1531 lines
24 KiB
HTML
1531 lines
24 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Encrypted Root Filesystem HOWTO</TITLE
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><META
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NAME="GENERATOR"
|
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"></HEAD
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><BODY
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CLASS="article"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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||
ALINK="#0000FF"
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><DIV
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CLASS="ARTICLE"
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||
><DIV
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||
CLASS="TITLEPAGE"
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><H1
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CLASS="title"
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><A
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NAME="AEN2"
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></A
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>Encrypted Root Filesystem HOWTO</H1
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><H3
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CLASS="author"
|
||
><A
|
||
NAME="AEN4"
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>Christophe Devine</A
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></H3
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><DIV
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CLASS="revhistory"
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><TABLE
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||
WIDTH="100%"
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||
BORDER="0"
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||
><TR
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||
><TH
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||
ALIGN="LEFT"
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||
VALIGN="TOP"
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||
COLSPAN="3"
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||
><B
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||
>Revision History</B
|
||
></TH
|
||
></TR
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||
><TR
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||
><TD
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||
ALIGN="LEFT"
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||
>Revision v1.3</TD
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||
><TD
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||
ALIGN="LEFT"
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||
>2005-03-13</TD
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><TD
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||
ALIGN="LEFT"
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||
>Revised by: cd</TD
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||
></TR
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||
><TR
|
||
><TD
|
||
ALIGN="LEFT"
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||
COLSPAN="3"
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||
>Updated the packages version.</TD
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||
></TR
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||
><TR
|
||
><TD
|
||
ALIGN="LEFT"
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||
>Revision v1.2</TD
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||
><TD
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||
ALIGN="LEFT"
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||
>2004-10-20</TD
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||
><TD
|
||
ALIGN="LEFT"
|
||
>Revised by: cd</TD
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||
></TR
|
||
><TR
|
||
><TD
|
||
ALIGN="LEFT"
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||
COLSPAN="3"
|
||
>Updated the packages version.</TD
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||
></TR
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||
><TR
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||
><TD
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||
ALIGN="LEFT"
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||
>Revision v1.1</TD
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||
><TD
|
||
ALIGN="LEFT"
|
||
>2003-12-01</TD
|
||
><TD
|
||
ALIGN="LEFT"
|
||
>Revised by: cd</TD
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||
></TR
|
||
><TR
|
||
><TD
|
||
ALIGN="LEFT"
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||
COLSPAN="3"
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||
>Added support for GRUB.</TD
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||
></TR
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||
><TR
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||
><TD
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||
ALIGN="LEFT"
|
||
>Revision v1.0</TD
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||
><TD
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||
ALIGN="LEFT"
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||
>2003-09-24</TD
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||
><TD
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||
ALIGN="LEFT"
|
||
>Revised by: cd</TD
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||
></TR
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||
><TR
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||
><TD
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||
ALIGN="LEFT"
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||
COLSPAN="3"
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||
>Initial release, reviewed by LDP.</TD
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||
></TR
|
||
><TR
|
||
><TD
|
||
ALIGN="LEFT"
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||
>Revision v0.9</TD
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||
><TD
|
||
ALIGN="LEFT"
|
||
>2003-09-11</TD
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||
><TD
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||
ALIGN="LEFT"
|
||
>Revised by: cd</TD
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||
></TR
|
||
><TR
|
||
><TD
|
||
ALIGN="LEFT"
|
||
COLSPAN="3"
|
||
>Updated and converted to DocBook XML.</TD
|
||
></TR
|
||
></TABLE
|
||
></DIV
|
||
><DIV
|
||
><DIV
|
||
CLASS="abstract"
|
||
><A
|
||
NAME="AEN7"
|
||
></A
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||
><P
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||
></P
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||
><P
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||
> This document explains how to make your personal data secure
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by encrypting your Linux root filesystem using strong cryptography.
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</P
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||
><P
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||
></P
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||
></DIV
|
||
></DIV
|
||
><DIV
|
||
CLASS="legalnotice"
|
||
><A
|
||
NAME="AEN9"
|
||
></A
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||
><P
|
||
></P
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||
><P
|
||
> This HOWTO is released under the GNU Free Documentation License
|
||
Version 1.2.
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||
</P
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||
><P
|
||
></P
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||
></DIV
|
||
><HR></DIV
|
||
><DIV
|
||
CLASS="TOC"
|
||
><DL
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||
><DT
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||
><B
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||
>Table of Contents</B
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||
></DT
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||
><DT
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||
>1. <A
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||
HREF="#preparing-system"
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||
>Preparing the system</A
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||
></DT
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||
><DD
|
||
><DL
|
||
><DT
|
||
>1.1. <A
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||
HREF="#partition-layout"
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||
>Setting up the partition layout</A
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||
></DT
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||
><DT
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||
>1.2. <A
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||
HREF="#debian-packages"
|
||
>Required packages</A
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||
></DT
|
||
><DT
|
||
>1.3. <A
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||
HREF="#install-kernel-2.4"
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||
>Installing Linux-2.4.29</A
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||
></DT
|
||
><DT
|
||
>1.4. <A
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||
HREF="#install-kernel-2.6"
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||
>Installing Linux-2.6.10</A
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||
></DT
|
||
><DT
|
||
>1.5. <A
|
||
HREF="#install-util-linux"
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||
>Installing util-linux-2.12p</A
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||
></DT
|
||
></DL
|
||
></DD
|
||
><DT
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||
>2. <A
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||
HREF="#encrypt-root-filesystem"
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||
>Creating the encrypted root filesystem</A
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||
></DT
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||
><DT
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||
>3. <A
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||
HREF="#setup-boot-device"
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||
>Setting up the boot device</A
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||
></DT
|
||
><DD
|
||
><DL
|
||
><DT
|
||
>3.1. <A
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||
HREF="#initial-ramdisk"
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||
>Creating the ramdisk</A
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||
></DT
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||
><DT
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||
>3.2. <A
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||
HREF="#bootable-cd"
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||
>Booting from a CD-ROM</A
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||
></DT
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||
><DT
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||
>3.3. <A
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||
HREF="#boot-partition"
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||
>Booting from a HD partition</A
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||
></DT
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||
></DL
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||
></DD
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||
><DT
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||
>4. <A
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||
HREF="#final-steps"
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||
>Final steps</A
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||
></DT
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||
><DT
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||
>5. <A
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||
HREF="#about"
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||
>About this HOWTO</A
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||
></DT
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||
></DL
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||
></DIV
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||
><DIV
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||
CLASS="sect1"
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||
><H1
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||
CLASS="sect1"
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||
><A
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||
NAME="preparing-system"
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||
></A
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||
>1. Preparing the system</H1
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><DIV
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||
CLASS="sect2"
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||
><H2
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||
CLASS="sect2"
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||
><A
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||
NAME="partition-layout"
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||
></A
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||
>1.1. Setting up the partition layout</H2
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||
><P
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||
> Your hard disk (hda) should contain at least three partitions:
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<P
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||
></P
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||
><UL
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||
><LI
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||
><P
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||
> hda1: this small unencrypted partition will ask for
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a password in order to mount the encrypted root filesystem.
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</P
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||
></LI
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||
><LI
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||
><P
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||
> hda2: this partition will contain your encrypted root filesystem;
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make sure it is large enough.
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</P
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||
></LI
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||
><LI
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||
><P
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||
> hda3: this partition holds the current GNU/Linux system.
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</P
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||
></LI
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||
></UL
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||
>
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||
</P
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><P
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||
> At this point, both hda1 and hda2 are unused. hda3 is where your
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Linux distribution is currently installed; /usr and /boot must
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<EM
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>not</EM
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> be separated from this partition.
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</P
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><P
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> Here's an example of what your partition layout might look like:
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</P
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><P
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> <TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="screen"
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># fdisk -l /dev/hda
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Disk /dev/hda: 255 heads, 63 sectors, 2432 cylinders
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Units = cylinders of 16065 * 512 bytes
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Device Boot Start End Blocks Id System
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/dev/hda1 1 1 8001 83 Linux
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/dev/hda2 2 263 2104515 83 Linux
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/dev/hda3 264 525 2104515 83 Linux
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/dev/hda4 526 2047 12225465 83 Linux</PRE
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||
></FONT
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||
></TD
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||
></TR
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||
></TABLE
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||
>
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||
</P
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||
></DIV
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||
><DIV
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||
CLASS="sect2"
|
||
><HR><H2
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||
CLASS="sect2"
|
||
><A
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||
NAME="debian-packages"
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||
></A
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||
>1.2. Required packages</H2
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||
><P
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||
> If you use Debian, the following packages are mandatory:
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</P
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><P
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> <TABLE
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||
BORDER="0"
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||
BGCOLOR="#E0E0E0"
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||
WIDTH="100%"
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||
><TR
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><TD
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><FONT
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||
COLOR="#000000"
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||
><PRE
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||
CLASS="screen"
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>apt-get install gcc make libncurses5-dev patch bzip2 wget</PRE
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||
></FONT
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||
></TD
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||
></TR
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||
></TABLE
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||
>
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</P
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><P
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> To make copy & paste easier, you should also install:
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</P
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><P
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||
> <TABLE
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||
BORDER="0"
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||
BGCOLOR="#E0E0E0"
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||
WIDTH="100%"
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||
><TR
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><TD
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||
><FONT
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||
COLOR="#000000"
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><PRE
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||
CLASS="screen"
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||
>apt-get install lynx gpm</PRE
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||
></FONT
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||
></TD
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||
></TR
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||
></TABLE
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||
>
|
||
</P
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||
></DIV
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||
><DIV
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||
CLASS="sect2"
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||
><HR><H2
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||
CLASS="sect2"
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||
><A
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||
NAME="install-kernel-2.4"
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||
></A
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||
>1.3. Installing Linux-2.4.29</H2
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||
><P
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||
> There are two main projects which add loopback encryption support in the
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kernel: cryptoloop and loop-AES. This howto is based on loop-AES, since it
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features an extremely fast and highly optimized implementation of Rijndael
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in assembly language, and therefore provides maximum performance if
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you have an IA-32 (x86) CPU. Besides, there are some
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<A
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||
HREF="http://groups.google.com/groups?selm=1emrG-1Ck-25%40gated-at.bofh.it"
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||
TARGET="_top"
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>security concerns</A
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||
>
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||
about cryptoloop.
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||
</P
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||
><P
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||
> First of all, download and unpack the loop-AES package:
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</P
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||
><P
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||
> <TABLE
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||
BORDER="0"
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||
BGCOLOR="#E0E0E0"
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||
WIDTH="100%"
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||
><TR
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||
><TD
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||
><FONT
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||
COLOR="#000000"
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||
><PRE
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||
CLASS="screen"
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||
>cd /usr/src
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wget http://loop-aes.sourceforge.net/loop-AES/loop-AES-v3.0b.tar.bz2
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tar -xvjf loop-AES-v3.0b.tar.bz2</PRE
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||
></FONT
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||
></TD
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||
></TR
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||
></TABLE
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||
>
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||
</P
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||
><P
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||
> Then you must download and patch the kernel source:
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</P
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||
><P
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||
> <TABLE
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||
BORDER="0"
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||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
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||
><TR
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><TD
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><FONT
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||
COLOR="#000000"
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||
><PRE
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CLASS="screen"
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||
>wget http://ftp.kernel.org/pub/linux/kernel/v2.4/linux-2.4.29.tar.bz2
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tar -xvjf linux-2.4.29.tar.bz2
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cd linux-2.4.29
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rm include/linux/loop.h drivers/block/loop.c
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patch -Np1 -i ../loop-AES-v3.0b/kernel-2.4.28.diff</PRE
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||
></FONT
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||
></TD
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||
></TR
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||
></TABLE
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||
>
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||
</P
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||
><P
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> Setup the keyboard map:
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</P
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||
><P
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||
> <TABLE
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||
BORDER="0"
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||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
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||
><TD
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||
><FONT
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||
COLOR="#000000"
|
||
><PRE
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||
CLASS="screen"
|
||
>dumpkeys | loadkeys -m - > drivers/char/defkeymap.c</PRE
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||
></FONT
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||
></TD
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||
></TR
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||
></TABLE
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||
>
|
||
</P
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||
><P
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> Next, configure your kernel; make sure the following options are set:
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</P
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||
><P
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||
> <TABLE
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||
BORDER="0"
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||
BGCOLOR="#E0E0E0"
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||
WIDTH="100%"
|
||
><TR
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||
><TD
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||
><FONT
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||
COLOR="#000000"
|
||
><PRE
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||
CLASS="screen"
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||
>make menuconfig
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||
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||
Block devices --->
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||
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||
<*> Loopback device support
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[*] AES encrypted loop device support (NEW)
|
||
|
||
<*> RAM disk support
|
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(4096) Default RAM disk size (NEW)
|
||
[*] Initial RAM disk (initrd) support
|
||
|
||
File systems --->
|
||
|
||
<*> Ext3 journalling file system support
|
||
<*> Second extended fs support
|
||
|
||
(important note: do not enable /dev file system support)</PRE
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||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Compile the kernel and install it:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
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||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>make dep bzImage
|
||
make modules modules_install
|
||
cp arch/i386/boot/bzImage /boot/vmlinuz</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> If grub is your bootloader, update /boot/grub/menu.lst
|
||
or /boot/grub/grub.conf:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cat > /boot/grub/menu.lst << EOF
|
||
default 0
|
||
timeout 10
|
||
color green/black light-green/black
|
||
title Linux
|
||
root (hd0,2)
|
||
kernel /boot/vmlinuz ro root=/dev/hda3
|
||
EOF</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Otherwise, update /etc/lilo.conf and run lilo:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cat > /etc/lilo.conf << EOF
|
||
lba32
|
||
boot=/dev/hda
|
||
prompt
|
||
timeout=60
|
||
image=/boot/vmlinuz
|
||
label=Linux
|
||
read-only
|
||
root=/dev/hda3
|
||
EOF
|
||
lilo</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> You may now restart the system.
|
||
</P
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect2"
|
||
><HR><H2
|
||
CLASS="sect2"
|
||
><A
|
||
NAME="install-kernel-2.6"
|
||
></A
|
||
>1.4. Installing Linux-2.6.10</H2
|
||
><P
|
||
> Proceed as described in the previous section, using loop-aes'
|
||
<EM
|
||
>kernel-2.6.10.diff</EM
|
||
> patch instead, and make
|
||
sure cryptoloop support is <EM
|
||
>not</EM
|
||
> activated.
|
||
Note that modules support require that you have the module-init-tools
|
||
package installed.
|
||
</P
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect2"
|
||
><HR><H2
|
||
CLASS="sect2"
|
||
><A
|
||
NAME="install-util-linux"
|
||
></A
|
||
>1.5. Installing util-linux-2.12p</H2
|
||
><P
|
||
> The losetup program, which is part of the util-linux package, must be
|
||
patched and recompiled in order to add strong cryptography support.
|
||
Download, unpack and patch util-linux:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cd /usr/src
|
||
wget http://ftp.kernel.org/pub/linux/utils/util-linux/util-linux-2.12p.tar.bz2
|
||
tar -xvjf util-linux-2.12p.tar.bz2
|
||
cd util-linux-2.12p
|
||
patch -Np1 -i ../loop-AES-v3.0b/util-linux-2.12p.diff</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> To use passwords that are less than 20 characters, enter:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>CFLAGS="-O2 -DLOOP_PASSWORD_MIN_LENGTH=8"; export CFLAGS</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Security is certainly your major concern. For this reason, please do not
|
||
enable passwords shorter than 20 characters. Data privacy is not free,
|
||
one has to 'pay' in form of long passwords.
|
||
</P
|
||
><P
|
||
> Compile losetup and install it as root:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>./configure && make lib mount
|
||
mv -f /sbin/losetup /sbin/losetup~
|
||
rm -f /usr/share/man/man8/losetup.8*
|
||
cd mount
|
||
gzip losetup.8
|
||
cp losetup /sbin
|
||
cp losetup.8.gz /usr/share/man/man8/
|
||
chattr +i /sbin/losetup</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
></DIV
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect1"
|
||
><HR><H1
|
||
CLASS="sect1"
|
||
><A
|
||
NAME="encrypt-root-filesystem"
|
||
></A
|
||
>2. Creating the encrypted root filesystem</H1
|
||
><P
|
||
> Fill the target partition with random data:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>shred -n 1 -v /dev/hda2</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Setup the encrypted loopback device:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>losetup -e aes256 -S xxxxxx /dev/loop0 /dev/hda2</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> To prevent optimized dictionary attacks, it is recommended to add
|
||
the -S xxxxxx option, where "xxxxxx" is your randomly chosen
|
||
seed (for example, you might choose "gPk4lA"). Write down your seed on
|
||
a piece of paper so that you don't loose it afterwards. Also, in order
|
||
to avoid boot-time problems with the keyboard map, do not use non-ASCII
|
||
characters (accents, etc.) in your password. The
|
||
<A
|
||
HREF="http://www.diceware.com/"
|
||
TARGET="_top"
|
||
>Diceware</A
|
||
> site offers
|
||
a simple way to create strong, yet easy to remember, passphrases.
|
||
</P
|
||
><P
|
||
> Now create the ext3 filesystem:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mke2fs -j /dev/loop0</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Check that the password you entered is correct:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>losetup -d /dev/loop0
|
||
losetup -e aes256 -S xxxxxx /dev/loop0 /dev/hda2</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mkdir /mnt/efs
|
||
mount /dev/loop0 /mnt/efs</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> You can compare the encrypted and unencrypted data:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>xxd /dev/hda2 | less
|
||
xxd /dev/loop0 | less</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> It's time to install your encrypted Linux system. If you use a GNU/Linux
|
||
distribution (such as Debian, Slackware, Gentoo, Mandrake, RedHat/Fedora,
|
||
SuSE, etc.), run the following command:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cp -avx / /mnt/efs</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> If you use the Linux From Scratch book, proceed as described in
|
||
the manual, with the modifications below:
|
||
<P
|
||
></P
|
||
><UL
|
||
><LI
|
||
><P
|
||
>Chapter 6 - Installing util-linux:</P
|
||
><P
|
||
>Apply the loop-AES patch after unpacking the sources.</P
|
||
></LI
|
||
><LI
|
||
><P
|
||
>Chapter 8 - Making the LFS system bootable:</P
|
||
><P
|
||
>Refer to the next section (Setting up the boot device).</P
|
||
></LI
|
||
></UL
|
||
>
|
||
</P
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect1"
|
||
><HR><H1
|
||
CLASS="sect1"
|
||
><A
|
||
NAME="setup-boot-device"
|
||
></A
|
||
>3. Setting up the boot device</H1
|
||
><DIV
|
||
CLASS="sect2"
|
||
><H2
|
||
CLASS="sect2"
|
||
><A
|
||
NAME="initial-ramdisk"
|
||
></A
|
||
>3.1. Creating the ramdisk</H2
|
||
><P
|
||
> To begin with, chroot inside the encrypted partition and create
|
||
the boot device mount point:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>chroot /mnt/efs
|
||
mkdir /loader</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Then, create the initial ramdisk (initrd), which will be needed
|
||
afterwards:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cd
|
||
dd if=/dev/zero of=initrd bs=1k count=4096
|
||
mke2fs -F initrd
|
||
mkdir ramdisk
|
||
mount -o loop initrd ramdisk</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> If you're using grsecurity, you may get a "Permission denied" error
|
||
message; in this case you'll have to run the mount command outside chroot.
|
||
</P
|
||
><P
|
||
> Create the filesystem hierarchy and copy the required files in it:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mkdir ramdisk/{bin,dev,lib,mnt,sbin}
|
||
cp /bin/{bash,mount} ramdisk/bin/
|
||
ln -s bash ramdisk/bin/sh
|
||
mknod -m 600 ramdisk/dev/console c 5 1
|
||
mknod -m 600 ramdisk/dev/hda2 b 3 2
|
||
mknod -m 600 ramdisk/dev/loop0 b 7 0
|
||
cp /lib/{ld-linux.so.2,libc.so.6,libdl.so.2} ramdisk/lib/
|
||
cp /lib/{libncurses.so.5,libtermcap.so.2} ramdisk/lib/
|
||
cp /sbin/{losetup,pivot_root} ramdisk/sbin/</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> It's ok if you see a message like "/lib/libncurses.so.5: No such file
|
||
or directory", or "/lib/libtermcap.so.2: No such file or directory";
|
||
bash only requires one of these two libraries. You can check which one
|
||
is actually required with:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>ldd /bin/bash</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Compile the sleep program, which will prevent the password prompt
|
||
being flooded by kernel messages (such as usb devices being registered).
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cat > sleep.c << "EOF"
|
||
#include <unistd.h>
|
||
#include <stdlib.h>
|
||
|
||
int main( int argc, char *argv[] )
|
||
{
|
||
if( argc == 2 )
|
||
sleep( atoi( argv[1] ) );
|
||
|
||
return( 0 );
|
||
}
|
||
EOF
|
||
|
||
gcc -s sleep.c -o ramdisk/bin/sleep
|
||
rm sleep.c</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Create the init script:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cat > ramdisk/sbin/init << "EOF"
|
||
#!/bin/sh
|
||
|
||
/bin/sleep 3
|
||
|
||
echo -n "Enter seed value: "
|
||
read SEED
|
||
|
||
/sbin/losetup -e aes256 -S $SEED /dev/loop0 /dev/hda2
|
||
/bin/mount -r -n -t ext3 /dev/loop0 /mnt
|
||
|
||
while [ $? -ne 0 ]
|
||
do
|
||
/sbin/losetup -d /dev/loop0
|
||
/sbin/losetup -e aes256 -S $SEED /dev/loop0 /dev/hda2
|
||
/bin/mount -r -n -t ext3 /dev/loop0 /mnt
|
||
done
|
||
|
||
cd /mnt
|
||
/sbin/pivot_root . loader
|
||
exec /usr/sbin/chroot . /sbin/init
|
||
EOF
|
||
|
||
chmod 755 ramdisk/sbin/init</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Umount the loopback device and compress the initrd:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>umount -d ramdisk
|
||
rmdir ramdisk
|
||
gzip initrd
|
||
mv initrd.gz /boot/</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect2"
|
||
><HR><H2
|
||
CLASS="sect2"
|
||
><A
|
||
NAME="bootable-cd"
|
||
></A
|
||
>3.2. Booting from a CD-ROM</H2
|
||
><P
|
||
> I strongly advise you to start your system with a read-only
|
||
media, such as a bootable CD-ROM.
|
||
</P
|
||
><P
|
||
> Download and unpack syslinux:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>wget http://ftp.kernel.org/pub/linux/utils/boot/syslinux/syslinux-3.07.tar.bz2
|
||
tar -xvjf syslinux-3.07.tar.bz2</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Configure isolinux:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mkdir bootcd
|
||
cp /boot/{vmlinuz,initrd.gz} syslinux-3.07/isolinux.bin bootcd
|
||
echo "DEFAULT /vmlinuz initrd=initrd.gz ro root=/dev/ram0" \
|
||
> bootcd/isolinux.cfg</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Create and burn the bootable cd-rom iso image:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mkisofs -o bootcd.iso -b isolinux.bin -c boot.cat \
|
||
-no-emul-boot -boot-load-size 4 -boot-info-table \
|
||
-J -hide-rr-moved -R bootcd/
|
||
|
||
cdrecord -dev 0,0,0 -speed 4 -v bootcd.iso
|
||
|
||
rm -rf bootcd{,.iso}</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect2"
|
||
><HR><H2
|
||
CLASS="sect2"
|
||
><A
|
||
NAME="boot-partition"
|
||
></A
|
||
>3.3. Booting from a HD partition</H2
|
||
><P
|
||
> The boot partition can come in handy if you happen to lose your bootable
|
||
CD. <EM
|
||
>Remember that hda1 is a writable media and is thus insecure;
|
||
use it only in case of emergency!</EM
|
||
>
|
||
</P
|
||
><P
|
||
> Create and mount the ext2 filesystem:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>dd if=/dev/zero of=/dev/hda1 bs=8192
|
||
mke2fs /dev/hda1
|
||
mount /dev/hda1 /loader</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Copy the kernel and the initial ramdisk:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cp /boot/{vmlinuz,initrd.gz} /loader</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> If you use grub:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mkdir /loader/boot
|
||
cp -av /boot/grub /loader/boot/
|
||
cat > /loader/boot/grub/menu.lst << EOF
|
||
default 0
|
||
timeout 10
|
||
color green/black light-green/black
|
||
title Linux
|
||
root (hd0,0)
|
||
kernel /vmlinuz ro root=/dev/ram0
|
||
initrd /initrd.gz
|
||
EOF
|
||
grub-install --root-directory=/loader /dev/hda
|
||
umount /loader</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> If you use lilo:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>mkdir /loader/{boot,dev,etc}
|
||
cp /boot/boot.b /loader/boot/
|
||
mknod -m 600 /loader/dev/hda b 3 0
|
||
mknod -m 600 /loader/dev/hda1 b 3 1
|
||
mknod -m 600 /loader/dev/hda2 b 3 2
|
||
mknod -m 600 /loader/dev/hda3 b 3 3
|
||
mknod -m 600 /loader/dev/hda4 b 3 4
|
||
mknod -m 600 /loader/dev/ram0 b 1 0
|
||
cat > /loader/etc/lilo.conf << EOF
|
||
lba32
|
||
boot=/dev/hda
|
||
prompt
|
||
timeout=60
|
||
image=/vmlinuz
|
||
label=Linux
|
||
initrd=/initrd.gz
|
||
read-only
|
||
root=/dev/ram0
|
||
EOF
|
||
lilo -r /loader
|
||
umount /loader</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
></DIV
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect1"
|
||
><HR><H1
|
||
CLASS="sect1"
|
||
><A
|
||
NAME="final-steps"
|
||
></A
|
||
>4. Final steps</H1
|
||
><P
|
||
> Still inside chroot, modify /etc/fstab so that it contains:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>/dev/loop0 / ext3 defaults 0 1</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Delete /etc/mtab and exit from chroot. Finally, run "umount -d /mnt/efs"
|
||
and reboot. If something goes wrong, you can still boot your unencrypted
|
||
partition by entering "Linux root=/dev/hda3" at the LILO: prompt.
|
||
</P
|
||
><P
|
||
> If everything went well, you can now re-partition your disk and encrypt
|
||
hda3 as well as hda4. In the following scripts, we assume that hda3 will
|
||
hold the swap device and hda4 will contain /home; you should initialize
|
||
both partitions first:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>shred -n 1 -v /dev/hda3
|
||
shred -n 1 -v /dev/hda4
|
||
losetup -e aes256 -S xxxxxx /dev/loop1 /dev/hda3
|
||
losetup -e aes256 -S xxxxxx /dev/loop2 /dev/hda4
|
||
mkswap /dev/loop1
|
||
mke2fs -j /dev/loop2</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
><P
|
||
> Then create a script in the system startup directory and update fstab:
|
||
</P
|
||
><P
|
||
> <TABLE
|
||
BORDER="0"
|
||
BGCOLOR="#E0E0E0"
|
||
WIDTH="100%"
|
||
><TR
|
||
><TD
|
||
><FONT
|
||
COLOR="#000000"
|
||
><PRE
|
||
CLASS="screen"
|
||
>cat > /etc/init.d/loop << "EOF"
|
||
#!/bin/sh
|
||
|
||
if [ "`/usr/bin/md5sum /dev/hda1`" != \
|
||
"5671cebdb3bed87c3b3c345f0101d016 /dev/hda1" ]
|
||
then
|
||
echo -n "WARNING! hda1 integrity verification FAILED - press enter."
|
||
read
|
||
fi
|
||
|
||
echo "1st password chosen above" | \
|
||
/sbin/losetup -p 0 -e aes256 -S xxxxxx /dev/loop1 /dev/hda3
|
||
|
||
echo "2nd password chosen above" | \
|
||
/sbin/losetup -p 0 -e aes256 -S xxxxxx /dev/loop2 /dev/hda4
|
||
|
||
/sbin/swapon /dev/loop1
|
||
|
||
for i in `seq 0 63`
|
||
do
|
||
echo -n -e "\33[10;10]\33[11;10]" > /dev/tty$i
|
||
done
|
||
|
||
EOF
|
||
|
||
chmod 700 /etc/init.d/loop
|
||
ln -s ../init.d/loop /etc/rcS.d/S00loop
|
||
vi /etc/fstab
|
||
...
|
||
/dev/loop2 /home ext3 defaults 0 2</PRE
|
||
></FONT
|
||
></TD
|
||
></TR
|
||
></TABLE
|
||
>
|
||
</P
|
||
></DIV
|
||
><DIV
|
||
CLASS="sect1"
|
||
><HR><H1
|
||
CLASS="sect1"
|
||
><A
|
||
NAME="about"
|
||
></A
|
||
>5. About this HOWTO</H1
|
||
><P
|
||
> The Encrypted Root Filesystem HOWTO was first written in november 2002 for the
|
||
<A
|
||
HREF="http://www.linuxfromscratch.org/lfs/news.html"
|
||
TARGET="_top"
|
||
>Linux From Scratch</A
|
||
>
|
||
project. I'd like to thank the many people who have since contributed to
|
||
this document (in reverse chronological order): Micha Borrmann,
|
||
Dennis Lemckert, Oleg Vyushin, Ellen Bokhorst, Daczi L<>szl<7A>, Gaetano Zappulla,
|
||
Guillaume Lehmann, Claude Thomassin, Jean-Philippe Gu<47>rard, Luc Vo Van,
|
||
Jacobus Brink, Ernesto P<>rez Est<73>vez, Matthew Ploessel, Mike Lorek,
|
||
Lars Bungum, Michael Shields, Julien Perrot, Grant Stephenson, Cary W. Gilmer,
|
||
James Howells, Pedro Baez, Josh Purinton, Jari Ruusu and Zibeli Aton.
|
||
</P
|
||
><P
|
||
> This HOWTO has been translated in various languages:
|
||
<P
|
||
></P
|
||
><UL
|
||
><LI
|
||
><P
|
||
><A
|
||
HREF="http://www.traduc.org/docs/HOWTO/lecture/Encrypted-Root-Filesystem-HOWTO.html"
|
||
TARGET="_top"
|
||
>French</A
|
||
></P
|
||
></LI
|
||
><LI
|
||
><P
|
||
><A
|
||
HREF="http://www.linux.it/~gaetano/erfs/"
|
||
TARGET="_top"
|
||
>Italian</A
|
||
></P
|
||
></LI
|
||
><LI
|
||
><P
|
||
><A
|
||
HREF="http://tldp.fsf.hu/HOWTO/Encrypted-Root-Filesystem-HOWTO-hu/"
|
||
TARGET="_top"
|
||
>Hungarian</A
|
||
></P
|
||
></LI
|
||
><LI
|
||
><P
|
||
><A
|
||
HREF="http://doc.nl.linux.org/HOWTO/Encrypted-Root-Filesystem-HOWTO-NL/article.html"
|
||
TARGET="_top"
|
||
>Dutch</A
|
||
></P
|
||
></LI
|
||
></UL
|
||
>
|
||
</P
|
||
><P
|
||
> Please send any comment to
|
||
<A
|
||
HREF="http://www.cr0.net:8040/about/"
|
||
TARGET="_top"
|
||
>Christophe Devine</A
|
||
>.
|
||
</P
|
||
></DIV
|
||
></DIV
|
||
></BODY
|
||
></HTML
|
||
> |