
|
Since there is no initialization device special file on FreeBSD
|
|
1.1, one has to just set the flags on the sole device special file and
|
|
hope the flags aren't cleared by a miscreant.
|
|
|
|
<sect1><heading>Modem Settings</heading>
|
|
<p>
|
|
|
|
If you have a modem whose parameters may be permanently set in
|
|
non-volatile RAM, you will need to use a terminal program (such as Telix
|
|
under PC-DOS or <tt/tip/ under FreeBSD) to set the parameters.
|
|
Connect to the modem using the same communications speed as the
|
|
initial speed <tt/getty/ will use and configure the modem's
|
|
non-volatile RAM to match these requirements:
|
|
|
|
<itemize>
|
|
|
|
<item> <tt/CD/ asserted when connected
|
|
|
|
<item> <tt/DTR/ asserted for operation; dropping DTR hangs up line
|
|
& resets modem
|
|
|
|
<item> <tt/CTS/ transmitted data flow control
|
|
|
|
<item> Disable <tt>XON/XOFF</tt> flow control
|
|
|
|
<item> <tt/RTS/ received data flow control
|
|
|
|
<item> Quiet mode (no result codes)
|
|
|
|
<item> No command echo
|
|
|
|
</itemize>
|
|
|
|
Please read the documentation for your modem to find out what commands
|
|
and/or DIP switch settings you need to give it.
|
|
|
|
For example, to set the above parameters on a USRobotics Sportster
|
|
14,400 external modem, one could give these commands to the modem:
|
|
|
|
<tscreen><verb>
|
|
ATZ
|
|
AT&C1&D2&H1&I0&R2&W
|
|
</verb></tscreen>
|
|
|
|
You might also want to take this opportunity to adjust other settings
|
|
in the modem, such as whether it will use V.42bis and/or MNP5
|
|
compression.
|
|
|
|
The USR Sportster 14,400 external modem also has some DIP switches
|
|
that need to be set; for other modems, perhaps you can use these
|
|
settings as an example:
|
|
|
|
<itemize>
|
|
|
|
<item> Switch 1: UP - DTR Normal
|
|
|
|
<item> Switch 2: Do not care (Verbal Result Codes/Numeric Result Codes)
|
|
|
|
<item> Switch 3: UP - Suppress Result Codes
|
|
|
|
<item> Switch 4: DOWN - No echo, offline commands
|
|
|
|
<item> Switch 5: UP - Auto Answer
|
|
|
|
<item> Switch 6: UP - Carrier Detect Normal
|
|
|
|
<item> Switch 7: UP - Load NVRAM Defaults
|
|
|
|
<item> Switch 8: Do not care (Smart Mode/Dumb Mode)
|
|
|
|
</itemize>
|
|
|
|
Result codes should be disabled/suppressed for dialup modems to avoid
|
|
problems that can occur if <tt/getty/ mistakenly gives a <tt/login:/
|
|
prompt to a modem that is in command mode and the modem echoes the
|
|
command or returns a result code. I have heard this sequence can result
|
|
in a extended, silly conversation between <tt/getty/ and the modem.
|
|
|
|
<sect2><heading>Locked-speed Config</heading>
|
|
<p>
|
|
|
|
For a locked-speed configuration, you will need to configure the modem
|
|
to maintain a constant modem-to-computer data rate independent of the
|
|
communications rate. On a USR Sportster 14,400 external modem, these
|
|
commands will lock the modem-to-computer data rate at the speed used
|
|
to issue the commands:
|
|
|
|
<tscreen><verb>
|
|
ATZ
|
|
AT&B1&W
|
|
</verb></tscreen>
|
|
|
|
<sect2><heading>Matching-speed Config</heading>
|
|
<p>
|
|
|
|
For a variable-speed configuration, you will need to configure your
|
|
modem to adjust its serial port data rate to match the incoming call
|
|
rate. On a USR Sportster 14,400 external modem, these commands will
|
|
lock the modem's error-corrected data rate to the speed used to issue
|
|
the commands, but allow the serial port rate to vary for
|
|
non-error-corrected connections:
|
|
|
|
<tscreen><verb>
|
|
ATZ
|
|
AT&B2&W
|
|
</verb></tscreen>
|
|
|
|
<sect2><heading>Checking the Modem's Configuration</heading>
|
|
<p>
|
|
|
|
Most high-speed modems provide commands to view the modem's current
|
|
operating parameters in a somewhat human-readable fashion. On the USR
|
|
Sportster 14,400 external modems, the command <tt/ATI5/ displays the
|
|
settings that are stored in the non-volatile RAM. To see the true
|
|
operating parameters of the modem (as influenced by the USR's DIP
|
|
switch settings), use the commands <tt/ATZ/ and then <tt/ATI4/.
|
|
|
|
If you have a different brand of modem, check your modem's manual to
|
|
see how to double-check your modem's configuration parameters.
|
|
|
|
<sect1><heading>Troubleshooting</heading>
|
|
<p>
|
|
|
|
Here are a few steps you can follow to check out the dialup modem on
|
|
your system.
|
|
|
|
<sect2><heading>Checking out the FreeBSD system</heading>
|
|
<p>
|
|
|
|
Hook up your modem to your FreeBSD system, boot the system, and, if
|
|
your modem has status indication lights, watch to see whether the
|
|
modem's <tt/DTR/ indicator lights when the <tt/login:/ prompt appears
|
|
on the system's console - if it lights up, that should mean that
|
|
FreeBSD has started a <tt/getty/ process on the appropriate
|
|
communications port and is waiting for the modem to accept a call.
|
|
|
|
If the <tt/DTR/ indicator doesn't light, login to the FreeBSD system
|
|
through the console and issue a <tt/ps ax/ to see if FreeBSD is trying
|
|
to run a <tt/getty/ process on the correct port. You should see a
|
|
lines like this among the processes displayed:
|
|
|
|
<tscreen><verb>
|
|
114 ?? I 0:00.10 /usr/libexec/getty V19200 ttyd0
|
|
115 ?? I 0:00.10 /usr/libexec/getty V19200 ttyd1
|
|
</verb></tscreen>
|
|
|
|
If you see something different, like this:
|
|
|
|
<tscreen><verb>
|
|
114 d0 I 0:00.10 /usr/libexec/getty V19200 ttyd0
|
|
^^
|
|
</verb></tscreen>
|
|
|
|
and the modem has not accepted a call yet, this means that <tt/getty/
|
|
has completed its open on the communications port. This could
|
|
indicate a problem with the cabling or a mis-configured modem, because
|
|
<tt/getty/ should not be able to open the communications port until
|
|
<tt/CD/ (carrier detect) has been asserted by the modem.
|
|
|
|
If you do not see any <tt/getty/ processes waiting to open the desired
|
|
<tt/ttyd?/ port, double-check your entries in <tt>/etc/ttys</tt> to
|
|
see if there are any mistakes there. Also, check the log file
|
|
<tt>/var/log/messages</tt> to see if there are any log messages from
|
|
<tt/init/ or <tt/getty/ regarding any problems. If there are any
|
|
messages, triple-check the configuration files <tt>/etc/ttys</tt> and
|
|
<tt>/etc/gettytab</tt>, as well as the appropriate device special
|
|
files <tt>/dev/ttyd?</tt>, for any mistakes, missing entries, or
|
|
missing device special files.
|
|
|
|
<sect2><heading>Try Dialing In</heading>
|
|
<p>
|
|
|
|
Try dialing into the system; be sure to use 8 bits, no parity, 1 stop
|
|
bit on the remote system. If you do not get a prompt right away, or
|
|
get garbage, try pressing <tt><Enter></tt> about once per
|
|
second. If you still do not see a <tt/login:/ prompt after a while,
|
|
try sending a <tt>BREAK</tt>. If you are using a high-speed modem to
|
|
do the dialing, try dialing again after locking the dialing modem's
|
|
interface speed (via <tt>AT&B1</tt> on a USR Sportster, for
|
|
example).
|
|
|
|
If you still cannot get a <tt/login:/ prompt, check
|
|
<tt>/etc/gettytab</tt> again and double-check that
|
|
|
|
<itemize>
|
|
<item> The initial capability name specified in <tt>/etc/ttys</tt> for
|
|
the line matches a name of a capability in <tt>/etc/gettytab</tt>
|
|
|
|
<item> Each <tt/nx=/ entry matches another <tt/gettytab/ capability
|
|
name
|
|
|
|
<item> Each <tt/tc=/ entry matches another <tt/gettytab/ capability
|
|
name
|
|
|
|
</itemize>
|
|
|
|
If you dial but the modem on the FreeBSD system will not answer, make
|
|
sure that the modem is configured to answer the phone when <tt/DTR/ is
|
|
asserted. If the modem seems to be configured correctly, verify that
|
|
the <tt/DTR/ line is asserted by checking the modem's indicator lights
|
|
(if it has any).
|
|
|
|
If you have gone over everything several times and it still does not work,
|
|
take a break and come back to it later. If it still does not work,
|
|
perhaps you can send an electronic mail message to the &a.questions
|
|
describing your modem and youer problem, and the good folks on the list will
|
|
try to help.
|
|
|
|
<sect1><heading>Acknowledgments</heading>
|
|
<p>
|
|
|
|
Thanks to these people for comments and advice:
|
|
|
|
<descrip>
|
|
|
|
<tag>&a.kelly</tag> for a number of good suggestions
|
|
|
|
</descrip>
|
|
|
|
|