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<article xmlns="http://docbook.org/ns/docbook"
  xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
  xml:lang="en"> <info>
    <title>FreeBSD Quickstart Guide for &linux; Users</title>

    <authorgroup>
      <author><personname><firstname>John</firstname><surname>Ferrell</surname></personname></author>
    </authorgroup>

    <copyright>
      <year>2008</year>
      <holder>The FreeBSD Documentation Project</holder>
    </copyright>

    <pubdate>$FreeBSD$</pubdate>

    <releaseinfo>$FreeBSD$</releaseinfo>

    <legalnotice xml:id="trademarks" role="trademarks">
      &tm-attrib.freebsd;
      &tm-attrib.linux;
      &tm-attrib.intel;
      &tm-attrib.redhat;
      &tm-attrib.unix;
      &tm-attrib.general;
    </legalnotice>

    <abstract>
      <para>This document is intended to quickly familiarize
	intermediate to advanced &linux; users with the basics of
	&os;.</para>
    </abstract>
  </info>

  <sect1 xml:id="intro">
    <title>Introduction</title>

    <para>This document highlights some of the technical differences
      between &os; and &linux; so that intermediate to advanced
      &linux; users can quickly familiarize themselves with the basics
      of &os;.</para>

    <para>This document assumes that &os; is already installed.  Refer
      to the <link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/bsdinstall.html">
      Installing &os;</link> chapter of the &os;&nbsp;Handbook for
      help with the installation process.</para>
  </sect1>

  <sect1 xml:id="shells">
    <title>Default Shell</title>

    <para>&linux; users are often surprised to find that
      <application>Bash</application> is not the default shell in
      &os;.  In fact, <application>Bash</application> is not included
      in the default installation.  Instead, &os; uses &man.tcsh.1; as
      the default root shell, and the <application>Bourne
	shell</application>-compatible &man.sh.1; as the default user
      shell.  &man.sh.1; is very similar to
      <application>Bash</application> but with a much smaller
      feature-set.  Generally shell scripts written for &man.sh.1;
      will run in <application>Bash</application>, but the reverse is
      not always true.</para>

    <para>However, <application>Bash</application> and other shells
      are available for installation using the &os; <link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports.html">Packages
	and Ports Collection</link>.</para>

    <para>After installing another shell, use &man.chsh.1; to change a
      user's default shell.  It is recommended that the <systemitem
	class="username">root</systemitem> user's default shell remain
      unchanged since shells which are not included in the base
      distribution are installed to
      <filename>/usr/local/bin</filename>.  In the event of a problem,
      the file system where <filename>/usr/local/bin</filename> is
      located may not be mounted.  In this case, <systemitem
	class="username">root</systemitem> would not have access to
      its default  shell, preventing <systemitem
	class="username">root</systemitem> from logging in and fixing
      the problem.</para>
  </sect1>

  <sect1 xml:id="software">
    <title>Packages and Ports: Adding Software in &os;</title>

    <para>&os; provides two methods for installing applications:
      binary packages and compiled ports.  Each method has its own
      benefits:</para>

    <itemizedlist>
      <title>Binary Packages</title>

      <listitem>
	<simpara>Faster installation as compared to
	compiling large applications.</simpara>
      </listitem>

      <listitem>
	<simpara>Does not require an understanding of how to
	compile software.</simpara>
      </listitem>

      <listitem>
	<simpara>No need to install a compiler.</simpara>
      </listitem>
    </itemizedlist>

    <itemizedlist>
      <title>Ports</title>

      <listitem>
	<simpara>Ability to customize installation options.</simpara>
      </listitem>

      <listitem>
	<simpara>Custom patches can be applied.</simpara>
      </listitem>
    </itemizedlist>

    <para>If an application installation does not require any
      customization, installing the package is sufficient.  Compile
      the port instead whenever an application requires customization
      of the default options.  If needed, a custom package can be
      compiled from ports using <command>make</command>
      <buildtarget>package</buildtarget>.</para>

    <para>A complete list of all available ports and packages can
      be found <link
	xlink:href="https://www.freebsd.org/ports/master-index.html">here</link>.</para>

    <sect2 xml:id="packages">
      <title>Packages</title>

      <para>Packages are pre-compiled applications, the &os;
	equivalents of <filename>.deb</filename> files on
	Debian/Ubuntu based systems and <filename>.rpm</filename>
	files on Red&nbsp;Hat/Fedora based systems.  Packages are
	installed using <command>pkg</command>.  For example,
	the following command installs
	<application>Apache 2.4</application>:</para>

      <screen>&prompt.root; <userinput>pkg install <replaceable>apache24</replaceable></userinput></screen>

      <para>For more information on packages refer to section 5.4 of
	the &os; Handbook: <link
	  xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/pkgng-intro.html">Using
	  pkgng for Binary Package Management</link>.</para>
    </sect2>

    <sect2 xml:id="ports">
      <title>Ports</title>

      <para>The &os; Ports Collection is a framework of
	<filename>Makefiles</filename> and patches specifically
	customized for installing applications from source on &os;.
	When installing a port, the system will fetch the source code,
	apply any required patches, compile the code, and install the
	application and any required dependencies.</para>

      <para>The Ports Collection, sometimes referred to as the ports
	tree, can be installed to <filename>/usr/ports</filename>
	using &man.portsnap.8;.  Detailed instructions for installing
	the Ports Collection can be found in <link
	  xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports-using.html">section
	  5.5</link> of the &os; Handbook.</para>

      <para>To compile a port, change to the port's directory and
	start the build process.  The following example installs
	<application>Apache 2.4</application> from the Ports
	Collection:</para>

      <screen>&prompt.root; <userinput>cd /usr/ports/www/apache24</userinput>
&prompt.root; <userinput>make install clean</userinput></screen>

      <para>A benefit of using ports to install software is the
	ability to customize the installation options.  This example
	specifies that the <application>mod_ldap</application> module
	should also be installed:</para>

      <screen>&prompt.root; <userinput>cd /usr/ports/www/apache24</userinput>
&prompt.root; <userinput>make WITH_LDAP="YES" install clean</userinput></screen>

      <para>Refer to <link
	  xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports-using.html">Using
	  the Ports Collection</link> for more information.</para>
    </sect2>
  </sect1>

  <sect1 xml:id="startup">
    <title>System Startup</title>

    <para>Many &linux; distributions use the SysV init system, whereas
      &os; uses the traditional BSD-style &man.init.8;.  Under the
      BSD-style &man.init.8;, there are no run-levels and
      <filename>/etc/inittab</filename> does not exist.  Instead,
      startup is controlled by &man.rc.8; scripts.  At system boot,
      <filename>/etc/rc</filename> reads
      <filename>/etc/rc.conf</filename> and
      <filename>/etc/defaults/rc.conf</filename>
      to determine which services are to be started.  The specified
      services are then started by running the corresponding service
      initialization scripts located in
      <filename>/etc/rc.d/</filename> and
      <filename>/usr/local/etc/rc.d/</filename>.  These scripts are
      similar to the scripts located in
      <filename>/etc/init.d/</filename> on &linux; systems.</para>

    <para>The scripts found in <filename>/etc/rc.d/</filename> are for
      applications that are part of the <quote>base</quote> system,
      such as &man.cron.8;, &man.sshd.8;, and &man.syslog.3;.  The
      scripts in <filename>/usr/local/etc/rc.d/</filename> are for
      user-installed applications such as
      <application>Apache</application> and
      <application>Squid</application>.</para>

    <para>Since &os; is developed as a complete operating system,
      user-installed applications are not considered to be part of
      the <quote>base</quote> system.  User-installed applications
      are generally installed using <link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports-using.html">Packages
	or Ports</link>.  In order to keep them separate from the base
      system, user-installed applications are installed under
      <filename>/usr/local/</filename>.  Therefore, user-installed
      binaries reside in <filename>/usr/local/bin/</filename>,
      configuration files are in <filename>/usr/local/etc/</filename>,
      and so on.</para>

    <para>Services are enabled by adding an entry for the service in
      <filename>/etc/rc.conf</filename> .  The system defaults are
      found in <filename>/etc/defaults/rc.conf</filename> and these
      default settings are overridden by settings in
      <filename>/etc/rc.conf</filename>.  Refer to &man.rc.conf.5; for
      more information about the available entries.  When installing
      additional applications, review the application's install
      message to determine how to enable any associated
      services.</para>

    <para>The following entries in <filename>/etc/rc.conf</filename>
      enable &man.sshd.8;, enable <application>Apache
	2.4</application>, and specify that
      <application>Apache</application> should be started with
      <acronym>SSL</acronym>.</para>

    <programlisting># enable SSHD
sshd_enable="YES"
# enable Apache with SSL
apache24_enable="YES"
apache24_flags="-DSSL"</programlisting>

    <para>Once a service has been enabled in
      <filename>/etc/rc.conf</filename>, it can be started without
      rebooting the system:</para>

    <screen>&prompt.root; <userinput>service <replaceable>sshd</replaceable> start</userinput>
&prompt.root; <userinput>service <replaceable>apache24</replaceable> start</userinput></screen>

    <para>If a service has not been enabled, it can be started from
      the command line using <option>onestart</option>:</para>

    <screen>&prompt.root; <userinput>service <replaceable>sshd</replaceable> onestart</userinput></screen>
  </sect1>

  <sect1 xml:id="network">
    <title>Network Configuration</title>

    <para>Instead of a generic <emphasis>ethX</emphasis> identifier
      that &linux; uses to identify a network interface, &os; uses the
      driver name followed by a number.  The following output from
      &man.ifconfig.8; shows two &intel;&nbsp;Pro&nbsp;1000 network
      interfaces (<filename>em0</filename> and
      <filename>em1</filename>):</para>

    <screen>&prompt.user; <userinput>ifconfig</userinput>
em0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
        options=b&lt;RXCSUM,TXCSUM,VLAN_MTU&gt;
        inet 10.10.10.100 netmask 0xffffff00 broadcast 10.10.10.255
        ether 00:50:56:a7:70:b2
        media: Ethernet autoselect (1000baseTX &lt;full-duplex&gt;)
        status: active
em1: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
        options=b&lt;RXCSUM,TXCSUM,VLAN_MTU&gt;
        inet 192.168.10.222 netmask 0xffffff00 broadcast 192.168.10.255
        ether 00:50:56:a7:03:2b
        media: Ethernet autoselect (1000baseTX &lt;full-duplex&gt;)
        status: active</screen>

    <para>An <acronym>IP</acronym> address can be assigned to an
      interface using &man.ifconfig.8;.  To remain persistent across
      reboots, the <acronym>IP</acronym> configuration must be
      included in <filename>/etc/rc.conf</filename>.  The following
      <filename>/etc/rc.conf</filename> entries specify the hostname,
      <acronym>IP</acronym> address, and default gateway:</para>

    <programlisting>hostname="server1.example.com"
ifconfig_em0="inet 10.10.10.100 netmask 255.255.255.0"
defaultrouter="10.10.10.1"</programlisting>

    <para>Use the following entries to instead configure an interface
      for <acronym>DHCP</acronym>:</para>

    <programlisting>hostname="server1.example.com"
ifconfig_em0="DHCP"</programlisting>
  </sect1>

  <sect1 xml:id="firewall">
    <title>Firewall</title>

    <para>&os; does not use  &linux;
      <application>IPTABLES</application> for its firewall.  Instead,
      &os; offers a choice of three kernel level firewalls:</para>

    <itemizedlist>
      <listitem>
	<simpara><link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/firewalls-pf.html">PF</link></simpara>
      </listitem>
      <listitem>
	<simpara><link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/firewalls-ipf.html">IPFILTER</link></simpara>
      </listitem>
      <listitem>
	<simpara><link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/firewalls-ipfw.html">IPFW</link></simpara>
      </listitem>
    </itemizedlist>

    <para><application>PF</application> is developed by the OpenBSD
      project and ported to &os;.  <application>PF</application> was
      created as a replacement for <application>IPFILTER</application>
      and its syntax is similar to that of
      <application>IPFILTER</application>.
      <application>PF</application> can be paired with &man.altq.4; to
      provide <acronym>QoS</acronym> features.</para>

    <para>This sample <application>PF</application> entry allows
      inbound <application>SSH</application>:</para>

    <programlisting>pass in on $ext_if inet proto tcp from any to ($ext_if) port 22</programlisting>

    <para><application>IPFILTER</application> is the firewall
      application developed by Darren Reed.  It is not specific to
      &os; and has been ported to several operating systems including
      NetBSD, OpenBSD, SunOS, HP/UX, and Solaris.</para>

    <para>The <application>IPFILTER</application> syntax to allow
      inbound <application>SSH</application> is:</para>

    <programlisting>pass in on $ext_if proto tcp from any to any port = 22</programlisting>

    <para><application>IPFW</application> is the firewall developed
      and maintained by &os;.  It can be paired with &man.dummynet.4;
      to provide traffic shaping capabilities and simulate different
      types of network connections.</para>

    <para>The <application>IPFW</application> syntax to allow inbound
      <application>SSH</application> would be:</para>

    <programlisting>ipfw add allow tcp from any to me 22 in via $ext_if</programlisting>
  </sect1>

  <sect1 xml:id="updates">
    <title>Updating &os;</title>

    <para>There are two methods for updating a &os; system: from
      source or binary updates.</para>

    <para>Updating from source is the most involved update method, but
      offers the greatest amount of flexibility.  The process involves
      synchronizing a local copy of the &os; source code with the &os;
      <application>Subversion</application> servers.  Once the local
      source code is up-to-date, a new version of the kernel and
      userland can be compiled.</para>

    <para>Binary updates are similar to using <command>yum</command>
      or <command>apt-get</command> to update a &linux; system.  In
      &os;, &man.freebsd-update.8; can be used fetch new binary
      updates and install them.  These updates can be scheduled using
      &man.cron.8;.</para>

    <note>
      <para>When using &man.cron.8; to schedule updates, use
	<command>freebsd-update cron</command> in the &man.crontab.1;
	to reduce the possibility of a large number of machines all
	pulling updates at the same time:</para>

      <programlisting>0 3 * * * root /usr/sbin/freebsd-update cron</programlisting>
    </note>

    <para>For more information on source and binary updates, refer to
      <link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/updating-upgrading.html">the
	chapter on updating</link> in the &os; Handbook.</para>
  </sect1>

  <sect1 xml:id="procfs">
    <title>procfs: Gone But Not Forgotten</title>

    <para>In some &linux; distributions, one could look at
      <filename>/proc/sys/net/ipv4/ip_forward</filename> to determine
      if <acronym>IP</acronym> forwarding is enabled.  In &os;,
      &man.sysctl.8; is instead used to view this and other system
      settings.</para>

    <para>For example, use the following to determine if
      <acronym>IP</acronym> forwarding is enabled on a &os;
      system:</para>

    <screen>&prompt.user; <userinput>sysctl net.inet.ip.forwarding</userinput>
net.inet.ip.forwarding: 0</screen>

    <para>Use <option>-a</option> to list all the system
      settings:</para>

    <screen>&prompt.user; <userinput>sysctl -a | more</userinput></screen>

    <para>If an application requires procfs, add the following entry
      to <filename>/etc/fstab</filename>:</para>

    <screen>proc                /proc           procfs  rw,noauto       0       0</screen>

    <para>Including <option>noauto</option> will prevent
      <filename>/proc</filename> from being automatically mounted at
      boot.</para>

    <para>To mount the file system without rebooting:</para>

    <screen>&prompt.root; <userinput>mount /proc</userinput></screen>
  </sect1>

  <sect1 xml:id="commands">
    <title>Common Commands</title>

    <para>Some common command equivalents are as follows:</para>

    <para><informaltable frame="none" pgwide="1">
	<tgroup cols="3">
	  <thead>
	    <row>
	      <entry>&linux; command (Red&nbsp;Hat/Debian)</entry>
	      <entry>&os; equivalent</entry>
	      <entry>Purpose</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry><command>yum install
		  <replaceable>package</replaceable></command> /
		<command>apt-get install
		  <replaceable>package</replaceable></command></entry>
	      <entry><command>pkg install
		  <replaceable>package</replaceable></command></entry>
	      <entry>Install package from remote repository</entry>
	    </row>

	    <row>
	      <entry><command>rpm -ivh
		  <replaceable>package</replaceable></command> /
		<command>dpkg -i
		  <replaceable>package</replaceable></command></entry>
	      <entry><command>pkg add
		  <replaceable>package</replaceable></command></entry>
	      <entry>Install local package</entry>
	    </row>

	    <row>
	      <entry><command>rpm -qa</command>
		/ <command>dpkg -l</command></entry>
	      <entry><command>pkg info</command></entry>
	      <entry>List installed packages</entry>
	    </row>

	    <row>
	      <entry><command>lspci</command></entry>
	      <entry><command>pciconf</command></entry>
	      <entry>List <acronym>PCI</acronym> devices</entry>
	    </row>

	    <row>
	      <entry><command>lsmod</command></entry>
	      <entry><command>kldstat</command></entry>
	      <entry>List loaded kernel modules</entry>
	    </row>

	    <row>
	      <entry><command>modprobe</command></entry>
	      <entry><command>kldload</command>
		/ <command>kldunload</command></entry>
	      <entry>Load/Unload kernel modules</entry>
	    </row>

	    <row>
	      <entry><command>strace</command></entry>
	      <entry><command>truss</command></entry>
	      <entry>Trace system calls</entry>
	    </row>
	  </tbody>
	</tgroup>
      </informaltable></para>
  </sect1>

  <sect1 xml:id="conclusion">
    <title>Conclusion</title>

    <para>This document has provided an overview of &os;.   Refer to
      the <link
	xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/index.html">&os;&nbsp;Handbook</link>
      for more in-depth coverage of these topics as well as the many
      topics not covered by this document.</para>
  </sect1>
</article>