lfs-book/chapter06/shadowpwd.xml

<sect1 id="ch06-shadow" xreflabel="Shadow">
<title>Installing Shadow-&shadow-version;</title>
<?dbhtml filename="shadow.html" dir="chapter06"?>

<para>The Shadow package contains programs for handling passwords in a secure
way.</para>

<screen>Estimated build time:           &shadow-time;
Estimated required disk space:  &shadow-compsize;</screen>

&aa-shadowpwd-down;
&aa-shadowpwd-dep;

<sect2><title>&nbsp;</title><para>&nbsp;</para></sect2>

<sect2>
<title>Installation of Shadow</title>

<para>Shadow hard-wires the path to the <userinput>passwd</userinput> binary
within the binary itself, but does this the wrong way. If a
<userinput>passwd</userinput> binary is not present before installing Shadow,
the package incorrectly assumes it is going to be located at
<filename>/bin/passwd</filename>, but then installs it in
<filename>/usr/bin/passwd</filename>. This will lead to errors about not finding
<filename>/bin/passwd</filename>. To work around this bug, create a dummy
<filename>passwd</filename> file, so that it gets hard-wired properly:</para>

<screen><userinput>touch /usr/bin/passwd</userinput></screen>

<para>The current Shadow suite has a problem that causes the
<userinput>newgrp</userinput> command to fail.  The following patch (also
appearing in Shadow's CVS code) fixes this problem:</para>

<screen><userinput>patch -Np1 -i ../&shadow-patch;</userinput></screen>

<para>Now prepare Shadow for compilation:</para>

<screen><userinput>./configure --prefix=/usr --libdir=/usr/lib --enable-shared</userinput></screen>

<para>Compile the package:</para>

<screen><userinput>make</userinput></screen>

<para>And install it:</para>

<screen><userinput>make install</userinput></screen>

<para>Shadow uses two files to configure authentication settings for the
system. Install these two config files:</para>

<screen><userinput>cp etc/{limits,login.access} /etc</userinput></screen>

<para>We want to change the password method to enable MD5 passwords which are
theoretically more secure than the default "crypt" method and also allow
password lengths greater than 8 characters. We also need to change the old
<filename class="directory">/var/spool/mail</filename> location for user
mailboxes to the current location at
<filename class="directory">/var/mail</filename>. We do this by changing the
relevant configuration file while copying it to its destination:</para>

<screen><userinput>sed -e 's%/var/spool/mail%/var/mail%' \
&nbsp;&nbsp;&nbsp;&nbsp;-e 's%#MD5_CRYPT_ENAB.no%MD5_CRYPT_ENAB yes%' \
&nbsp;&nbsp;&nbsp;&nbsp;etc/login.defs.linux &gt; /etc/login.defs</userinput></screen>

<note><para>Be extra careful when typing all of the above. It is probably safer
to cut-and-paste it rather than try and type it all in.</para></note>

<para>According to the man page of <userinput>vipw</userinput>, a
<userinput>vigr</userinput> program should exist too. Since the installation
procedure doesn't create this program, create a symlink manually:</para>

<screen><userinput>ln -s vipw /usr/sbin/vigr</userinput></screen>

<para>As the <filename>/bin/vipw</filename> symlink is redundant (and even
pointing to a non-existent file), remove it:</para>

<screen><userinput>rm /bin/vipw</userinput></screen>

<para>Now move the <userinput>sg</userinput> program to its proper place:</para>

<screen><userinput>mv /bin/sg /usr/bin</userinput></screen>

<para>And move Shadow's dynamic libraries to a more appropriate location:</para>

<screen><userinput>mv /usr/lib/lib{shadow,misc}.so.0* /lib</userinput></screen>

<para>As some packages expect to find the just-moved libraries in
<filename>/usr/lib</filename>, create the following symlinks:</para>

<screen><userinput>ln -sf ../../lib/libshadow.so.0 /usr/lib/libshadow.so
ln -sf ../../lib/libmisc.so.0 /usr/lib/libmisc.so</userinput></screen>

<para>The -D option of the <filename>useradd</filename> program requires this
directory for it to work properly:</para>

<screen><userinput>mkdir /etc/default</userinput></screen>

<para>Coreutils has already installed a <userinput>groups</userinput> program
in <filename>/usr/bin</filename>. If you wish, you can remove the one
installed by Shadow:</para>

<screen><userinput>rm /bin/groups</userinput></screen>

</sect2>

&c6-cf-shadowpwd;
&c6-cf-password;

&aa-shadowpwd-shortdesc;
&aa-shadowpwd-desc;

</sect1>