/usr/share/doc/samhain/manual.html/chroot.html

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><A
NAME="CHROOT"
>6.9. Chroot</A
></H1
><P
>As of version 1.7.0, <SPAN
CLASS="APPLICATION"
>yule</SPAN
>is able to chroot
itself after startup and initialization, either by using the
command line option</P
><PRE
CLASS="SCREEN"
><SAMP
CLASS="PROMPT"
>bash$</SAMP
><KBD
CLASS="USERINPUT"
> yule --chroot=<TT
CLASS="REPLACEABLE"
><I
>/chrootdir</I
></TT
></KBD
></PRE
><P
>or by requesting it in the configuration file:</P
><PRE
CLASS="PROGRAMLISTING"
>[Misc]
<B
CLASS="COMMAND"
>SetChrootDir=<TT
CLASS="REPLACEABLE"
><I
>path</I
></TT
></B
></PRE
><P
>In order to prepare for the chroot jail, the following is required:</P
><DIV
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><B
>Tip</B
></TH
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><TR
><TD
>&nbsp;</TD
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><P
>In the <TT
CLASS="FILENAME"
>scripts</TT
> subdirectory
of the source directory there is a script <TT
CLASS="FILENAME"
>chroot.sh</TT
>
to perform steps (4) and (5) (only for Linux).</P
></TD
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><P
><P
></P
><OL
TYPE="1"
><LI
><P
>    Compile normally. Make sure you use either <TT
CLASS="FILENAME"
>dev/random</TT
>
    (default if existing) or EGD (Entropy Gathering Daemon) for the 
    entropy device. If <TT
CLASS="FILENAME"
>dev/random</TT
> does not exist,
    the default is the 'standard unix entropy gatherer', which uses
    the output of many system commands, and therefore is not suitable
    within a chroot jail. 
    </P
></LI
><LI
><P
>    Install with the command(s):
    </P
><PRE
CLASS="SCREEN"
><SAMP
CLASS="PROMPT"
>bash$</SAMP
><KBD
CLASS="USERINPUT"
> make DESTDIR=<TT
CLASS="REPLACEABLE"
><I
>/chrootdir</I
></TT
> install</KBD
>
<SAMP
CLASS="PROMPT"
>bash$</SAMP
><KBD
CLASS="USERINPUT"
> make DESTDIR=<TT
CLASS="REPLACEABLE"
><I
>/chrootdir</I
></TT
> install-user</KBD
>
<SAMP
CLASS="PROMPT"
>bash$</SAMP
><KBD
CLASS="USERINPUT"
> make install-boot</KBD
></PRE
></LI
><LI
><P
>    Fix the path to the <SPAN
CLASS="APPLICATION"
>yule</SPAN
> binary in the
    runlevel start/stop script installed by the last command. 
    </P
></LI
><LI
><P
>    Prepare the chroot environment. Basically, you need under
    <TT
CLASS="FILENAME"
>/chrootdir</TT
>
    </P
><P
> 
    (a) an entropy device,
    either <TT
CLASS="FILENAME"
>dev/random</TT
>, <TT
CLASS="FILENAME"
>dev/urandom</TT
>, 
    or an EGD (Entropy Gathering Daemon) socket, 
    </P
><P
> 
    (b) minimum <TT
CLASS="FILENAME"
>etc/passwd</TT
>, <TT
CLASS="FILENAME"
>etc/group</TT
>
    files, at least with entries for root and the unprivileged 
    <SPAN
CLASS="APPLICATION"
>yule</SPAN
> user. Replace passwords with an asterix,
    and make sure the homedirectory of the unprivileged 
    <SPAN
CLASS="APPLICATION"
>yule</SPAN
> user is correct within the chroot jail.
    </P
><P
> 
    (c) files required for DNS: <TT
CLASS="FILENAME"
>etc/nsswitch.conf</TT
>,
     <TT
CLASS="FILENAME"
>etc/hosts</TT
>, 
     <TT
CLASS="FILENAME"
>etc/host.conf</TT
>,
     <TT
CLASS="FILENAME"
>etc/resolv.conf</TT
>,
     <TT
CLASS="FILENAME"
>etc/services</TT
>,
     <TT
CLASS="FILENAME"
>etc/protocols</TT
>.
     </P
></LI
><LI
><P
>    Create a symlink <TT
CLASS="FILENAME"
>/etc/yulerc</TT
> to 
    <TT
CLASS="FILENAME"
>/chrootdir/etc/yulerc</TT
> (no, it will not work
    the other way round).
    </P
></LI
></OL
></P
><P
>Because <SPAN
CLASS="APPLICATION"
>yule</SPAN
> chroots after startup, there is no
need to copy shared libraries into the chroot jail. They will be loaded
upon startup, before the chroot() occurs.</P
><DIV
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>Tip</B
></TH
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><TR
><TD
>&nbsp;</TD
><TD
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><P
>If you are using syslog logging, you need a <TT
CLASS="FILENAME"
>dev/log</TT
>
socket in the chroot jail. Modern <SPAN
CLASS="APPLICATION"
>syslog</SPAN
>
incarnations will allow you to have an additional socket using the command:</P
><PRE
CLASS="SCREEN"
><SAMP
CLASS="PROMPT"
>bash$</SAMP
><KBD
CLASS="USERINPUT"
> syslogd -a <TT
CLASS="REPLACEABLE"
><I
>/chrootdir</I
></TT
>/dev/log</KBD
></PRE
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><B
>Tip</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>If you are using a GnuPG-signed configuration, you will need a working
copy of <SPAN
CLASS="APPLICATION"
>gpg</SPAN
> in the chroot jail.</P
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samhain 3.1.0-5ubuntu1 / usr / share / doc / samhain / manual.html / chroot.html
