source: BOOK/bootscripts/common/network.xml@ 1a498b5

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  "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
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<sect1 id="ch-scripts-network">
  <?dbhtml filename="network.html"?>

  <title>Configuring the network Script</title>

  <indexterm zone="ch-scripts-network">
    <primary sortas="d-network">network</primary>
  <secondary>configuring</secondary></indexterm>

  <para>This section only applies if a network card is to be
  configured.</para>

  <para>If a network card will not be used, there is likely no need to
  create any configuration files relating to network cards. If that is
  the case, remove the <filename class="symlink">network</filename>
  symlinks from all run-level directories (<filename
  class="directory">/etc/rc.d/rc*.d</filename>).</para>

  <sect2>
    <title>Creating Network Interface Configuration Files</title>

    <para>Which interfaces are brought up and down by the network script
    depends on the files and directories in the <filename
    class="directory">/etc/sysconfig/network-devices</filename> hierarchy.
    This directory should contain a sub-directory for each interface to be
    configured, such as <filename>ifconfig.xyz</filename>, where
    <quote>xyz</quote> is a network interface name. Inside this directory
    would be files defining the attributes to this interface, such as its
    IP address(es), subnet masks, and so forth.</para>

    <para>The following command creates a sample <filename>ipv4</filename>
    file for the <filename class="devicefile">eth0</filename> device:</para>

<screen><userinput>cd /etc/sysconfig/network-devices &amp;&amp;
mkdir -v ifconfig.eth0 &amp;&amp;
cat &gt; ifconfig.eth0/ipv4 &lt;&lt; "EOF"
<literal>ONBOOT=yes
SERVICE=ipv4-static
IP=192.168.1.1
GATEWAY=192.168.1.2
PREFIX=24
BROADCAST=192.168.1.255</literal>
EOF</userinput></screen>

    <para>The values of these variables must be changed in every file to
    match the proper setup. If the <envar>ONBOOT</envar> variable is
    set to <quote>yes</quote> the network script will bring up the
    Network Interface Card (NIC) during booting of the system. If set
    to anything but <quote>yes</quote> the NIC will be ignored by the
    network script and not brought up.</para>

    <para>The <envar>SERVICE</envar> variable defines the method used for
    obtaining the IP address. The CLFS-Bootscripts package has a modular IP
    assignment format, and creating additional files in the <filename
    class="directory">/etc/sysconfig/network-devices/services</filename>
    directory allows other IP assignment methods. This is commonly used
    for Dynamic Host Configuration Protocol (DHCP), which is addressed in
    the BLFS book.</para>

    <para>The <envar>GATEWAY</envar> variable should contain the default
    gateway IP address, if one is present. If not, then comment out the
    variable entirely.</para>

    <para>The <envar>PREFIX</envar> variable needs to contain the number
    of bits used in the subnet. Each octet in an IP address is 8 bits.
    If the subnet's netmask is 255.255.255.0, then it is using the first
    three octets (24 bits) to specify the network number. If the netmask
    is 255.255.255.240, it would be using the first 28 bits. Prefixes
    longer than 24 bits are commonly used by DSL and cable-based Internet
    Service Providers (ISPs). In this example (PREFIX=24), the netmask is
    255.255.255.0. Adjust the <envar>PREFIX</envar> variable according to
    your specific subnet.</para>

  </sect2>

  <sect2 id="resolv.conf">
    <title>Creating the /etc/resolv.conf File</title>

    <indexterm zone="resolv.conf">
      <primary sortas="e-/etc/resolv.conf">/etc/resolv.conf</primary>
    </indexterm>

    <para>If the system is going to be connected to the Internet, it will
    need some means of Domain Name Service (DNS) name resolution to resolve
    Internet domain names to IP addresses, and vice versa. This is best
    achieved by placing the IP address of the DNS server, available from
    the ISP or network administrator, into <filename>/etc/resolv.conf</filename>.
    Create the file by running the following:</para>

<screen><userinput>cat &gt; /etc/resolv.conf &lt;&lt; "EOF"
<literal># Begin /etc/resolv.conf

domain {<replaceable>[Your Domain Name]</replaceable>}
nameserver <replaceable>[IP address of your primary nameserver]</replaceable>
nameserver <replaceable>[IP address of your secondary nameserver]</replaceable>

# End /etc/resolv.conf</literal>
EOF</userinput></screen>

    <para>Replace <replaceable>[IP address of the nameserver]</replaceable>
    with the IP address of the DNS most appropriate for the setup. There will
    often be more than one entry (requirements demand secondary servers for
    fallback capability). If you only need or want one DNS server, remove the
    second <emphasis>nameserver</emphasis> line from the file. The IP address
    may also be a router on the local network.</para>

  </sect2>

</sect1>