lfs-book/chapter07/network.xml

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<sect1 id="ch-scripts-network">
<title>Configuring the network script</title>
<?dbhtml filename="network.html"?>

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

<para>This section only applies if you're going to configure a network
card.</para>

<para>If you don't have any network cards, you are most likely not going to
create any configuration files relating to network cards. If that is the
case, you must remove the <filename class="symlink">network</filename> symlinks from all the
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 in the <filename class="directory">/etc/sysconfig/network-devices</filename> directory. This
directory should contain subdirectories in the form of
<filename>ifconfig.xyz</filename>, where <quote>xyz</quote> is a network
interface name (such as eth0)</para>

<para>If you decide to rename or move this
<filename class="directory">/etc/sysconfig/network-devices</filename> directory,
make sure you update the <filename>/etc/sysconfig/rc</filename> file as well and
update the <quote>network_devices</quote> by providing it with the new path.</para>

<para>Now, new files are created in that directory.  The following command
creates a sample <filename>ipv4</filename> file for the
<filename>eth0</filename> device:</para>

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

<para>Of course, the values of those variables have to be changed in every file
to match the proper setup. If the ONBOOT variable is set to <quote>yes</quote>,
the network script will bring up the equivalent interface during the booting of
the system.  If set to anything but <quote>yes</quote>, the equivalent interface
will be ignored by the network script and not brought up.</para>

<para>The SERVICE entry defines the method of obtaining the IP address.  The LFS
bootscripts have a modular IP assignment format, and by creating additional
files in
<filename class="directory">/etc/sysconfig/network-devices/services</filename>,
you can allow other IP assignment methods.  This would commonly be used if you
need DHCP, which is addressed in the BLFS book.</para>

<para>Of course, GATEWAY should contain the IP of your default gateway, if you
have one. If not, then don't include the GATEWAY line in the configuration
file.</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 you're going to be connected to the Internet then most likely you'll
need some means of DNS name resolution to resolve Internet domain names to IP
addresses. This is best achieved by placing the IP address of your assigned DNS
resolver, available from your ISP (Internet Service Provider) 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"
# Begin /etc/resolv.conf

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

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

<para>Of course, replace
<replaceable>[IP address of your nameserver]</replaceable> with the IP address
of the DNS resolver assigned for your use. There will often be more than one
entry (requirements demand secondary servers for fallback capability). The IP
address may even be a router on your local network.</para>

</sect2>

</sect1>