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     The FreeBSD Documentation Project

     $FreeBSD$
     Original revision: 1.108
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<chapter id="serialcomms">
  <title>Serial Communications</title>

  <sect1 id="serial-synopsis">
    <title>Synopsis</title>

    <indexterm><primary>serial communications</primary></indexterm>
    <para>&unix; has always had support for serial communications.  In fact,
      the very first &unix; machines relied on serial lines for user input
      and output.  Things have changed a lot from the days when the average
      <quote>terminal</quote> consisted of a 10-character-per-second serial
      printer and a keyboard.  This chapter will cover some of the ways in
      which FreeBSD uses serial communications.</para>

    <para>After reading this chapter, you will know:</para>
    <itemizedlist>
      <listitem><para>How to connect terminals to your FreeBSD
	  system.</para></listitem>
      <listitem><para>How to use a modem to dial out to remote
	  hosts.</para></listitem>
      <listitem><para>How to allow remote users to login to your
	  system with a modem.</para></listitem>
      <listitem><para>How to boot your system from a serial
	  console.</para></listitem>
    </itemizedlist>

    <para>Before reading this chapter, you should:</para>
    <itemizedlist>
      <listitem><para>Know how to configure and install a new kernel (<xref
        linkend="kernelconfig"/>).</para></listitem>
      <listitem><para>Understand &unix; permissions and processes (<xref linkend="basics"/>).</para></listitem>
      <listitem><para>Have access to the technical manual for the
        serial hardware (modem or multi-port card) that you would like
        to use with FreeBSD.</para></listitem>
    </itemizedlist>
  </sect1>

  <sect1 id="serial">
    <title>Introduction</title>

    <!-- XXX Write me! -->

    <sect2 id="serial-terminology">
      <title>Terminology</title>

      <variablelist>
        <indexterm><primary>bits-per-second</primary></indexterm>
	<varlistentry>
	  <term>bps</term>
	  <listitem>
	    <para>Bits per Second &mdash; the rate at which data is
	      transmitted</para>
	  </listitem>
	</varlistentry>

	<varlistentry>
	  <term>DTE</term>
	  <listitem>
	    <indexterm><primary>DTE</primary></indexterm>

	    <para>Data Terminal Equipment &mdash; for example, your
	      computer</para>
	  </listitem>
	</varlistentry>

	<varlistentry>
	  <term>DCE</term>
	  <listitem>
	    <indexterm><primary>DCE</primary></indexterm>

	    <para>Data Communications Equipment &mdash;  your modem</para>
	  </listitem>
	</varlistentry>

	<varlistentry>
	  <term>RS-232</term>
	  <listitem>
	    <indexterm><primary>RS-232C cables</primary></indexterm>

	    <para>EIA standard for hardware serial communications</para>
	  </listitem>
	</varlistentry>
      </variablelist>

      <para>When talking about communications data rates, this section
	does not use the term <quote>baud</quote>.  Baud refers to the
	number of electrical state transitions that may be made in a
	period of time, while <quote>bps</quote> (bits per second) is
	the <emphasis>correct</emphasis> term to use (at least it does not
	seem to bother the curmudgeons quite as much).</para>
    </sect2>

    <sect2 id="serial-cables-ports">
      <title>Cables and Ports</title>

      <para>To connect a modem or terminal to your FreeBSD system, you
	will need a serial port on your computer and the proper cable to connect
	to your serial device.  If you are already familiar with your
	hardware and the cable it requires, you can safely skip this
	section.</para>

      <sect3 id="term-cables">
	<title>Cables</title>

	<para>There are several different kinds of serial cables.  The
	  two most common types for our purposes are null-modem cables
	  and standard (<quote>straight</quote>) RS-232 cables.  The documentation
	  for your hardware should describe the type of cable
	  required.</para>

	<sect4 id="term-cables-null">
	  <title>Null-modem Cables</title>

	  <indexterm>
	    <primary>null-modem cable</primary>
	  </indexterm>
	  <para>A null-modem cable passes some signals, such as <quote>Signal
	    Ground</quote>, straight through, but switches other signals.  For
	    example, the <quote>Transmitted Data</quote> pin on one end goes to the
	    <quote>Received Data</quote> pin on the other end.</para>

	  <para>You can also construct your own null-modem cable for use with
	    terminals (e.g., for quality purposes).  This table shows the RS-232C
	    <link linkend="serialcomms-signal-names">signals</link> and the pin
	    numbers on a DB-25 connector.  Note that the standard also calls for a
	    straight-through pin 1 to pin 1 <emphasis>Protective Ground</emphasis>
	    line, but it is often omitted.  Some terminals work OK using only
	    pins 2, 3 and 7, while others require different configurations than
	    the examples shown below.</para>

	  <table frame="none" pgwide="1">
	    <title>DB-25 to DB-25 Null-Modem Cable</title>

	    <tgroup cols="5">
	      <thead>
		<row>
		  <entry align="left">Signal</entry>
		  <entry align="left">Pin #</entry>
		  <entry></entry>
		  <entry align="left">Pin #</entry>
		  <entry align="left">Signal</entry>
		</row>
	      </thead>

	      <tbody>
		<row>
		  <entry>SG</entry>
		  <entry>7</entry>
		  <entry>connects to</entry>
		  <entry>7</entry>
		  <entry>SG</entry>
		</row>

		<row>
		  <entry>TD</entry>
		  <entry>2</entry>
		  <entry>connects to</entry>
		  <entry>3</entry>
		  <entry>RD</entry>
		</row>

		<row>
		  <entry>RD</entry>
		  <entry>3</entry>
		  <entry>connects to</entry>
		  <entry>2</entry>
		  <entry>TD</entry>
		</row>

		<row>
		  <entry>RTS</entry>
		  <entry>4</entry>
		  <entry>connects to</entry>
		  <entry>5</entry>
		  <entry>CTS</entry>
		</row>

		<row>
		  <entry>CTS</entry>
		  <entry>5</entry>
		  <entry>connects to</entry>
		  <entry>4</entry>
		  <entry>RTS</entry>
		</row>

		<row>
		  <entry>DTR</entry>
		  <entry>20</entry>
		  <entry>connects to</entry>
		  <entry>6</entry>
		  <entry>DSR</entry>
		</row>

		<row>
		  <entry>DTR</entry>
		  <entry>20</entry>
		  <entry>connects to</entry>
		  <entry>8</entry>
		  <entry>DCD</entry>
		</row>

		<row>
		  <entry>DSR</entry>
		  <entry>6</entry>
		  <entry>connects to</entry>
		  <entry>20</entry>
		  <entry>DTR</entry>
		</row>

		<row>
		  <entry>DCD</entry>
		  <entry>8</entry>
		  <entry>connects to</entry>
		  <entry>20</entry>
		  <entry>DTR</entry>
		</row>
	      </tbody>
	    </tgroup>
	  </table>

	  <para>Here are two other schemes more common nowadays.</para>

          <table frame="none" pgwide="1">
            <title>DB-9 to DB-9 Null-Modem Cable</title>

            <tgroup cols="5">
              <thead>
                <row>
                  <entry align="left">Signal</entry>
                  <entry align="left">Pin #</entry>
                  <entry></entry>
                  <entry align="left">Pin #</entry>
                  <entry align="left">Signal</entry>
                </row>
              </thead>

              <tbody>
                <row>
                  <entry>RD</entry>
                  <entry>2</entry>
                  <entry>connects to</entry>
                  <entry>3</entry>
                  <entry>TD</entry>
                </row>

                <row>
                  <entry>TD</entry>
                  <entry>3</entry>
                  <entry>connects to</entry>
                  <entry>2</entry>
                  <entry>RD</entry>
                </row>

                <row>
                  <entry>DTR</entry>
                  <entry>4</entry>
                  <entry>connects to</entry>
                  <entry>6</entry>
                  <entry>DSR</entry>
                </row>

                <row>
                  <entry>DTR</entry>
                  <entry>4</entry>
                  <entry>connects to</entry>
                  <entry>1</entry>
                  <entry>DCD</entry>
                </row>

                <row>
                  <entry>SG</entry>
                  <entry>5</entry>
                  <entry>connects to</entry>
                  <entry>5</entry>
                  <entry>SG</entry>
                </row>

                <row>
                  <entry>DSR</entry>
                  <entry>6</entry>
                  <entry>connects to</entry>
                  <entry>4</entry>
                  <entry>DTR</entry>
                </row>

                <row>
                  <entry>DCD</entry>
                  <entry>1</entry>
                  <entry>connects to</entry>
                  <entry>4</entry>
                  <entry>DTR</entry>
                </row>

                <row>
                  <entry>RTS</entry>
                  <entry>7</entry>
                  <entry>connects to</entry>
                  <entry>8</entry>
                  <entry>CTS</entry>
                </row>

                <row>
                  <entry>CTS</entry>
                  <entry>8</entry>
                  <entry>connects to</entry>
                  <entry>7</entry>
                  <entry>RTS</entry>
                </row>
              </tbody>
            </tgroup>
          </table>

          <table frame="none" pgwide="1">
            <title>DB-9 to DB-25 Null-Modem Cable</title>

            <tgroup cols="5">
              <thead>
                <row>
                  <entry align="left">Signal</entry>
                  <entry align="left">Pin #</entry>
                  <entry></entry>
                  <entry align="left">Pin #</entry>
                  <entry align="left">Signal</entry>
                </row>
              </thead>

              <tbody>
                <row>
                  <entry>RD</entry>
                  <entry>2</entry>
                  <entry>connects to</entry>
                  <entry>2</entry>
                  <entry>TD</entry>
                </row>

                <row>
                  <entry>TD</entry>
                  <entry>3</entry>
                  <entry>connects to</entry>
                  <entry>3</entry>
                  <entry>RD</entry>
                </row>

                <row>
                  <entry>DTR</entry>
                  <entry>4</entry>
                  <entry>connects to</entry>
                  <entry>6</entry>
                  <entry>DSR</entry>
                </row>

                <row>
                  <entry>DTR</entry>
                  <entry>4</entry>
                  <entry>connects to</entry>
                  <entry>8</entry>
                  <entry>DCD</entry>
                </row>

                <row>
                  <entry>SG</entry>
                  <entry>5</entry>
                  <entry>connects to</entry>
                  <entry>7</entry>
                  <entry>SG</entry>
                </row>

                <row>
                  <entry>DSR</entry>
                  <entry>6</entry>
                  <entry>connects to</entry>
                  <entry>20</entry>
                  <entry>DTR</entry>
                </row>

                <row>
                  <entry>DCD</entry>
                  <entry>1</entry>
                  <entry>connects to</entry>
                  <entry>20</entry>
                  <entry>DTR</entry>
                </row>

                <row>
                  <entry>RTS</entry>
                  <entry>7</entry>
                  <entry>connects to</entry>
                  <entry>5</entry>
                  <entry>CTS</entry>
                </row>

                <row>
                  <entry>CTS</entry>
                  <entry>8</entry>
                  <entry>connects to</entry>
                  <entry>4</entry>
                  <entry>RTS</entry>
                </row>
              </tbody>
            </tgroup>
          </table>

	  <note>
	    <para>When one pin at one end connects to a pair of pins
	      at the other end, it is usually implemented with one short
	      wire between the pair of pins in their connector and a
	      long wire to the other single pin.</para>
	  </note>

	  <para>The above designs seems to be the most popular.  In another
	    variation (explained in the book <emphasis>RS-232 Made
	      Easy</emphasis>) SG connects to SG, TD connects to RD, RTS and
	    CTS connect to DCD, DTR connects to DSR, and vice-versa.</para>
	</sect4>

	<sect4 id="term-cables-std">
	  <title>Standard RS-232C Cables</title>
	  <indexterm><primary>RS-232C cables</primary></indexterm>

	  <para>A standard serial cable passes all of the RS-232C signals
	    straight through.  That is, the <quote>Transmitted Data</quote> pin on one
	    end of the cable goes to the <quote>Transmitted Data</quote> pin on the
	    other end. This is the type of cable to use to connect a modem to your
	    FreeBSD system, and is also appropriate for some
	    terminals.</para>
	</sect4>
      </sect3>

      <sect3 id="term-ports">
	<title>Ports</title>

	<para>Serial ports are the devices through which data is transferred
	  between the FreeBSD host computer and the terminal. This section
	  describes the kinds of ports that exist and how they are addressed
	  in FreeBSD.</para>

	<sect4 id="term-portkinds">
	  <title>Kinds of Ports</title>

	  <para>Several kinds of serial ports exist.  Before you purchase or
	    construct a cable, you need to make sure it will fit the ports on
	    your terminal and on the FreeBSD system.</para>

	  <para>Most terminals will have DB-25 ports.  Personal computers,
	    including PCs running FreeBSD, will have DB-25 or DB-9 ports. If you
	    have a multiport serial card for your PC, you may have RJ-12 or
	    RJ-45 ports.</para>

	  <para>See the documentation that accompanied the hardware for
	    specifications on the kind of port in use.  A visual inspection of
	    the port often works too.</para>
	</sect4>

	<sect4 id="term-portnames">
	  <title>Port Names</title>

	  <para>In FreeBSD, you access each serial port through an entry in
	    the <filename>/dev</filename> directory.  There are two different
	    kinds of entries:</para>

	  <itemizedlist>
	    <listitem>
	      <para>Call-in ports are named
		<filename>/dev/ttyd<replaceable>N</replaceable></filename>
		where <replaceable>N</replaceable> is the port number,
		starting from zero.  Generally, you use the call-in port for
		terminals.  Call-in ports require that the serial line assert
		the data carrier detect (DCD) signal to work correctly.</para>
	    </listitem>

	    <listitem>
	      <para>Call-out ports are named
		<filename>/dev/cuad<replaceable>N</replaceable></filename>.
		You usually do not use the call-out port for terminals, just
		for modems.  You may use the call-out port if the serial cable
		or the terminal does not support the carrier detect
		signal.</para>

	      <note><para>Call-out ports are named
		<filename>/dev/cuaa<replaceable>N</replaceable></filename> in
		&os;&nbsp;5.X and older.</para></note>
	    </listitem>
	  </itemizedlist>

	  <para>If you have connected a terminal to the first serial port
	    (<devicename>COM1</devicename> in &ms-dos;), then you will
	    use <filename>/dev/ttyd0</filename> to refer to the terminal.  If
	    the terminal is on the second serial port (also known as
	    <devicename>COM2</devicename>), use
	    <filename>/dev/ttyd1</filename>, and so forth.</para>

	</sect4>
      </sect3>
    </sect2>

    <sect2>
      <title>Kernel Configuration</title>

      <para>FreeBSD supports four serial ports by default.  In the
	&ms-dos; world, these are known as
	<devicename>COM1</devicename>,
	<devicename>COM2</devicename>,
	<devicename>COM3</devicename>, and
	<devicename>COM4</devicename>.  FreeBSD currently supports
	<quote>dumb</quote> multiport serial interface cards, such as
	the BocaBoard 1008 and 2016, as well as more
	intelligent multi-port cards such as those made by Digiboard
	and Stallion Technologies.  However, the default kernel only looks
	for the standard COM ports.</para>

      <para>To see if your kernel recognizes any of your serial ports, watch
	for messages while the kernel is booting, or use the
	<command>/sbin/dmesg</command> command to replay the kernel's boot
	messages.  In particular, look for messages that start with the
	characters <literal>sio</literal>.</para>

      <tip><para>To view just the messages that have the word
	<literal>sio</literal>, use the command:</para>

      <screen>&prompt.root; <userinput>/sbin/dmesg | grep 'sio'</userinput></screen>
      </tip>

      <para>For example, on a system with four serial ports, these are the
	serial-port specific kernel boot messages:</para>

      <screen>sio0 at 0x3f8-0x3ff irq 4 on isa
sio0: type 16550A
sio1 at 0x2f8-0x2ff irq 3 on isa
sio1: type 16550A
sio2 at 0x3e8-0x3ef irq 5 on isa
sio2: type 16550A
sio3 at 0x2e8-0x2ef irq 9 on isa
sio3: type 16550A</screen>

      <para>If your kernel does not recognize all of your serial
	ports, you will probably need to configure your kernel
	in the <filename>/boot/device.hints</filename> file.  You can
	also comment-out or completely remove lines for devices you do not
	have.</para>

      <para>On &os;&nbsp;4.X you have to edit your kernel configuration file.
	For detailed information on configuring your kernel, please see <xref
	linkend="kernelconfig"/>.  The relevant device lines would look like
	this:</para>

      <programlisting>device		sio0	at isa? port IO_COM1 irq 4
device		sio1	at isa? port IO_COM2 irq 3
device		sio2	at isa? port IO_COM3 irq 5
device		sio3	at isa? port IO_COM4 irq 9</programlisting>

      <para>Please refer to the &man.sio.4; manual page for
	more information on serial ports and multiport boards configuration.
	Be careful if you are using a configuration
	file that was previously used for a different version of
	FreeBSD because the device flags and the syntax have changed between
	versions.</para>

      <note>
	<para><literal>port IO_COM1</literal> is a substitution for
	  <literal>port 0x3f8</literal>, <literal>IO_COM2</literal> is
	  <literal>0x2f8</literal>, <literal>IO_COM3</literal> is
	  <literal>0x3e8</literal>, and <literal>IO_COM4</literal> is
	  <literal>0x2e8</literal>, which are fairly common port addresses for
	  their respective serial ports; interrupts 4, 3, 5, and 9 are fairly
	  common interrupt request lines.  Also note that regular serial ports
	  <emphasis>cannot</emphasis> share interrupts on ISA-bus PCs
	  (multiport boards have on-board electronics that allow all the
	  16550A's on the board to share one or two interrupt request
	  lines).</para>
      </note>

    </sect2>

    <sect2>
      <title>Device Special Files</title>

      <para>Most devices in the kernel are accessed through <quote>device
	special files</quote>, which are located in the
	<filename>/dev</filename> directory.  The <devicename>sio</devicename>
	devices are accessed through the
	<filename>/dev/ttyd<replaceable>N</replaceable></filename> (dial-in)
	and <filename>/dev/cuad<replaceable>N</replaceable></filename>
	(call-out) devices.  FreeBSD also provides initialization devices
	(<filename>/dev/ttyd<replaceable>N</replaceable>.init</filename> and
	<filename>/dev/cuad<replaceable>N</replaceable>.init</filename> on
	&os;&nbsp;6.X,
	<filename>/dev/ttyid<replaceable>N</replaceable></filename> and
	<filename>/dev/cuaid<replaceable>N</replaceable></filename> on
	&os;&nbsp;5.X and older) and
	locking devices
	(<filename>/dev/ttyd<replaceable>N</replaceable>.lock</filename> and
	<filename>/dev/cuad<replaceable>N</replaceable>.lock</filename> on
	&os;&nbsp;6.X,
	<filename>/dev/ttyld<replaceable>N</replaceable></filename> and
	<filename>/dev/cuald<replaceable>N</replaceable></filename> on
	&os;&nbsp;5.X and older).  The
	initialization devices are used to initialize communications port
	parameters each time a port is opened, such as
	<literal>crtscts</literal> for modems which use
	<literal>RTS/CTS</literal> signaling for flow control.  The locking
	devices are used to lock flags on ports to prevent users or programs
	changing certain parameters; see the manual pages &man.termios.4;,
	  &man.sio.4;, and &man.stty.1; for
	information on the terminal settings, locking and initializing
	devices, and setting terminal options, respectively.</para>

      <sect3>
	<title>Making Device Special Files</title>

	<note><para>FreeBSD&nbsp;5.0 includes the &man.devfs.5;
	  filesystem which automatically creates device nodes as
	  needed.  If you are running a version of FreeBSD with
	  <literal>devfs</literal> enabled then you can safely skip
	  this section.</para></note>

	<para>A shell script called <command>MAKEDEV</command> in the
	  <filename>/dev</filename> directory manages the device special
	  files.  To use <command>MAKEDEV</command> to make dial-up device
	  special files for <devicename>COM1</devicename> (port 0),
	  <command>cd</command> to <filename>/dev</filename> and issue the
	  command <command>MAKEDEV ttyd0</command>. Likewise, to make dial-up
	  device special files for <devicename>COM2</devicename> (port 1),
	  use <command>MAKEDEV ttyd1</command>.</para>

	<para><command>MAKEDEV</command> not only creates the
	  <filename>/dev/ttyd<replaceable>N</replaceable></filename> device
	  special files, but also the
	  <filename>/dev/cuaa<replaceable>N</replaceable></filename>,
	  <filename>/dev/cuaia<replaceable>N</replaceable></filename>,
	  <filename>/dev/cuala<replaceable>N</replaceable></filename>,
	  <filename>/dev/ttyld<replaceable>N</replaceable></filename>,
	  and
	  <filename>/dev/ttyid<replaceable>N</replaceable></filename>
	  nodes.</para>

	<para>After making new device special files, be sure to check the
	  permissions on the files (especially the
	  <filename>/dev/cua*</filename> files) to make sure that only users
	  who should have access to those device special files can read and
	  write on them &mdash; you probably do not want to allow your average
	  user to use your modems to dial-out.  The default permissions on the
	  <filename>/dev/cua*</filename> files should be sufficient:</para>

	<screen>crw-rw----    1 uucp     dialer    28, 129 Feb 15 14:38 /dev/cuaa1
crw-rw----    1 uucp     dialer    28, 161 Feb 15 14:38 /dev/cuaia1
crw-rw----    1 uucp     dialer    28, 193 Feb 15 14:38 /dev/cuala1</screen>

	<para>These permissions allow the user <username>uucp</username> and
	  users in the group <username>dialer</username> to use the call-out
	  devices.</para>
      </sect3>
    </sect2>


    <sect2 id="serial-hw-config">
      <title>Serial Port Configuration</title>

    <indexterm><primary><devicename>ttyd</devicename></primary></indexterm>
    <indexterm><primary><devicename>cuad</devicename></primary></indexterm>

    <para>The <devicename>ttyd<replaceable>N</replaceable></devicename> (or
      <devicename>cuad<replaceable>N</replaceable></devicename>) device is the
      regular device you will want to open for your applications.  When a
      process opens the device, it will have a default set of terminal I/O
      settings.  You can see these settings with the command</para>

    <screen>&prompt.root; <userinput>stty -a -f /dev/ttyd1</userinput></screen>

    <para>When you change the settings to this device, the settings are in
      effect until the device is closed.  When it is reopened, it goes back to
      the default set.  To make changes to the default set, you can open and
      adjust the settings of the <quote>initial state</quote> device. For
      example, to turn on <option>CLOCAL</option> mode, 8 bit communication,
      and <option>XON/XOFF</option> flow control by default for
      <devicename>ttyd5</devicename>, type:</para>

    <screen>&prompt.root; <userinput>stty -f /dev/ttyd5.init clocal cs8 ixon ixoff</userinput></screen>

    <indexterm>
      <primary>rc files</primary>
      <secondary><filename>rc.serial</filename></secondary>
    </indexterm>

    <para>System-wide initialization of the serial devices is
      controlled in <filename>/etc/rc.d/serial</filename>.  This file
      affects the default settings of serial devices.</para>

    <note>
      <para>On &os;&nbsp;4.X, system-wide initialization of the serial devices
	is controlled in <filename>/etc/rc.serial</filename>.</para>
    </note>

    <para>To prevent certain settings from being changed by an
      application, make adjustments to the <quote>lock state</quote>
      device.  For example, to lock the speed of
      <devicename>ttyd5</devicename> to 57600&nbsp;bps, type:</para>

    <screen>&prompt.root; <userinput>stty -f /dev/ttyd5.lock 57600</userinput></screen>

    <para>Now, an application that opens
      <devicename>ttyd5</devicename> and tries to change the speed of
      the port will be stuck with 57600&nbsp;bps.</para>

    <indexterm>
      <primary><command>MAKEDEV</command></primary>
    </indexterm>
    <para>Naturally, you should make the initial state and lock state devices
      writable only by the <username>root</username> account.</para>
    </sect2>
  </sect1>

  <sect1 id="term">
    <sect1info>
      <authorgroup>
        <author>
	  <firstname>Sean</firstname>
	  <surname>Kelly</surname>
	  <contrib>Contributed by </contrib>
	</author>
	<!-- 28 July 1996 -->
      </authorgroup>
    </sect1info>
    <title>Terminals</title>

    <indexterm><primary>terminals</primary></indexterm>

    <para>Terminals provide a convenient and low-cost way to access
      your FreeBSD system when you are not at the computer's console or on
      a connected network.  This section describes how to use terminals with
      FreeBSD.</para>

    <sect2 id="term-uses">
      <title>Uses and Types of Terminals</title>

      <para>The original &unix; systems did not have consoles.  Instead, people
	logged in and ran programs through terminals that were connected to
	the computer's serial ports.  It is quite similar to using a modem and
	terminal software to dial into a remote system to do text-only
	work.</para>

      <para>Today's PCs have consoles capable of high quality graphics, but
	the ability to establish a login session on a serial port still exists
	in nearly every &unix; style operating system today; FreeBSD is no
	exception.  By using a terminal attached to an unused serial port, you
	can log in and run any text program that you would normally run on the
	console or in an <command>xterm</command> window in the X Window
	System.</para>

      <para>For the business user, you can attach many terminals to a FreeBSD
	system and place them on your employees' desktops.  For a home user, a
	spare computer such as an older IBM PC or a &macintosh; can be a
	terminal wired into a more powerful computer running FreeBSD.  You can
	turn what might otherwise be a single-user computer into a powerful
	multiple user system.</para>

      <para>For FreeBSD, there are three kinds of terminals:</para>

      <itemizedlist>
	<listitem>
	  <para><link linkend="term-dumb">Dumb terminals</link></para>
	</listitem>

	<listitem>
	  <para><link linkend="term-pcs">PCs acting as terminals</link></para>
	</listitem>

	<listitem>
	  <para><link linkend="term-x">X terminals</link></para>
	</listitem>
      </itemizedlist>

      <para>The remaining subsections describe each kind.</para>

      <sect3 id="term-dumb">
	<title>Dumb Terminals</title>

	<para>Dumb terminals are specialized pieces of hardware that let you
	  connect to computers over serial lines.  They are called
	  <quote>dumb</quote> because they have only enough computational power
	  to display, send, and receive text.  You cannot run any programs on
	  them.  It is the computer to which you connect them that has all the
	  power to run text editors, compilers, email, games, and so
	  forth.</para>

	<para>There are hundreds of kinds of dumb terminals made by many
	  manufacturers, including Digital Equipment Corporation's VT-100 and
	  Wyse's WY-75.  Just about any kind will work with FreeBSD. Some
	  high-end terminals can even display graphics, but only certain
	  software packages can take advantage of these advanced
	  features.</para>

	<para>Dumb terminals are popular in work environments where workers do
	  not need access to graphical applications such as those provided by
	  the X Window System.</para>
      </sect3>

      <sect3 id="term-pcs">
	<title>PCs Acting as Terminals</title>

	<para>If a <link linkend="term-dumb">dumb terminal</link> has just
	  enough ability to display, send, and receive text, then certainly
	  any spare personal computer can be a dumb terminal. All you need is
	  the proper cable and some <emphasis>terminal emulation</emphasis>
	  software to run on the computer.</para>

	<para>Such a configuration is popular in homes.  For example, if your
	  spouse is busy working on your FreeBSD system's console, you can do
	  some text-only work at the same time from a less powerful personal
	  computer hooked up as a terminal to the FreeBSD system.</para>
      </sect3>

      <sect3 id="term-x">
	<title>X Terminals</title>

	<para>X terminals are the most sophisticated kind of terminal
	  available.  Instead of connecting to a serial port, they usually
	  connect to a network like Ethernet.  Instead of being relegated to
	  text-only applications, they can display any X application.</para>

	<para>We introduce X terminals just for the sake of completeness.
	  However, this chapter does <emphasis>not</emphasis> cover setup,
	  configuration, or use of X terminals.</para>
      </sect3>
    </sect2>

    <sect2 id="term-config">
      <title>Configuration</title>

      <para>This section describes what you need to configure on your FreeBSD
	system to enable a login session on a terminal.  It assumes you have
	already configured your kernel to support the serial port to which the
	terminal is connected&mdash;and that you have connected it.</para>

      <para>Recall from <xref linkend="boot"/> that the
	<command>init</command> process is responsible for all process
	control and initialization at system startup.  One of the
	tasks performed by <command>init</command> is to read the
	<filename>/etc/ttys</filename> file and start a
	<command>getty</command> process on the available terminals.
	The <command>getty</command> process is responsible for
	reading a login name and starting the <command>login</command>
	program.</para>

      <para>Thus, to configure terminals for your FreeBSD system the
	following steps should be taken as <username>root</username>:</para>

      <procedure>
	<step>
	  <para>Add a line to <filename>/etc/ttys</filename> for the entry in
	    the <filename>/dev</filename> directory for the serial port if it
	    is not already there.</para>
	</step>

	<step>
	  <para>Specify that <command>/usr/libexec/getty</command> be run on
	    the port, and specify the appropriate
	    <replaceable>getty</replaceable> type from the
	    <filename>/etc/gettytab</filename> file.</para>
	</step>

	<step>
	  <para>Specify the default terminal type.</para>
	</step>

	<step>
	  <para>Set the port to <quote>on.</quote></para>
	</step>

	<step>
	  <para>Specify whether the port should be
	    <quote>secure.</quote></para>
	</step>

	<step>
	  <para>Force <command>init</command> to reread the
	    <filename>/etc/ttys</filename> file.</para>
	</step>
      </procedure>

      <para>As an optional step, you may wish to create a custom
	<replaceable>getty</replaceable> type for use in step 2 by making an
	entry in <filename>/etc/gettytab</filename>.  This chapter does
	not explain how to do so; you are encouraged to see the
	  &man.gettytab.5; and the &man.getty.8; manual pages for more
	information.</para>

      <sect3 id="term-etcttys">
	<title>Adding an Entry to <filename>/etc/ttys</filename></title>

	<para>The <filename>/etc/ttys</filename> file lists all of the ports
	  on your FreeBSD system where you want to allow logins.  For example,
	  the first virtual console <filename>ttyv0</filename> has an entry in
	  this file.  You can log in on the console using this entry.  This
	  file also contains entries for the other virtual consoles, serial ports,
	  and pseudo-ttys.  For a hardwired terminal, just list the serial
	  port's <filename>/dev</filename> entry without the
	  <filename>/dev</filename> part (for example,
	  <filename>/dev/ttyv0</filename> would be listed as
	  <devicename>ttyv0</devicename>).</para>

	<para>A default FreeBSD install includes an
	  <filename>/etc/ttys</filename> file with support for the first
	  four serial ports: <filename>ttyd0</filename> through
	  <filename>ttyd3</filename>.  If you are attaching a terminal
	  to one of those ports, you do not need to add another entry.</para>

	<example id="ex-etc-ttys">
	  <title>Adding Terminal Entries to
	    <filename>/etc/ttys</filename></title>

	  <para>Suppose we would like to connect two terminals to the
	    system: a Wyse-50 and an old 286 IBM PC running
	    <application>Procomm</application> terminal software
	    emulating a VT-100 terminal.  We connect the Wyse to the
	    second serial port and the 286 to the sixth serial port (a
	    port on a multiport serial card).  The corresponding
	    entries in the <filename>/etc/ttys</filename> file would
	    look like this:</para>

	  <programlisting>ttyd1<co
	      id="co-ttys-line1col1"/>  "/usr/libexec/getty std.38400"<co
	      id="co-ttys-line1col2"/>  wy50<co
	      id="co-ttys-line1col3"/>  on<co
	      id="co-ttys-line1col4"/>  insecure<co
	      id="co-ttys-line1col5"/>
ttyd5   "/usr/libexec/getty std.19200"  vt100  on  insecure
	  </programlisting>

	  <calloutlist>
	    <callout arearefs="co-ttys-line1col1">
	      <para>The first field normally specifies the name of
	      the terminal special file as it is found in
	      <filename>/dev</filename>.</para>
	    </callout>
	    <callout arearefs="co-ttys-line1col2">

	      <para>The second field is the command to execute for
	        this line, which is usually &man.getty.8;.
	        <command>getty</command> initializes and opens the
	        line, sets the speed, prompts for a user name and then
	        executes the &man.login.1; program.</para>

	      <para>The <command>getty</command> program accepts one
		(optional) parameter on its command line, the
		<replaceable>getty</replaceable> type.  A
		<replaceable>getty</replaceable> type configures
		characteristics on the terminal line, like bps rate
		and parity. The <command>getty</command> program reads
		these characteristics from the file
		<filename>/etc/gettytab</filename>.</para>

	      <para>The file <filename>/etc/gettytab</filename>
		contains lots of entries for terminal lines both old
		and new.  In almost all cases, the entries that start
		with the text <literal>std</literal> will work for
		hardwired terminals. These entries ignore parity.
		There is a <literal>std</literal> entry for each bps
		rate from 110 to 115200.  Of course, you can add your
		own entries to this file. The &man.gettytab.5; manual
		page provides more information.</para>

	      <para>When setting the <replaceable>getty</replaceable>
		type in the <filename>/etc/ttys</filename> file, make
		sure that the communications settings on the terminal
		match.</para>

	      <para>For our example, the Wyse-50 uses no parity and
		connects at 38400&nbsp;bps.  The 286&nbsp;PC uses no parity and
		connects at 19200&nbsp;bps.</para>

	    </callout>

	    <callout arearefs="co-ttys-line1col3">

	      <para>The third field is the type of terminal usually
		connected to that tty line.  For dial-up ports,
		<literal>unknown</literal> or
		<literal>dialup</literal> is typically used in this
		field since users may dial up with practically any
		type of terminal or software.  For hardwired
		terminals, the terminal type does not change, so you
		can put a real terminal type from the &man.termcap.5;
		database file in this field.</para>

	      <para>For our example, the Wyse-50 uses the real
		terminal type while the 286 PC running
		<application>Procomm</application> will be set to
		emulate at VT-100. </para>

	    </callout>

	    <callout arearefs="co-ttys-line1col4">
	      <para>The fourth field specifies if the port should be
	        enabled.  Putting <literal>on</literal> here will have
	        the <command>init</command> process start the program
	        in the second field, <command>getty</command>.  If you
	        put <literal>off</literal> in this field, there will
	        be no <command>getty</command>, and hence no logins on
	        the port.</para>
	    </callout>

	    <callout arearefs="co-ttys-line1col5">
	      <para>The final field is used to specify whether the
	        port is secure.  Marking a port as secure means that
	        you trust it enough to allow the
	        <username>root</username> account (or any account with
	        a user ID of 0) to login from that port.  Insecure
	        ports do not allow <username>root</username> logins.
	        On an insecure port, users must login from
	        unprivileged accounts and then use &man.su.1; or a
	        similar mechanism to gain superuser privileges.</para>

	      <para>It is highly recommended that you use
		<quote>insecure</quote>
	        even for terminals that are behind locked doors.  It
	        is quite easy to login and use <command>su</command>
	        if you need superuser privileges.</para>
	    </callout>
	  </calloutlist>
	</example>
      </sect3>

      <sect3 id="term-hup">
	<title>Force <command>init</command> to Reread
	  <filename>/etc/ttys</filename></title>

	<para>After making the necessary changes to the
	  <filename>/etc/ttys</filename> file you should send a SIGHUP
	  (hangup) signal to the <command>init</command> process to
	  force it to re-read its configuration file.  For example:</para>

	<screen>&prompt.root; <userinput>kill -HUP 1</userinput></screen>

	<note>
	  <para><command>init</command> is always the first process run
	    on a system, therefore it will always have PID 1.</para>
	</note>

	<para>If everything is set up correctly, all cables are in
	  place, and the terminals are powered up, then a
	  <command>getty</command> process should be running on each
	  terminal and you should see login prompts on your terminals
	  at this point.</para>
      </sect3>
    </sect2>

    <sect2 id="term-debug">
      <title>Troubleshooting Your Connection</title>

      <para>Even with the most meticulous attention to detail, something could
	still go wrong while setting up a terminal.  Here is a list of
	symptoms and some suggested fixes.</para>

      <sect3>
	<title>No Login Prompt Appears</title>

	<para>Make sure the terminal is plugged in and powered up. If it
	  is a personal computer acting as a terminal, make sure it is
	  running terminal emulation software on the correct serial
	  port.</para>

	<para>Make sure the cable is connected firmly to both the terminal
	  and the FreeBSD computer.  Make sure it is the right kind of
	  cable.</para>

	<para>Make sure the terminal and FreeBSD agree on the bps rate and
	  parity settings.  If you have a video display terminal, make
	  sure the contrast and brightness controls are turned up.  If it
	  is a printing terminal, make sure paper and ink are in good
	  supply.</para>

	<para>Make sure that a <command>getty</command> process is running
	  and serving the terminal.  For example, to get a list of
	  running <command>getty</command> processes with
	  <command>ps</command>, type:</para>

        <screen>&prompt.root; <userinput>ps -axww|grep getty</userinput></screen>

	<para>You should see an entry for the terminal.  For
	  example, the following display shows that a
	  <command>getty</command> is running on the second serial
	  port <literal>ttyd1</literal> and is using the
	  <literal>std.38400</literal> entry in
	  <filename>/etc/gettytab</filename>:</para>

	<screen>22189  d1  Is+    0:00.03 /usr/libexec/getty std.38400 ttyd1</screen>

	<para>If no <command>getty</command> process is running, make sure
	  you have enabled the port in <filename>/etc/ttys</filename>.
	  Also remember to run <command>kill -HUP 1</command>
	  after modifying the <filename>ttys</filename> file.</para>

	<para>If the <command>getty</command> process is running
	  but the terminal still does not display a login prompt,
	  or if it displays a prompt but will not allow you to
	  type, your terminal or cable may not support hardware
	  handshaking. Try changing the entry in
	  <filename>/etc/ttys</filename> from
	  <literal>std.38400</literal> to
	  <literal>3wire.38400</literal> remember to run
	  <command>kill -HUP 1</command> after modifying
	  <filename>/etc/ttys</filename>). The
	  <literal>3wire</literal> entry is similar to
	  <literal>std</literal>, but ignores hardware
	  handshaking. You may need to reduce the baud rate or
	  enable software flow control when using
	  <literal>3wire</literal> to prevent buffer
	  overflows.</para>

      </sect3>

      <sect3>
	<title>If Garbage Appears Instead of a Login Prompt</title>

	<para>Make sure the terminal and FreeBSD agree on the bps rate and
	  parity settings.  Check the <command>getty</command> processes
	  to make sure the
	  correct <replaceable>getty</replaceable> type is in use.  If
	  not, edit <filename>/etc/ttys</filename> and run <command>kill
	  -HUP 1</command>.</para>

      </sect3>

      <sect3>
	<title>Characters Appear Doubled; the Password Appears When Typed</title>

	<para>Switch the terminal (or the terminal emulation software)
	  from <quote>half duplex</quote> or <quote>local echo</quote> to
	  <quote>full duplex.</quote></para>

      </sect3>
    </sect2>
  </sect1>

  <sect1 id="dialup">
    <sect1info>
      <authorgroup>
	<author>
	  <firstname>Guy</firstname>
	  <surname>Helmer</surname>
	  <contrib>Contributed by </contrib>
	</author>
      </authorgroup>
      <authorgroup>
        <author>
	  <firstname>Sean</firstname>
	  <surname>Kelly</surname>
	  <contrib>Additions by </contrib>
	</author>
      </authorgroup>
    </sect1info>
    <title>Dial-in Service</title>
    <indexterm><primary>dial-in service</primary></indexterm>

    <para>Configuring your FreeBSD system for dial-in service is very
      similar to connecting terminals except that you are dealing with
      modems instead of terminals.</para>

      <sect2>
	<title>External vs. Internal Modems</title>

	<para>External modems seem to be more convenient for dial-up, because
	  external modems often can be semi-permanently configured via
	  parameters stored in non-volatile RAM and they usually provide
	  lighted indicators that display the state of important RS-232
	  signals.  Blinking lights impress visitors, but lights are also very
	  useful to see whether a modem is operating properly.</para>

	<para>Internal modems usually lack non-volatile RAM, so their
	  configuration may be limited only to setting DIP switches.  If your
	  internal modem has any signal indicator lights, it is probably
	  difficult to view the lights when the system's cover is in
	  place.</para>

      <sect3>
	<title>Modems and Cables</title>
	<indexterm><primary>modem</primary></indexterm>

	<para>If you are using an external modem, then you will of
	  course need the proper cable.  A standard RS-232C serial
	  cable should suffice as long as all of the normal signals
	  are wired:</para>

          <table frame="none" pgwide="1" id="serialcomms-signal-names">
            <title>Signal Names</title>

            <tgroup cols="5">
              <thead>
                <row>
                  <entry align="left">Acronyms</entry>
                  <entry align="left">Names</entry>
                </row>
              </thead>

              <tbody>
                <row>
                  <entry><acronym>RD</acronym></entry>
                  <entry>Received Data</entry>
                </row>

                <row>
                  <entry><acronym>TD</acronym></entry>
                  <entry>Transmitted Data</entry>
                </row>

                <row>
                  <entry><acronym>DTR</acronym></entry>
                  <entry>Data Terminal Ready</entry>
                </row>

                <row>
                  <entry><acronym>DSR</acronym></entry>
                  <entry>Data Set Ready</entry>
                </row>

                <row>
                  <entry><acronym>DCD</acronym></entry>
                  <entry>Data Carrier Detect (RS-232's Received Line
                    Signal Detector)</entry>
                </row>

                <row>
                  <entry><acronym>SG</acronym></entry>
                  <entry>Signal Ground</entry>
                </row>

                <row>
                  <entry><acronym>RTS</acronym></entry>
                  <entry>Request to Send</entry>
                </row>

                <row>
                  <entry><acronym>CTS</acronym></entry>
                  <entry>Clear to Send</entry>
                </row>
              </tbody>
            </tgroup>
          </table>

	<para>FreeBSD needs the <acronym>RTS</acronym> and
	  <acronym>CTS</acronym> signals for flow control at speeds above
	  2400&nbsp;bps, the <acronym>CD</acronym> signal to detect when a call has
	  been answered or the line has been hung up, and the
	  <acronym>DTR</acronym> signal to reset the modem after a session is
	  complete.  Some cables are wired without all of the needed signals,
	  so if you have problems, such as a login session not going away when
	  the line hangs up, you may have a problem with your cable.</para>

	<para>Like other &unix; like operating systems, FreeBSD uses the
	  hardware signals to find out when a call has been answered
	  or a line has been hung up and to hangup and reset the modem
	  after a call.  FreeBSD avoids sending commands to the modem
	  or watching for status reports from the modem.  If you are
	  familiar with connecting modems to PC-based bulletin board
	  systems, this may seem awkward.</para>
      </sect3>
      </sect2>

      <sect2>
	<title>Serial Interface Considerations</title>

	<para>FreeBSD supports NS8250-, NS16450-, NS16550-, and NS16550A-based
	  EIA RS-232C (CCITT V.24) communications interfaces.  The 8250 and
	  16450 devices have single-character buffers.  The 16550 device
	  provides a 16-character buffer, which allows for better system
	  performance.  (Bugs in plain 16550's prevent the use of the
	  16-character buffer, so use 16550A's if possible).  Because
	  single-character-buffer devices require more work by the operating
	  system than the 16-character-buffer devices, 16550A-based serial
	  interface cards are much preferred. If the system has many active
	  serial ports or will have a heavy load, 16550A-based cards are
	  better for low-error-rate communications.</para>
      </sect2>

    <sect2>
      <title>Quick Overview</title>

      <indexterm><primary>getty</primary></indexterm>
      <para>As with terminals, <command>init</command> spawns a
	<command>getty</command> process for each configured serial
	port for dial-in connections.  For example, if a modem is
	attached to <filename>/dev/ttyd0</filename>, the command
	<command>ps ax</command> might show this:</para>

      <screen> 4850 ??  I      0:00.09 /usr/libexec/getty V19200 ttyd0</screen>

      <para>When a user dials the modem's line and the modems connect, the
	<acronym>CD</acronym> (Carrier Detect) line is reported by the modem.
	The kernel
	notices that carrier has been detected and completes
	<command>getty</command>'s open of the port.  <command>getty</command>
	sends a <prompt>login:</prompt> prompt at the specified initial line
	speed.  <command>getty</command> watches to see if legitimate
	characters are received, and, in a typical configuration, if it finds
	junk (probably due to the modem's connection speed being different
	than <command>getty</command>'s speed), <command>getty</command> tries
	adjusting the line speeds until it receives reasonable
	characters.</para>

      <indexterm>
        <primary><command>/usr/bin/login</command></primary>
      </indexterm>
      <para>After the user enters his/her login name,
	<command>getty</command> executes
	<filename>/usr/bin/login</filename>, which completes the login
	by asking for the user's password and then starting the user's
	shell.</para>
    </sect2>


    <sect2>
      <title>Configuration Files</title>

      <para>There are three system configuration files in the
	<filename>/etc</filename> directory that you will probably need to
	edit to allow dial-up access to your FreeBSD system.  The first,
	<filename>/etc/gettytab</filename>, contains configuration information
	for the <filename>/usr/libexec/getty</filename> daemon.  Second,
	<filename>/etc/ttys</filename> holds information that tells
	<filename>/sbin/init</filename> what <filename>tty</filename> devices
	should have <command>getty</command> processes running on them.
	Lastly, you can place port initialization commands in the
	<filename>/etc/rc.d/serial</filename> script.</para>

      <para>There are two schools of thought regarding dial-up modems on &unix;.
	One group likes to configure their modems and systems so that no matter
	at what speed a remote user dials in, the local computer-to-modem
	RS-232 interface runs at a locked speed.  The benefit of this
	configuration is that the remote user always sees a system login
	prompt immediately.  The downside is that the system does not know
	what a user's true data rate is, so full-screen programs like Emacs
	will not adjust their screen-painting methods to make their response
	better for slower connections.</para>

      <para>The other school configures their modems' RS-232 interface to vary
	its speed based on the remote user's connection speed.  For example,
	V.32bis (14.4&nbsp;Kbps) connections to the modem might make the modem run
	its RS-232 interface at 19.2&nbsp;Kbps, while 2400&nbsp;bps connections make the
	modem's RS-232 interface run at 2400&nbsp;bps. Because
	<command>getty</command> does not understand any particular modem's
	connection speed reporting, <command>getty</command> gives a
	<prompt>login:</prompt> message at an initial speed and watches the
	characters that come back in response.  If the user sees junk, it is
	assumed that they know they should press the
	<keycode>Enter</keycode> key until they see a recognizable
	prompt.  If the data rates do not match, <command>getty</command> sees
	anything the user types as <quote>junk</quote>, tries going to the next
	speed and gives the <prompt>login:</prompt> prompt again.  This
	procedure can continue ad nauseam, but normally only takes a keystroke
	or two before the user sees a good prompt.  Obviously, this login
	sequence does not look as clean as the former
	<quote>locked-speed</quote> method, but a user on a low-speed
	connection should receive better interactive response from full-screen
	programs.</para>

      <para>This section will try to give balanced configuration information,
	but is biased towards having the modem's data rate follow the
	connection rate.</para>

      <sect3>
	<title><filename>/etc/gettytab</filename></title>

  <indexterm>
    <primary><filename>/etc/gettytab</filename></primary>
  </indexterm>
	<para><filename>/etc/gettytab</filename> is a &man.termcap.5;-style
	  file of configuration information for &man.getty.8;.  Please see the
	    &man.gettytab.5; manual page for complete information on the
	  format of the file and the list of capabilities.</para>

	<sect4>
	  <title>Locked-speed Config</title>

	  <para>If you are locking your modem's data communications rate at a
	    particular speed, you probably will not need to make any changes
	    to <filename>/etc/gettytab</filename>.</para>
	</sect4>

	<sect4>
	  <title>Matching-speed Config</title>

	  <para>You will need to set up an entry in
	    <filename>/etc/gettytab</filename> to give
	    <command>getty</command> information about the speeds you wish to
	    use for your modem.  If you have a 2400&nbsp;bps modem, you can
	    probably use the existing <literal>D2400</literal> entry.</para>

	  <programlisting>#
# Fast dialup terminals, 2400/1200/300 rotary (can start either way)
#
D2400|d2400|Fast-Dial-2400:\
        :nx=D1200:tc=2400-baud:
3|D1200|Fast-Dial-1200:\
        :nx=D300:tc=1200-baud:
5|D300|Fast-Dial-300:\
        :nx=D2400:tc=300-baud:</programlisting>

	  <para>If you have a higher speed modem, you will probably need to
	    add an entry in <filename>/etc/gettytab</filename>; here is an
	    entry you could use for a 14.4&nbsp;Kbps modem with a top interface
	    speed of 19.2&nbsp;Kbps:</para>

	  <programlisting>#
# Additions for a V.32bis Modem
#
um|V300|High Speed Modem at 300,8-bit:\
        :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:</programlisting>

	  <para>This will result in 8-bit, no parity connections.</para>

	  <para>The example above starts the communications rate at 19.2&nbsp;Kbps
	    (for a V.32bis connection), then cycles through 9600&nbsp;bps (for
	    V.32), 2400&nbsp;bps, 1200&nbsp;bps, 300&nbsp;bps, and back to 19.2&nbsp;Kbps.
	    Communications rate cycling is implemented with the
	    <literal>nx=</literal> (<quote>next table</quote>) capability.
	    Each of the lines uses a <literal>tc=</literal> (<quote>table
	    continuation</quote>) entry to pick up the rest of the
	    <quote>standard</quote> settings for a particular data rate.</para>

	  <para>If you have a 28.8&nbsp;Kbps modem and/or you want to take
	    advantage of compression on a 14.4&nbsp;Kbps modem, you need to use a
	    higher communications rate than 19.2&nbsp;Kbps.  Here is an example of
	    a <filename>gettytab</filename> entry starting a 57.6&nbsp;Kbps:</para>

	  <programlisting>#
# Additions for a V.32bis or V.34 Modem
# Starting at 57.6 Kbps
#
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:</programlisting>

	  <para>If you have a slow CPU or a heavily loaded system and do
	    not have 16550A-based serial ports, you may receive
	    <errorname>sio</errorname>
	    <quote>silo</quote> errors at 57.6&nbsp;Kbps.</para>
	</sect4>
      </sect3>

      <sect3 id="dialup-ttys">
	<title><filename>/etc/ttys</filename></title>
	<indexterm>
	  <primary><filename>/etc/ttys</filename></primary>
	</indexterm>

	<para>Configuration of the <filename>/etc/ttys</filename> file
	  was covered in <xref linkend="ex-etc-ttys"/>.
	  Configuration for modems is similar but we must pass a
	  different argument to <command>getty</command> and specify a
	  different terminal type.  The general format for both
	  locked-speed and matching-speed configurations is:</para>

	<programlisting>ttyd0   "/usr/libexec/getty <replaceable>xxx</replaceable>"   dialup on</programlisting>

	<para>The first item in the above line is the device special file for
	  this entry &mdash; <literal>ttyd0</literal> means
	  <filename>/dev/ttyd0</filename> is the file that this
	  <command>getty</command> will be watching.  The second item,
	  <literal>"/usr/libexec/getty
	    <replaceable>xxx</replaceable>"</literal>
	  (<replaceable>xxx</replaceable> will be replaced by the initial
	  <filename>gettytab</filename> capability) is the process
	  <command>init</command> will run on the device.  The third item,
	  <literal>dialup</literal>, is the default terminal type.  The fourth
	  parameter, <literal>on</literal>, indicates to
	  <command>init</command> that the line is operational.  There can be
	  a fifth parameter, <literal>secure</literal>, but it should only be
	  used for terminals which are physically secure (such as the system
	  console).</para>

	<para>The default terminal type (<literal>dialup</literal> in the
	  example above) may depend on local preferences.
	  <literal>dialup</literal> is the traditional default terminal type
	  on dial-up lines so that users may customize their login scripts to
	  notice when the terminal is <literal>dialup</literal> and
	  automatically adjust their terminal type.  However, the author finds
	  it easier at his site to specify <literal>vt102</literal> as the
	  default terminal type, since the users just use VT102 emulation on
	  their remote systems.</para>

	<para>After you have made changes to <filename>/etc/ttys</filename>,
	  you may send the <command>init</command> process a
	  <acronym>HUP</acronym> signal to re-read the file.  You can use the
	  command

	<screen>&prompt.root; <userinput>kill -HUP 1</userinput></screen>

	  to send the signal.  If this is your first time setting up the
	  system, you may want to wait until your modem(s) are properly
          configured and connected before signaling <command>init</command>.
	  </para>

	<sect4>
	  <title>Locked-speed Config</title>

	  <para>For a locked-speed configuration, your
	    <filename>ttys</filename> entry needs to have a fixed-speed entry
	    provided to <command>getty</command>.  For a modem whose port
	    speed is locked at 19.2&nbsp;Kbps, the <filename>ttys</filename> entry
	    might look like this:</para>

	  <programlisting>ttyd0   "/usr/libexec/getty std.19200"   dialup on</programlisting>

	  <para>If your modem is locked at a different data rate,
	    substitute the appropriate value for
	    <literal>std.<replaceable>speed</replaceable></literal>
	    instead of <literal>std.19200</literal>.  Make sure that
	    you use a valid type listed in
	    <filename>/etc/gettytab</filename>.</para>
	</sect4>

	<sect4>
	  <title>Matching-speed Config</title>

	  <para>In a matching-speed configuration, your
	    <filename>ttys</filename> entry needs to reference the appropriate
	    beginning <quote>auto-baud</quote> (sic) entry in
	    <filename>/etc/gettytab</filename>.  For example, if you added the
	    above suggested entry for a matching-speed modem that starts at
	    19.2&nbsp;Kbps (the <filename>gettytab</filename> entry containing the
	    <literal>V19200</literal> starting point), your
	    <filename>ttys</filename> entry might look like this:</para>

	  <programlisting>ttyd0   "/usr/libexec/getty V19200"   dialup on</programlisting>
	</sect4>
      </sect3>

      <sect3>
	<title><filename>/etc/rc.d/serial</filename></title>
	<indexterm>
	  <primary>rc files</primary>
	  <secondary><filename>rc.serial</filename></secondary>
	</indexterm>

	<para>High-speed modems, like V.32, V.32bis, and V.34 modems,
	  need to use hardware (<literal>RTS/CTS</literal>) flow
	  control. You can add <command>stty</command> commands to
	  <filename>/etc/rc.d/serial</filename> to set the hardware flow
	  control flag in the FreeBSD kernel for the modem
	  ports.</para>

	<para>For example to set the <literal>termios</literal> flag
	  <varname>crtscts</varname> on serial port #1's
	  (<devicename>COM2</devicename>) dial-in and dial-out initialization
	  devices, the following lines could be added to
	  <filename>/etc/rc.d/serial</filename>:</para>
	<programlisting># Serial port initial configuration
stty -f /dev/ttyd1.init crtscts
stty -f /dev/cuad1.init crtscts</programlisting>

      </sect3>
    </sect2>

    <sect2>
      <title>Modem Settings</title>

      <para>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 &ms-dos; or <command>tip</command> under FreeBSD) to set the
	parameters.  Connect to the modem using the same communications speed
	as the initial speed <command>getty</command> will use and configure
	the modem's non-volatile RAM to match these requirements:</para>

      <itemizedlist>
	<listitem>
	  <para><acronym>CD</acronym> asserted when connected</para>
	</listitem>

	<listitem>
	  <para><acronym>DTR</acronym> asserted for operation; dropping DTR
	    hangs up line and resets modem</para>
	</listitem>

	<listitem>
	  <para><acronym>CTS</acronym> transmitted data flow control</para>
	</listitem>

	<listitem>
	  <para>Disable <acronym>XON/XOFF</acronym> flow control</para>
	</listitem>

	<listitem>
	  <para><acronym>RTS</acronym> received data flow control</para>
	</listitem>

	<listitem>
	  <para>Quiet mode (no result codes)</para>
	</listitem>

	<listitem>
	  <para>No command echo</para>
	</listitem>
      </itemizedlist>

      <para>Please read the documentation for your modem to find out what
	commands and/or DIP switch settings you need to give it.</para>

      <para>For example, to set the above parameters on a &usrobotics;
	&sportster; 14,400 external modem, one could give these commands to
	the modem:</para>

      <programlisting>ATZ
AT&amp;C1&amp;D2&amp;H1&amp;I0&amp;R2&amp;W</programlisting>

      <para>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.</para>

      <para>The &usrobotics; &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:</para>

      <itemizedlist>
	<listitem>
	  <para>Switch 1: UP &mdash; DTR Normal</para>
	</listitem>

	<listitem>
	  <para>Switch 2: N/A (Verbal Result Codes/Numeric Result
	    Codes)</para>
	</listitem>

	<listitem>
	  <para>Switch 3: UP &mdash; Suppress Result Codes</para>
	</listitem>

	<listitem>
	  <para>Switch 4: DOWN &mdash; No echo, offline commands</para>
	</listitem>

	<listitem>
	  <para>Switch 5: UP &mdash; Auto Answer</para>
	</listitem>

	<listitem>
	  <para>Switch 6: UP &mdash; Carrier Detect Normal</para>
	</listitem>

	<listitem>
	  <para>Switch 7: UP &mdash; Load NVRAM Defaults</para>
	</listitem>

	<listitem>
	  <para>Switch 8: N/A (Smart Mode/Dumb Mode)</para>
	</listitem>
      </itemizedlist>

      <para>Result codes should be disabled/suppressed for dial-up modems to
	avoid problems that can occur if <command>getty</command> mistakenly
	gives a <prompt>login:</prompt> prompt to a modem that is in command
	mode and the modem echoes the command or returns a result
	code.  This sequence can result in a extended, silly conversation
 	between <command>getty</command> and the modem.</para>

      <sect3>
	<title>Locked-speed Config</title>

	<para>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 &usrobotics; &sportster; 14,400 external
	  modem, these commands will lock the modem-to-computer data rate at
	  the speed used to issue the commands:</para>

	<programlisting>ATZ
AT&amp;B1&amp;W</programlisting>
      </sect3>

      <sect3>
	<title>Matching-speed Config</title>

	<para>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 &usrobotics; &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:</para>

	<programlisting>ATZ
AT&amp;B2&amp;W</programlisting>
      </sect3>

      <sect3>
	<title>Checking the Modem's Configuration</title>

	<para>Most high-speed modems provide commands to view the modem's
	  current operating parameters in a somewhat human-readable fashion.
	  On the &usrobotics; &sportster; 14,400 external modems, the command
	  <command>ATI5</command> displays the settings that are stored in the
	  non-volatile RAM.  To see the true operating parameters of the modem
	  (as influenced by the modem's DIP switch settings), use the commands
	  <command>ATZ</command> and then <command>ATI4</command>.</para>

	<para>If you have a different brand of modem, check your modem's
	  manual to see how to double-check your modem's configuration
	  parameters.</para>
      </sect3>
    </sect2>

    <sect2>
      <title>Troubleshooting</title>

      <para>Here are a few steps you can follow to check out the dial-up modem
	on your system.</para>

      <sect3>
	<title>Checking Out the FreeBSD System</title>

	<para>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 <acronym>DTR</acronym> indicator lights when the
	  <prompt>login:</prompt> prompt appears on the system's console
	  &mdash; if it lights up, that should mean that FreeBSD has started a
	  <command>getty</command> process on the appropriate communications
	  port and is waiting for the modem to accept a call.</para>

	<para>If the <acronym>DTR</acronym> indicator does not light, login to
	  the FreeBSD system through the console and issue a <command>ps
	    ax</command> to see if FreeBSD is trying to run a
	  <command>getty</command> process on the correct port. You should see
	  lines like these among the processes displayed:</para>

	<screen>  114 ??  I      0:00.10 /usr/libexec/getty V19200 ttyd0
  115 ??  I      0:00.10 /usr/libexec/getty V19200 ttyd1</screen>

	<para>If you see something different, like this:</para>

	  <screen>  114 d0  I      0:00.10 /usr/libexec/getty V19200 ttyd0</screen>

	<para>and the modem has not accepted a call yet, this means that
	  <command>getty</command> has completed its open on the
	  communications port.  This could indicate a problem with the cabling
	  or a mis-configured modem, because <command>getty</command> should
	  not be able to open the communications port until
	  <acronym>CD</acronym> (carrier detect) has been asserted by the
	  modem.</para>

	<para>If you do not see any <command>getty</command> processes waiting
	  to open the desired
	  <filename>ttyd<replaceable>N</replaceable></filename> port,
	  double-check your entries in <filename>/etc/ttys</filename> to see
	  if there are any mistakes there.  Also, check the log file
	  <filename>/var/log/messages</filename> to see if there are any log
	  messages from <command>init</command> or <command>getty</command>
	  regarding any problems.  If there are any messages, triple-check the
	  configuration files <filename>/etc/ttys</filename> and
	  <filename>/etc/gettytab</filename>, as well as the appropriate
	  device special files <filename>/dev/ttydN</filename>, for any
	  mistakes, missing entries, or missing device special files.</para>
      </sect3>

      <sect3>
	<title>Try Dialing In</title>

	<para>Try dialing into the system; be sure to use 8 bits, no parity,
	  and 1
	  stop bit on the remote system.  If you do not get a prompt right
	  away, or get garbage, try pressing <keycode>Enter</keycode>
	  about once per second.  If you still do not see a
	  <prompt>login:</prompt> prompt after a while, try sending a
	  <command>BREAK</command>. If you are using a high-speed modem to do
	  the dialing, try dialing again after locking the dialing modem's
	  interface speed (via <command>AT&amp;B1</command> on a &usrobotics;
	  &sportster; modem, for example).</para>

	<para>If you still cannot get a <prompt>login:</prompt> prompt, check
	  <filename>/etc/gettytab</filename> again and double-check
	  that</para>

	<itemizedlist>
	  <listitem>
	    <para>The initial capability name specified in
	      <filename>/etc/ttys</filename> for the line matches a name of a
	      capability in <filename>/etc/gettytab</filename></para>
		</listitem>

	  <listitem>
	    <para>Each <literal>nx=</literal> entry matches another
	      <filename>gettytab</filename> capability name</para>
	  </listitem>

	  <listitem>
	    <para>Each <literal>tc=</literal> entry matches another
	      <filename>gettytab</filename> capability name</para>
	  </listitem>
	</itemizedlist>

	<para>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
	  <acronym>DTR</acronym> is asserted.  If the modem seems to be
	  configured correctly, verify that the <acronym>DTR</acronym> line is
	  asserted by checking the modem's indicator lights (if it has
	  any).</para>

	<para>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 your problem, and the good
	  folks on the list will try to help.</para>
      </sect3>
    </sect2>

  </sect1>

  <sect1 id="dialout">
    <title>Dial-out Service</title>
    <indexterm><primary>dial-out service</primary></indexterm>

    <para>The following are tips for getting your host to be able to connect
      over the modem to another computer.  This is appropriate for
      establishing a terminal session with a remote host.</para>

    <para>This is useful to log onto a BBS.</para>

    <para>This kind of connection can be extremely helpful to get a file on
      the Internet if you have problems with PPP.  If you need to FTP
      something and PPP is broken, use the terminal session to FTP it. Then
      use zmodem to transfer it to your machine.</para>

    <sect2>
      <title>My Stock Hayes Modem Is Not Supported, What Can I Do?</title>

      <para>Actually, the manual page for <command>tip</command> is out of date.
	There is a generic Hayes dialer already built in. Just use
	<literal>at=hayes</literal> in your <filename>/etc/remote</filename>
	file.</para>

      <para>The Hayes driver is not smart enough to recognize some of the
	advanced features of newer modems&mdash;messages like
	<literal>BUSY</literal>, <literal>NO DIALTONE</literal>, or
	<literal>CONNECT 115200</literal> will just confuse it.  You should
	turn those messages off when you use <command>tip</command> (using
	<command>ATX0&amp;W</command>).</para>

      <para>Also, the dial timeout for <command>tip</command> is 60 seconds.
	Your modem should use something less, or else tip will think there is
	a communication problem.  Try <command>ATS7=45&amp;W</command>.</para>

      <note>
	<para>As shipped, <command>tip</command> does not yet support
	  Hayes modems fully.  The solution is to edit the file
	  <filename>tipconf.h</filename> in the directory
	  <filename>/usr/src/usr.bin/tip/tip</filename>. Obviously you need the
	  source distribution to do this.</para>

	<para>Edit the line <literal>#define HAYES 0</literal> to
	  <literal>#define HAYES 1</literal>.  Then <command>make</command> and
	  <command>make install</command>.  Everything works nicely after
	  that.</para>
      </note>
    </sect2>

    <sect2 id="direct-at">
      <title>How Am I Expected to Enter These AT Commands?</title>

      <indexterm>
        <primary><filename>/etc/remote</filename></primary>
      </indexterm>
      <para>Make what is called a <quote>direct</quote> entry in your
	<filename>/etc/remote</filename> file.  For example, if your modem is
	hooked up to the first serial port, <filename>/dev/cuad0</filename>,
	then put in the following line:</para>

      <programlisting>cuad0:dv=/dev/cuad0:br#19200:pa=none</programlisting>

      <para>Use the highest bps rate your modem supports in the br capability.
	Then, type <command>tip cuad0</command> and you will be connected to
	your modem.</para>

      <para>Or use <command>cu</command> as <username>root</username> with the
	following command:</para>

      <screen>&prompt.root; <userinput>cu -l<replaceable>line</replaceable> -s<replaceable>speed</replaceable></userinput></screen>

      <para><replaceable>line</replaceable> is the serial port
	(e.g.<filename>/dev/cuad0</filename>) and
	<replaceable>speed</replaceable> is the speed
	(e.g.<literal>57600</literal>).  When you are done entering the AT
	commands hit <keycap>~.</keycap> to exit.</para>
    </sect2>

    <sect2>
      <title>The <literal>@</literal> Sign for the pn Capability Does Not
	Work!</title>

      <para>The <literal>@</literal> sign in the phone number capability tells
	tip to look in <filename>/etc/phones</filename> for a phone number.
	But the <literal>@</literal> sign is also a special character in
	capability files like <filename>/etc/remote</filename>.  Escape it
	with a backslash:</para>

      <programlisting>pn=\@</programlisting>
    </sect2>

    <sect2>
      <title>How Can I Dial a Phone Number on the Command Line?</title>

      <para>Put what is called a <quote>generic</quote> entry in your
	<filename>/etc/remote</filename> file.  For example:</para>

      <programlisting>tip115200|Dial any phone number at 115200 bps:\
        :dv=/dev/cuad0:br#115200:at=hayes:pa=none:du:
tip57600|Dial any phone number at 57600 bps:\
        :dv=/dev/cuad0:br#57600:at=hayes:pa=none:du:</programlisting>

      <para>Then you can do things like:</para>

      <screen>&prompt.root; <userinput>tip -115200 5551234</userinput></screen>

      <para>If you prefer <command>cu</command> over <command>tip</command>,
	use a generic <literal>cu</literal> entry:</para>

      <programlisting>cu115200|Use cu to dial any number at 115200bps:\
        :dv=/dev/cuad1:br#57600:at=hayes:pa=none:du:</programlisting>

      <para>and type:</para>

      <screen>&prompt.root; <userinput>cu 5551234 -s 115200</userinput></screen>
    </sect2>

    <sect2>
      <title>Do I Have to Type in the bps Rate Every Time I Do That?</title>

      <para>Put in an entry for <literal>tip1200</literal> or
	<literal>cu1200</literal>, but go ahead and use whatever bps rate is
	appropriate with the br capability.  <command>tip</command> thinks a
	good default is 1200&nbsp;bps which is why it looks for a
	<literal>tip1200</literal> entry.  You do not have to use 1200&nbsp;bps,
	though.</para>
    </sect2>

    <sect2>
      <title>I Access a Number of Hosts Through a Terminal Server</title>

      <para>Rather than waiting until you are connected and typing
	<command>CONNECT &lt;host&gt;</command> each time, use tip's
	<literal>cm</literal> capability.  For example, these entries in
	<filename>/etc/remote</filename>:</para>

      <programlisting>pain|pain.deep13.com|Forrester's machine:\
        :cm=CONNECT pain\n:tc=deep13:
muffin|muffin.deep13.com|Frank's machine:\
        :cm=CONNECT muffin\n:tc=deep13:
deep13:Gizmonics Institute terminal server:\
        :dv=/dev/cuad2:br#38400:at=hayes:du:pa=none:pn=5551234:</programlisting>

      <para>will let you type <command>tip pain</command> or <command>tip
	  muffin</command> to connect to the hosts pain or muffin, and
	<command>tip deep13</command> to get to the terminal server.</para>
    </sect2>

    <sect2>
      <title>Can Tip Try More Than One Line for Each Site?</title>

      <para>This is often a problem where a university has several modem lines
	and several thousand students trying to use them.</para>

      <para>Make an entry for your university in
	<filename>/etc/remote</filename> and use <literal>@</literal> for the
	<literal>pn</literal> capability:</para>

      <programlisting>big-university:\
        :pn=\@:tc=dialout
dialout:\
        :dv=/dev/cuad3:br#9600:at=courier:du:pa=none:</programlisting>

      <para>Then, list the phone numbers for the university in
	<filename>/etc/phones</filename>:</para>

      <programlisting>big-university 5551111
big-university 5551112
big-university 5551113
big-university 5551114</programlisting>

      <para><command>tip</command> will try each one in the listed order, then
	give up.  If you want to keep retrying, run <command>tip</command> in
	a while loop.</para>
    </sect2>

    <sect2>
      <title>Why Do I Have to Hit
        <keycombo action="simul">
          <keycap>Ctrl</keycap>
          <keycap>P</keycap>
        </keycombo>
        Twice to Send
        <keycombo action="simul">
          <keycap>Ctrl</keycap>
          <keycap>P</keycap>
        </keycombo>
        Once?</title>

      <para><keycombo action="simul"><keycap>Ctrl</keycap><keycap>P</keycap></keycombo> is the default <quote>force</quote> character, used to tell
	<command>tip</command> that the next character is literal data.  You
	can set the force character to any other character with the
	<command>~s</command> escape, which means <quote>set a
	variable.</quote></para>

      <para>Type
	<command>~sforce=<replaceable>single-char</replaceable></command>
	followed by a newline.  <replaceable>single-char</replaceable> is any
	single character. If you leave out
	<replaceable>single-char</replaceable>, then the force character is
	the nul character, which you can get by typing
	<keycombo action="simul">
	  <keycap>Ctrl</keycap><keycap>2</keycap>
	</keycombo>
	or
	<keycombo action="simul">
	  <keycap>Ctrl</keycap><keycap>Space</keycap>
	</keycombo>.
	A pretty good value for <replaceable>single-char</replaceable> is
	<keycombo action="simul">
	  <keycap>Shift</keycap>
	  <keycap>Ctrl</keycap>
	  <keycap>6</keycap>
	</keycombo>, which is only used on some terminal
	servers.</para>

      <para>You can have the force character be whatever you want by
	specifying the following in your <filename>&#36;HOME/.tiprc</filename>
	file:</para>

      <programlisting>force=&lt;single-char&gt;</programlisting>
    </sect2>

    <sect2>
      <title>Suddenly Everything I Type Is in Upper Case??</title>

      <para>You must have pressed
	<keycombo action="simul">
	  <keycap>Ctrl</keycap>
	  <keycap>A</keycap>
	</keycombo>, <command>tip</command>'s
	<quote>raise character,</quote> specially designed for people with
	broken caps-lock keys.  Use <command>~s</command> as above and set the
	variable <literal>raisechar</literal> to something reasonable.  In
	fact, you can set it to the same as the force character, if you never
	expect to use either of these features.</para>

      <para>Here is a sample .tiprc file perfect for
        <application>Emacs</application> users who need to type
	<keycombo action="simul">
	  <keycap>Ctrl</keycap><keycap>2</keycap>
	</keycombo>
	and
	<keycombo action="simul">
	  <keycap>Ctrl</keycap><keycap>A</keycap>
	</keycombo>
	a lot:</para>

      <programlisting>force=^^
raisechar=^^</programlisting>

      <para>The ^^ is
	<keycombo action="simul">
	  <keycap>Shift</keycap><keycap>Ctrl</keycap><keycap>6</keycap>
	</keycombo>.</para>

    </sect2>

    <sect2>
      <title>How Can I Do File Transfers with <command>tip</command>?</title>

      <para>If you are talking to another &unix; system, you can send and
	receive files with <command>~p</command> (put) and
	<command>~t</command> (take).  These commands run
	<command>cat</command> and <command>echo</command> on the remote
	system to accept and send files.  The syntax is:</para>

      <cmdsynopsis>
	<command>~p</command>
	<arg choice="plain">local-file</arg>
	<arg choice="opt">remote-file</arg>
      </cmdsynopsis>

      <cmdsynopsis>
	<command>~t</command>
	<arg choice="plain">remote-file</arg>
	<arg choice="opt">local-file</arg>
      </cmdsynopsis>

      <para>There is no error checking, so you probably should use another
	protocol, like zmodem.</para>
    </sect2>

    <sect2>
      <title>How Can I Run zmodem with <command>tip</command>?</title>

      <para>To receive files, start the sending program on the remote end.
	Then, type <command>~C rz</command> to begin receiving them
	locally.</para>

      <para>To send files, start the receiving program on the remote end.
	Then, type <command>~C sz <replaceable>files</replaceable></command>
	to send them to the remote system.</para>
    </sect2>
  </sect1>

  <sect1 id="serialconsole-setup">
    <sect1info>
      <authorgroup>
        <author>
	  <firstname>Kazutaka</firstname>
	  <surname>YOKOTA</surname>
	  <contrib>Contributed by </contrib>
	</author>
      </authorgroup>
      <authorgroup>
	<author>
	  <firstname>Bill</firstname>
	  <surname>Paul</surname>
	  <contrib>Based on a document by </contrib>
	</author>
      </authorgroup>
    </sect1info>
    <title>Setting Up the Serial Console</title>
    <indexterm><primary>serial console</primary></indexterm>

    <sect2 id="serialconsole-intro">
      <title>Introduction</title>

      <para>FreeBSD has the ability to boot on a system with only
	a dumb terminal on a serial port as a console.  Such a configuration
	should be useful for two classes of people:  system administrators who
	wish to install FreeBSD on machines that have no keyboard or monitor
	attached, and developers who want to debug the kernel or device
	drivers.</para>

      <para>As described in <xref linkend="boot"/>, FreeBSD employs a three stage
	bootstrap.  The first two stages are in the boot block code which is
	stored at the beginning of the FreeBSD slice on the boot disk.  The
	boot block will then load and run the boot loader
	(<filename>/boot/loader</filename>) as the third stage code.</para>

      <para>In order to set up the serial console you must configure the boot
	block code, the boot loader code and the kernel.</para>

    </sect2>

    <sect2 id="serialconsole-howto-fast">
      <title>Serial Console Configuration, Terse Version</title>

      <para>This section assumes that you are using the default setup
	and just want a fast overview of setting up the serial
	console.</para>

      <procedure>

	<step>
	  <para>Connect the serial cable to COM1 and the controlling
	    terminal.</para>
	</step>

	<step>
	  <para>To see all boot messages on the serial console, issue
	    the following command while logged in as the superuser:</para>
	  <screen>&prompt.root; echo 'console="comconsole"' &gt;&gt; /boot/loader.conf</screen>
	</step>

	<step>
	  <para>Edit <filename>/etc/ttys</filename> and change
	    <literal>off</literal> to <literal>on</literal> and
	    <literal>dialup</literal> to <literal>vt100</literal> for the
	    <literal>ttyd0</literal> entry.  Otherwise a password will not be
	    required to connect via the serial console, resulting in a
	    potential security hole.</para>
	</step>

	<step>
	  <para>Reboot the system to see if the changes took effect.</para>
	</step>

      </procedure>

      <para>If a different configuration is required, a more in depth
	configuration explanation exists in
	<xref linkend="serialconsole-howto"/>.</para>
    </sect2>

    <sect2 id="serialconsole-howto">
      <title>Serial Console Configuration</title>

      <procedure>
	<step>
	  <para>Prepare a serial cable.</para>

	  <indexterm><primary>null-modem cable</primary></indexterm>
	  <para>You will need either a null-modem cable or a standard serial
	    cable and a null-modem adapter.  See <xref linkend="serial-cables-ports"/> for
	    a discussion on serial cables.</para>
	</step>

	<step>
	  <para>Unplug your keyboard.</para>

	  <para>Most PC systems probe for the keyboard during the Power-On
	    Self-Test (POST) and will generate an error if the keyboard is not
	    detected.  Some machines complain loudly about the lack of a
	    keyboard and will not continue to boot until it is plugged
	    in.</para>

	  <para>If your computer complains about the error, but boots anyway,
	    then you do not have to do anything special.  (Some machines with
	    Phoenix BIOS installed merely say <errorname>Keyboard
	      failed</errorname> and continue to boot normally.)</para>

	  <para>If your computer refuses to boot without a keyboard attached
	    then you will have to configure the BIOS so that it ignores this
	    error (if it can).  Consult your motherboard's manual for details
	    on how to do this.</para>

	  <tip>
	    <para>Set the keyboard to <quote>Not installed</quote> in the
	      BIOS setup.  You will still
	      be able to use your keyboard.  All this does is tell the BIOS
	      not to probe for a keyboard at power-on.  Your BIOS should not
	      complain if the keyboard is absent.  You can leave the
	      keyboard plugged in even with this flag set to <quote>Not
	      installed</quote> and the keyboard will still work.</para>
	  </tip>

	  <note>
	    <para>If your system has a &ps2; mouse, chances are very good  that
	      you may have to unplug your mouse as well as your keyboard.
	      This is because &ps2; mice share some hardware with the keyboard
	      and leaving the mouse plugged in can fool the keyboard probe
	      into thinking the keyboard is still there.  It is said that a
	      Gateway 2000 Pentium 90&nbsp;MHz system with an AMI BIOS that behaves
	      this way.  In general, this is not a problem since the mouse is
	      not much good without the keyboard anyway.</para>
	  </note>
	</step>

	<step>
	  <para>Plug a dumb terminal into <devicename>COM1</devicename>
	    (<devicename>sio0</devicename>).</para>

	  <para>If you do not have a dumb terminal, you can use an old PC/XT
	    with a modem program, or the serial port on another &unix; box.  If
	    you do not have a <devicename>COM1</devicename>
	    (<devicename>sio0</devicename>), get one.  At this time, there is
	    no way to select a port other than <devicename>COM1</devicename>
	    for the boot blocks without recompiling the boot blocks.  If you
	    are already using <devicename>COM1</devicename> for another
	    device, you will have to temporarily remove that device and
	    install a new boot block and kernel once you get FreeBSD up and
	    running. (It is assumed that <devicename>COM1</devicename> will
	    be available on a file/compute/terminal server anyway; if you
	    really need <devicename>COM1</devicename> for something else
	    (and you cannot switch that something else to
	    <devicename>COM2</devicename> (<devicename>sio1</devicename>)),
	    then you probably should not even be bothering with all this in
	    the first place.)</para>
	</step>

	<step>
	  <para>Make sure the configuration file of your kernel has
	    appropriate flags set for <devicename>COM1</devicename>
	    (<devicename>sio0</devicename>).</para>

	  <para>Relevant flags are:</para>

	  <variablelist>
	    <varlistentry>
	      <term><literal>0x10</literal></term>

	      <listitem>
		<para>Enables console support for this unit.  The other
		  console flags are ignored unless this is set. Currently, at
		  most one unit can have console support;  the first one (in
		  config file order) with this flag set is preferred.  This
		  option alone will not make the serial port the console.  Set
		  the following flag or use the <option>-h</option> option
		  described below, together with this flag.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><literal>0x20</literal></term>

	      <listitem>
		<para>Forces this unit to be the console (unless there is
		  another higher priority console), regardless of the
		  <option>-h</option> option discussed below.
		  The flag <literal>0x20</literal> must be used
		  together with the <option>0x10</option> flag.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><literal>0x40</literal></term>

	      <listitem>
		<para>Reserves this unit (in conjunction with
		  <literal>0x10</literal>) and makes the unit
		  unavailable for normal access.  You should not set
		  this flag to the serial port unit which you want to
		  use as the serial console.  The only use of this
		  flag is to designate the unit for kernel remote
		  debugging.  See <ulink
		  url="&url.books.developers-handbook;/index.html">The
		  Developer's Handbook</ulink> for more information on
		  remote debugging.</para>

		<note>
		  <para>In FreeBSD&nbsp;4.0 or later the semantics of the
		    flag <literal>0x40</literal> are slightly different and
		    there is another flag to specify a serial port for remote
		    debugging.</para>
		</note>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>Example:</para>

	  <programlisting>device sio0 at isa? port IO_COM1 flags 0x10 irq 4</programlisting>

	  <para>See the &man.sio.4; manual page for more details.</para>

	  <para>If the flags were not set, you need to run UserConfig (on a
	    different console) or recompile the kernel.</para>
	</step>

	<step>
	  <para>Create <filename>boot.config</filename> in the root directory
	    of the <literal>a</literal> partition on the boot drive.</para>

	  <para>This file will instruct the boot block code how you would like
	    to boot the system.  In order to activate the serial console, you
	    need one or more of the following options&mdash;if you want
	    multiple options, include them all on the same line:</para>

	  <variablelist>
	    <varlistentry>
	      <term><option>-h</option></term>

	      <listitem>
		<para>Toggles internal and serial consoles.  You can use this
		  to switch console devices.  For instance, if you boot from
		  the internal (video) console, you can use
		  <option>-h</option> to direct the boot loader and the kernel
		  to use the serial port as its console device. Alternatively,
		  if you boot from the serial port, you can use the
		  <option>-h</option> to tell the boot loader and the kernel
		  to use the video display as the console instead.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><option>-D</option></term>

	      <listitem>
		<para>Toggles single and dual console configurations.  In the
		  single configuration the console will be either the internal
		  console (video display) or the serial port, depending on the
		  state of the <option>-h</option> option above.  In the dual
		  console configuration, both the video display  and the
		  serial port will become the console at the same time,
		  regardless of the state of the <option>-h</option> option.
		  However, note that the dual console configuration takes  effect
		  only during the boot block is running.  Once the boot loader
		  gets control, the console specified by the
		  <option>-h</option> option becomes the only console.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><option>-P</option></term>

	      <listitem>
		<para>Makes the boot block probe the keyboard.  If no keyboard
		  is found, the <option>-D</option> and <option>-h</option>
		  options are automatically set.</para>

		<note>
		  <para>Due to space constraints in the current version of the
		    boot blocks, the <option>-P</option> option is capable of
		    detecting extended keyboards only.  Keyboards with less
		    than 101 keys (and without F11 and F12  keys) may not be
		    detected.  Keyboards on some laptop computers may not be
		    properly found because of this limitation.  If this is
		    the case with your system, you have to abandon using
		    the <option>-P</option> option.  Unfortunately there is no
		    workaround for this problem.</para>
		</note>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>Use either the <option>-P</option> option to select the
	    console automatically, or the <option>-h</option> option to
	    activate the serial console.</para>

	  <para>You may include other options described in &man.boot.8; as
	    well.</para>

	  <para>The options, except for <option>-P</option>, will be passed to
	    the boot loader (<filename>/boot/loader</filename>).  The boot
	    loader will determine which of the internal video or the serial
	    port should become the console by examining the state of the
	    <option>-h</option> option alone.  This means that if you specify
	    the <option>-D</option> option but not the <option>-h</option>
	    option in <filename>/boot.config</filename>, you can use the
	    serial port as the console only during the boot block;  the boot
	    loader will use the internal video display as the console.</para>
	</step>

	<step>
	  <para>Boot the machine.</para>

	  <para>When you start your FreeBSD box, the boot blocks will echo the
	    contents of <filename>/boot.config</filename> to the console.  For
	    example:</para>

	  <screen>/boot.config: -P
Keyboard: no</screen>

	  <para>The second line appears only if you put <option>-P</option> in
	    <filename>/boot.config</filename> and indicates presence/absence
	    of the keyboard.  These messages go to either serial or internal
	    console, or both, depending on the option in
	    <filename>/boot.config</filename>.</para>

	  <informaltable frame="none" pgwide="1">
	    <tgroup cols="2">
	      <thead>
		<row>
		  <entry align="left">Options</entry>
		  <entry align="left">Message goes to</entry>
		</row>
	      </thead>

	      <tbody>
		<row>
		  <entry>none</entry>
		  <entry>internal console</entry>
		</row>

		<row>
		  <entry><option>-h</option></entry>
		  <entry>serial console</entry>
		</row>

		<row>
		  <entry><option>-D</option></entry>
		  <entry>serial and internal consoles</entry>
		</row>

		<row>
		  <entry><option>-Dh</option></entry>
		  <entry>serial and internal consoles</entry>
		</row>

		<row>
		  <entry><option>-P</option>, keyboard present</entry>
		  <entry>internal console</entry>
		</row>

		<row>
		  <entry><option>-P</option>, keyboard absent</entry>
		  <entry>serial console</entry>
		</row>
	      </tbody>
	    </tgroup>
	  </informaltable>

	  <para>After the above messages, there will be a small pause before
	    the boot blocks continue loading the boot loader and before any
	    further messages printed to the console.  Under normal
	    circumstances, you do not need to interrupt the boot blocks, but
	    you may want to do so in order to make sure things are set up
	    correctly.</para>

	  <para>Hit any key, other than <keycode>Enter</keycode>, at the console to
	    interrupt the boot process.  The boot blocks will then prompt you
	    for further action.  You should now see something like:</para>

	  <screen>>> FreeBSD/i386 BOOT
Default: 0:ad(0,a)/boot/loader
boot:</screen>

	  <para>Verify the above message appears on either the serial or
	    internal console or both, according to the options you put in
	    <filename>/boot.config</filename>.  If the message appears in the
	    correct console, hit <keycode>Enter</keycode> to continue the boot
	    process.</para>

	  <para>If you want the serial console but you do not see the prompt
	    on the serial terminal, something is wrong with your settings.  In
	    the meantime, you enter <option>-h</option> and hit Enter/Return
	    (if possible) to tell the boot block (and then the boot loader and
	    the kernel) to choose the serial port for the console. Once the
	    system is up, go back and check what went wrong.</para>
	</step>
      </procedure>

      <para>After the boot loader is loaded and you are in the third stage of
	the boot process you can still switch between the internal console and
	the serial console by setting appropriate environment variables in the
	boot loader.  See <xref linkend="serialconsole-loader"/>.</para>
    </sect2>

  <sect2 id="serialconsole-summary">
    <title>Summary</title>

      <para>Here is the summary of various settings discussed in this section
	and the console eventually selected.</para>

      <sect3>
	<title>Case 1: You Set the Flags to 0x10 for
	  <devicename>sio0</devicename></title>

	<programlisting>device sio0 at isa? port IO_COM1 flags 0x10 irq 4</programlisting>

	<informaltable frame="none" pgwide="1">
	  <tgroup cols="4">
	    <thead>
	      <row>
		<entry align="left">Options in /boot.config</entry>
		<entry align="left">Console during boot blocks</entry>
		<entry align="left">Console during boot loader</entry>
		<entry align="left">Console in kernel</entry>
	      </row>
	    </thead>

	    <tbody>
	      <row>
		<entry>nothing</entry>
		<entry>internal</entry>
		<entry>internal</entry>
		<entry>internal</entry>
	      </row>

	      <row>
		<entry><option>-h</option></entry>
		<entry>serial</entry>
		<entry>serial</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-D</option></entry>
		<entry>serial and internal</entry>
		<entry>internal</entry>
		<entry>internal</entry>
	      </row>

	      <row>
		<entry><option>-Dh</option></entry>
		<entry>serial and internal</entry>
		<entry>serial</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-P</option>, keyboard present</entry>
		<entry>internal</entry>
		<entry>internal</entry>
		<entry>internal</entry>
	      </row>

	      <row>
		<entry><option>-P</option>, keyboard absent</entry>
		<entry>serial and internal</entry>
		<entry>serial</entry>
		<entry>serial</entry>
	      </row>
	    </tbody>
	  </tgroup>
	</informaltable>
      </sect3>

      <sect3>
	<title>Case 2: You Set the Flags to 0x30 for sio0</title>

	<programlisting>device sio0 at isa? port IO_COM1 flags 0x30 irq 4</programlisting>

	<informaltable frame="none" pgwide="1">
	  <tgroup cols="4">
	    <thead>
	      <row>
		<entry align="left">Options in /boot.config</entry>
		<entry align="left">Console during boot blocks</entry>
		<entry align="left">Console during boot loader</entry>
		<entry align="left">Console in kernel</entry>
	      </row>
	    </thead>

	    <tbody>
	      <row>
		<entry>nothing</entry>
		<entry>internal</entry>
		<entry>internal</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-h</option></entry>
		<entry>serial</entry>
		<entry>serial</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-D</option></entry>
		<entry>serial and internal</entry>
		<entry>internal</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-Dh</option></entry>
		<entry>serial and internal</entry>
		<entry>serial</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-P</option>, keyboard present</entry>
		<entry>internal</entry>
		<entry>internal</entry>
		<entry>serial</entry>
	      </row>

	      <row>
		<entry><option>-P</option>, keyboard absent</entry>
		<entry>serial and internal</entry>
		<entry>serial</entry>
		<entry>serial</entry>
	      </row>
	    </tbody>
	  </tgroup>
	</informaltable>
      </sect3>
    </sect2>

    <sect2 id="serialconsole-tips">
      <title>Tips for the Serial Console</title>

      <sect3>
	<title>Setting a Faster Serial Port Speed</title>

	<para>By default, the serial port settings are: 9600 baud, 8
	  bits, no parity, and 1 stop bit.  If you wish to change the speed, you
	  need to recompile at least the boot blocks.  Add the following line
	  to <filename>/etc/make.conf</filename> and compile new boot
	  blocks:</para>

	<programlisting>BOOT_COMCONSOLE_SPEED=19200</programlisting>

	<para>See <xref linkend="serialconsole-com2"/> for detailed
	  instructions about building and installing new boot blocks.</para>

	<para>If the serial console is configured in some other way than by
	  booting with <option>-h</option>, or if the serial console used by
	  the kernel is different from the one used by the boot blocks, then
	  you must also add the following option to the kernel configuration
	  file and compile a new kernel:</para>

	<programlisting>options CONSPEED=19200</programlisting>
      </sect3>

      <sect3 id="serialconsole-com2">
	<title>Using Serial Port Other Than <devicename>sio0</devicename> for
	  the Console</title>

	<para>Using a port other than <devicename>sio0</devicename> as the
	  console requires some recompiling.  If you want to use another
	  serial port for whatever reasons, recompile the boot blocks, the
	  boot loader and the kernel as follows.</para>

	<procedure>
	  <step>
	    <para>Get the kernel source. (See <xref linkend="cutting-edge"/>)</para>
	  </step>

	  <step>
	    <para>Edit <filename>/etc/make.conf</filename> and set
	      <literal>BOOT_COMCONSOLE_PORT</literal> to the address of the
	      port you want to use (0x3F8, 0x2F8, 0x3E8 or 0x2E8).  Only
	      <devicename>sio0</devicename> through
	      <devicename>sio3</devicename> (<devicename>COM1</devicename>
	      through <devicename>COM4</devicename>) can be used;  multiport
	      serial cards will not work.  No interrupt setting is
	      needed.</para>
	  </step>

	  <step>
	    <para>Create a custom kernel configuration file and add
	      appropriate flags for the serial port you want to use. For
	      example, if you want to make <devicename>sio1</devicename>
	      (<devicename>COM2</devicename>) the console:</para>

	    <programlisting>device sio1 at isa? port IO_COM2 flags 0x10 irq 3</programlisting>

	    <para>or</para>

	    <programlisting>device sio1 at isa? port IO_COM2 flags 0x30 irq 3</programlisting>

	    <para>The console flags for the other serial ports should not be
	      set.</para>
	  </step>

	  <step>
	    <para>Recompile and install the boot blocks and the boot loader:</para>

	    <screen>&prompt.root; <userinput>cd /sys/boot</userinput>
&prompt.root; <userinput>make clean</userinput>
&prompt.root; <userinput>make</userinput>
&prompt.root; <userinput>make install</userinput></screen>
	  </step>

	  <step>
	    <para>Rebuild and install the kernel.</para>
	  </step>

	  <step>
	    <para>Write the boot blocks to the boot disk with
		&man.disklabel.8; and boot from the new kernel.</para>
	  </step>
	</procedure>
      </sect3>

      <sect3 id="serialconsole-ddb">
	<title>Entering the DDB Debugger from the Serial Line</title>

	<para>If you wish to drop into the kernel debugger from the serial
	  console (useful for remote diagnostics, but also dangerous if you
	  generate a spurious BREAK on the serial port!) then you should
	  compile your kernel with the following options:</para>

	<programlisting>options BREAK_TO_DEBUGGER
options DDB</programlisting>
      </sect3>

      <sect3>
	<title>Getting a Login Prompt on the Serial Console</title>

	<para>While this is not required, you may wish to get a
	  <emphasis>login</emphasis> prompt over the serial line, now that you
	  can see boot messages and can enter the kernel debugging session
	  through the serial console.  Here is how to do it.</para>

	<para>Open the file <filename>/etc/ttys</filename> with an editor
	  and locate the lines:</para>

      <programlisting>ttyd0 "/usr/libexec/getty std.9600" unknown off secure
ttyd1 "/usr/libexec/getty std.9600" unknown off secure
ttyd2 "/usr/libexec/getty std.9600" unknown off secure
ttyd3 "/usr/libexec/getty std.9600" unknown off secure</programlisting>

	<para><literal>ttyd0</literal> through <literal>ttyd3</literal>
	  corresponds to <devicename>COM1</devicename> through
	  <devicename>COM4</devicename>.  Change <literal>off</literal> to
	  <literal>on</literal> for the desired port.  If you have changed the
	  speed of the serial port, you need to change
	  <literal>std.9600</literal> to match the current setting, e.g.
	  <literal>std.19200</literal>.</para>

	<para>You may also want to change the terminal type from
	  <literal>unknown</literal> to the actual type of your serial
	  terminal.</para>

	<para>After editing the file, you must <command>kill -HUP 1</command>
	  to make this change take effect.</para>
      </sect3>
    </sect2>

    <sect2 id="serialconsole-loader">
      <title>Changing Console from the Boot Loader</title>

      <para>Previous sections described how to set up the serial console by
	tweaking the boot block.  This section shows that you can specify the
	console by entering some commands and environment variables in the
	boot loader.  As the boot loader is invoked at the third stage of the
	boot process, after the boot block, the settings in the boot loader
	will override the settings in the boot block.</para>

      <sect3>
	<title>Setting Up the Serial Console</title>

	<para>You can easily specify the boot loader and the kernel to use the
	  serial console by writing just one line in
	  <filename>/boot/loader.rc</filename>:</para>

	<programlisting>set console="comconsole"</programlisting>

	<para>This will take effect regardless of the settings in the boot
	  block discussed in the previous section.</para>

	<para>You had better put the above line as the first line of
	  <filename>/boot/loader.rc</filename> so as to see boot messages  on
	  the serial console as early as possible.</para>

	<para>Likewise, you can specify the internal console as:</para>

	<programlisting>set console="vidconsole"</programlisting>

	<para>If you do not set the boot loader environment variable
	  <envar>console</envar>, the boot loader, and subsequently the
	  kernel, will use whichever console indicated by the
	  <option>-h</option> option in the  boot block.</para>

	<para>In versions 3.2 or later, you may specify the console in
	  <filename>/boot/loader.conf.local</filename> or
	  <filename>/boot/loader.conf</filename>, rather than in
	  <filename>/boot/loader.rc</filename>.  In this method your
	  <filename>/boot/loader.rc</filename> should look like:</para>

	<programlisting>include /boot/loader.4th
start</programlisting>

	<para>Then, create <filename>/boot/loader.conf.local</filename>  and
	  put the following line there.</para>

	<programlisting>console=comconsole</programlisting>

	<para>or</para>

	<programlisting>console=vidconsole</programlisting>

	<para>See &man.loader.conf.5; for more information.</para>

	<note>
	  <para>At the moment, the boot loader has no option equivalent to the
	    <option>-P</option> option in the boot block, and there is no
	    provision to automatically select the internal console and the
	    serial console based on the presence of the keyboard.</para>
	</note>
      </sect3>

      <sect3>
	<title>Using a Serial Port Other Than <devicename>sio0</devicename> for
	  the Console</title>

	<para>You need to recompile the boot loader to use a serial port other
	  than <devicename>sio0</devicename> for the serial console. Follow the
	  procedure described in <xref linkend="serialconsole-com2"/>.</para>
      </sect3>
    </sect2>

    <sect2 id="serialconsole-caveats">
      <title>Caveats</title>

      <para>The idea here is to allow people to set up dedicated servers  that
	require no graphics hardware or attached keyboards.  Unfortunately,
	while most systems will let you boot without a keyboard, there
	are quite a few that will not let you boot without a graphics adapter.
	Machines with AMI BIOSes can be configured to  boot with no graphics
	adapter installed simply by changing the <quote>graphics adapter</quote> setting in
	the CMOS configuration to <quote>Not installed.</quote></para>

      <para>However, many machines do not support this option and will refuse
	to boot if you have no display hardware in the system.  With these
	machines, you will have to leave some kind of graphics card plugged in,
	(even if it is just a junky mono board) although you will not have to
	attach a monitor. You might also try installing an AMI
	BIOS.</para>
    </sect2>
  </sect1>
</chapter>