By James M. Garvin

Editor’s note: As part of a recent IT
Soapbox blog post I asked Linux users and
evangelists in the TechRepublic community to step up to the plate and take a
crack at producing some informative articles and downloads on the Linux
operating system. This document is just one of the submissions inspired by that
challenge. Just click the Linux challenge tag to track other published submissions
stemming from this grass roots project.

I am assuming you are
using a Redhat or Redhat-like distribution. Some of these packages can be grabbed
via yum. However, I’m going to have you install them via RPM as you cannot get
all of them via yum. If you are not, you will need to get the proper packages.
For Debian you can use aptget or search for the .deb. For SuSe you can use Yast
or find the distro specific RPMs.

1) Install the DKMS package

rpm –install dkms-1.12-2.noarch.rpm

http://prdownloads.sourceforge.net/poptop/dkms-1.12-2.noarch.rpm

This is dynamic kernel
module support. You need this to simplify setup and configuration at the kernel
level. This will make almost everything transparent to the user during setup.

2) Install the ppp kernel module

rpm –install kernel_ppp_mppe-0.0.4-2dkms.noarch.rpm

http://prdownloads.sourceforge.net/poptop/kernel_ppp_mppe-0.0.4-2dkms.noarch.rpm

Point to Point Protocol
to setup your “modem” or whatever your connection consists of. This
is the portion for your kernel.

3) Make sure ppp is working

modprobe ppp-compress-18 && echo James Garvin has saved me from a life of Windows

Ok, so that is a bit of
fun, but what does that command mean? Well, if on success of the modprobe command, I execute the echo command. Modprobe adds the module to the Linux kernel, while echo simply
writes what ever you say back to the terminal.

4) Upgrade ppp

rpm –upgrade ppp-2.4.3-0.cvs_20040527.4.fc2.i386.rpm

http://prdownloads.sourceforge.net/poptop/ppp-2.4.3-0.cvs_20040527.4.fc2.i386.rpm

This is the ppp for the user. The kernel module for ppp
has been installed and this is for the user.

5) Get the PPTP client

rpm –install pptp-linux-1.5.0-1.i386.rpm

http://prdownloads.sourceforge.net/pptpclient/pptp-linux-1.5.0-1.i386.rpm

This is the “VPN
Client,” so to speak. This is the GUI client in which
you can setup VPN connections and various options.

6) Get phppcntl

rpm –install Getphp-pcntl php-pcntl-4.3.8-1.i386.rpm

http://prdownloads.sourceforge.net/pptpclient/php-pcntl-4.3.8-1.i386.rpm

This is to help the GUI
work.

7) Get the phpgtkmodule

rpm –install php-gtk-pcntl-1.0.0-2.i386.rpm

http://prdownloads.sourceforge.net/pptpclient/php-gtk-pcntl-1.0.0-2.i386.rpm

This file also helps
make the GUI work.

8) Get pptpconfig installed

rpm –install pptpconfig-20040722-0.noarch.rpm

http://prdownloads.sourceforge.net/pptpclient/pptpconfig-20040722-0.noarch.rpm

This command installs
the Point to Point Tunneling Protocol. This is so the VPN can actually create
the tunnel from A to B. VPNs can use two protocols,
L2TP and PPTP. L2TP is Layer 2 Tunneling Protocol and does just what it says.
It works at Layer 2 in the OSI model, the Data Link Layer.

9) Now at the command line type

pptpconfig

This command
will
popup a spiffy GUI for you to use.

Figure A
The spiffy pptconfig GUI

10) Configure your connection

In the Server Tab we
need to configure some basics:

  • Name: The name of the connection. You can call it anything you want
  • Server: The server you are connecting to, either the IP or name of the
    server. eg: 64.233.187.99 or google.com
  • Domain: A domain, if any, that the VPN is connecting to
  • Username: Your login username for the VPN or the intranet
  • Password: The login password for the VPN or the intranet

In the Routing Tab we
need to make sure it is setup properly. Typically we need to send All to Tunnel.However, this can and will vary from VPN to VPN. Check with you
local administrator on what radio button you need to choose.

The DNS Tab is usually
quite simple; it will be either automatic, or we will have to
enter some basic DNS information and any optionswe may need to include.

The Encryption Tab is a
sticky point. We have a number of choices:

  • Require
    Microsoft PointtoPoint Encryption
  • Refuse
    40bit Encryption
  • Refuse
    128bit Encryption
  • Refuse
    Stateless Encryption
  • Refuse
    to Authenticate with EAP

You need to talk to your
administrator and understand what your VPN requires. A typical setup will check
box Require Microsoft PointtoPoint Encryption (for MS
VPNS), Refuse 40bit Encryption, and Refuse Stateless Encryption. However, talk
to your administrator to be sure.

The Miscellaneous Tab is
our final tab. We shouldn’t have anything to do here. The default setup should work
just fine in many cases.

We now click the Addbutton and highlight our
new connection and choose Start.
We have now created a VPN connection to a remote host! Congratulations for
using Linux and sticking with a slightly frustrating task.

If you have any questions or comments please drop me a line
at jmgarvin@itttech.edu.