How to cross-compile vpnc for the Nokia N900

This document provides a step-by-step tutorial for cross-compiling the program vpnc (a client for cisco vpn concentrator) for the Nokia N900 using the Maemo development tool MADDE (version 0.6.14, published 2010-02-05) on a 64-bit linux box running Fedora 12, and instructions are given to get cross-compiled vpnc running on the N900.

Prerequisites

Experience with the linux command-line.
A working installation of MADDE version 0.6.14.
Source code of vpnc version 0.5.3 .
Source code of GNU's basic cryptographic library libgcrypt version 1.4.5

Typographical conventions

Program names, library names, file names and code are set in fixed-width font.
The user prompt of the command line is set as >
The root prompt of the command line is set as #

Summary of workflow

Problem: vpnc depends on libgcrypt which itself depends on libgpg-error. Both libraries are missing in MADDE version 0.6.14 resulting in the following basic workflow:

build these missing libraries libgpg-error and libgcrypt using MADDE version 0.6.14.
patch MADDE to provide libgpg-error and libgcrypt.
build vpnc with the patched MADDE.

1. Patching MADDE for `libgpg-error`

Luckily we don't have to build libgpg-error, because the Maemo fremental repository provides a precompiled debian armel package with the static library and all the headers needed (libgpg-error-dev_1.4-2_armel.deb).



Debian packages are archive files containing the three
files debian-binary, control.tar.gz
and data.tar.gz. The needed archived files reside in
data.tar.gz. 

Basically the only thing we have to do is
  

   download the debian armel package from the Maemo fremental repository.
  
 extract the library and header files from the debian package.
  
 patching MADDE by copying the extracted files the proper
  subdirectory of the MADDE installation.
  
  which is achieved by the following sequence of commands:



a. Extracting files from debian package

  > mkdir ~/TMP
  > cd ~/TMP
  > wget -v http://repository.maemo.org/extras-devel/pool/fremantle/free/libg/libgpg-error/libgpg-error-dev_1.4-2_armel.deb
  > ar p libgpg-error-dev_1.4-2_armel.deb data.tar.gz | tar zxf - ./usr/include/gpg-error.h
  > ar p libgpg-error-dev_1.4-2_armel.deb data.tar.gz | tar zxf - ./usr/lib/libgpg-error.a
  > ar p libgpg-error-dev_1.4-2_armel.deb data.tar.gz | tar zxf - ./usr/lib/libgpg-error.la


b. Patch MADDE
  > cd ~/.madde/0.6.14/sysroots/fremantle-arm-sysroot-2.2009-51-1-qt453/usr/lib
  > cp ~/TMP/usr/lib/libgpg-error.a .
  > cp ~/TMP/usr/lib/libgpg-error.la .
  > cd ../include/
  > cp ~/TMP/usr/include/gpg-error.h .



2. Patching MADDE for libgcrypt

Next download the sources of libgcrypt, cross-compile them
  using the libgpg-error-patched MADDE and finally patch MADDE
  with the freshly build library and headers of libgcrypt.


a. Download and cross-compile libgcrypt

  > cd ~/TMP
  > wget -v ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.4.5.tar.bz2
  > tar jxvf libgcrypt-1.4.5.tar.bz2
  > cd libgcrypt-1.4.5
  > mad ./configure --host=arm
  > mad make



b. Patch MADDE

  > cd ~/.madde/0.6.14/sysroots/fremantle-arm-sysroot-2.2009-51-1-qt453/usr/lib
  > cp ~/TMP/libgcrypt-1.4.5/src/libgcrypt.a .
  > cp ~/TMP/libgcrypt-1.4.5/src/libgcrypt.la .
  > cd ../include
  > cp ~/TMP/libgcrypt-1.4.5/gcrypt.h .
  > cp ~/TMP/libgcrypt-1.4.5/gcrypt-module.h .



3. Build vpnc using the patched MADDE

Finally the stage is set to cross-compile vpnc

  > cd ~/TMP
  > wget -v http://www.unix-ag.uni-kl.de/~massar/vpnc/vpnc-0.5.3.tar.gz
  > tar zxvf vpnc-0.5.3.tar.gz
  > cd vpnc-0.5.3
  > mad make -i
  > mad strip vpnc


(Note: You will encounter a make error after vpnc and
  utilities smoothly compiled and linked. Don't be worried!! The error
  occures during generation of vpnc's man page, which is done
  by the Perl script makeman.pl. The script tries to execute
  the cross-compiled vnpc to get the long version number of
  the program, which must fail for obvious reasons. We can
  not run an ARM executable on an i386 plattform.)

Next we have to transfer the vpnc build to the N900.


4. Copy vpnc and utilities to the N900

Since we have to copy a bunch of files to the N900, we will make a tar
archive

  > mkdir ~/TMP/vpnc-N900
  > cd ~/TMP/vpnc-N900
  > cp ../vpnc-0.5.3/vpnc .
  > cp ../vpnc-0.5.3/vpnc-script .
  > cp ../vpnc-0.5.3/vpnc-disconnect .


Create a vpnc configuration file named default.conf
  (replace all my.dummys in the following example with your vpn
   connection details)

  IPSec gateway my.vpn.gateway
  IPSec ID my.ipsec.id
  IPSec secret my.secret
  Xauth username my.username
  

Create a shell script named vpnc.sh with the following
content

  #!/bin/sh

  case "$1" in
      start)
      shift
      /usr/local/sbin/vpnc $*
      ;;
      stop)
      /usr/local/sbin/vpnc-disconnect
      ;;
      *)
      echo $0 "{start|stop}"
      exit 1
  esac

  # End of file


Finally pack the files into a tar archive (vpnc-N900.tar.gz)
and copy this file to /home/user on your N900.

  > cd ..
  > tar cvf - vpnc-N900 | gzip --best -> vpnc-N900.tar.gz



5. Install vpnc on N900

Copy vpnc-N900.tar.gz to /home/user on your
  N900. Open a xterm and
  unpack vpnc-N900.tar.gz

  > tar zxvf vpnc-N900.tar.gz
  > cd vpnc-N900
  > chmod +x vpnc.sh vpnc vpnc-disconnect vpnc-script
  > cp vpnc.sh ../


If you have not done yet, edit default.conf and fill in
your vpn connection details !!!

  > vi default.conf


The next 2 steps require root access on you N900.

Warning: Root Access enables users to change
the file-system and gives full access to all system files. DON'T PLAY WITH
IT, if you don't know what you are doing. (You can easily break your
N900)

Copy files to system location
  > sudo gainroot
  # cp vpnc vpnc-disconnect /usr/local/sbin
  # mkdir /etc/vpnc
  # cp default.conf vpnc-script /etc/vpnc


Edit the /etc/sudoers file (using the visudo
   utility) to allow the user to run vpnc,
   vpnc-disconnect and /home/user/vpnc.sh as sudo
   without passwd

  # EDITOR=/usr/bin/vi visudo


add the following three lines at the end of
the /etc/sudoers file

  user ALL = NOPASSWD /usr/local/sbin/vpnc
  user ALL = NOPASSWD /usr/local/sbin/vpnc-disconnect
  user ALL = NOPASSWD /home/user/vpnc.sh


Warning: Root Access enables users to change
the file-system and gives full access to all system files. DON'T PLAY WITH
IT, if you don't know what you are doing. (You can easily break your
N900)

Finally leave root shell by pressing Ctrl-D

6. Enjoy your vpn connection

Activate/deactivate the vpn connection in the xterm as follows

  > sudo ./vpnc.sh start
  (enter passwd when propted)

  > sudo ./vpnc.sh stop
  


7. Cleanup files

Remove vpnc-N900.tar.gz and the
  directory vpnc-N900/ to save space.

  > rm vpnc-N900.tar.gz
  > rm -rf vpnc-N900




I hope this document was helpful. In case of questions
  feel free to send email to xtof@tbi.univie.ac.at (Please
  quote N900 in the subject)



Last modified: 2010-03-03 16:33:38 xtof

How to cross-compile vpnc for the Nokia N900

Prerequisites

Typographical conventions

Summary of workflow

1. Patching MADDE for `libgpg-error`

a. Extracting files from debian package

b. Patch MADDE

2. Patching MADDE for `libgcrypt`

a. Download and cross-compile `libgcrypt`

b. Patch MADDE

3. Build `vpnc` using the patched MADDE

4. Copy `vpnc` and utilities to the N900

5. Install `vpnc` on N900

6. Enjoy your vpn connection

7. Cleanup files

How to cross-compile vpnc for the Nokia N900

Prerequisites

Typographical conventions

Summary of workflow

1. Patching MADDE for libgpg-error

a. Extracting files from debian package

b. Patch MADDE

2. Patching MADDE for libgcrypt

a. Download and cross-compile libgcrypt

b. Patch MADDE

3. Build vpnc using the patched MADDE

4. Copy vpnc and utilities to the N900

5. Install vpnc on N900

6. Enjoy your vpn connection

7. Cleanup files

1. Patching MADDE for `libgpg-error`

2. Patching MADDE for `libgcrypt`

a. Download and cross-compile `libgcrypt`

3. Build `vpnc` using the patched MADDE

4. Copy `vpnc` and utilities to the N900

5. Install `vpnc` on N900