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PPTP Client


Knoppix HOWTO

by James Cameron
31st May 2006

These are instructions for installing PPTP Client on Knoppix. The instructions were tested against the Knoppix 4.0.2 DVD.


Installing MPPE Support

If you are trying to connect to a Microsoft Windows VPN Server, and it is set to require encryption, then you will need MPPE support in the kernel. If you know you don't, then skip this step.

If the kernel version of your Knoppix is 2.6.15 or later, you already have MPPE support and you can skip this step.

Bob McLaren wrote to us to say that our Debian MPPE DKMS HOWTO should be used on Knoppix, with a few precautions:

  • do not attempt to load the kernel-source, because it's already there,

  • when using apt-get to install kernel-ppp-mppe and dkms, do not install gcc, because the new version of gcc causes module incompatibility errors which show up in dmesg,

  • after the dkms add step, copy /var/lib/dkms/kernel_ppp_mppe/1.0.2/source/ppp-comp.h over to /usr/include/linux/ppp-comp.h otherwise the build will fail because several definitions are missing.

After following the Debian MPPE DKMS HOWTO with the additional notes above, return here.


Installing the Configuration Program

Note: you may wish to skip the configuration program and configure the client by hand.

  1. add the following lines to the sources list file, /etc/apt/sources.list :

    # James Cameron's PPTP GUI packaging
    deb http://quozl.netrek.org/pptp/pptpconfig ./

    Note: can use a text editor, or simply cat the lines on to the end of the file using >>, but if you make a mistake in formatting you will likely be told by the apt-get update step.

  2. update the list of packages:

    apt-get update

  3. install the PPTP Client GUI:

    apt-get install pptpconfig


Configuration

  1. obtain from your PPTP Server administrator:

    • the IP address or host name of the server,
    • the authentication domain name, (e.g. WORKGROUP),
    • the username you are to use,
    • the password you are to use,
    • whether encryption is required.

  2. run pptpconfig as root, and a window should appear,

  3. enter the server, domain, username and password into the Server tab,

  4. if you decided in Installation step 1 above that you would need MPPE, and if your administrator says encryption is required, then on the Encryption tab, click on Require Microsoft Point-to-Point Encryption (MPPE),

  5. click on Add, and the tunnel will appear in the list,

  6. click on the tunnel to select it, click on Start, and a window will appear with the tunnel connection log and status,

  7. if the connection fails, you will need to gather more information, so on the Miscellaneous tab, click on Enable connection debugging facilities, click Update, try Start again, then look at the Diagnosis HOWTO for whatever error is displayed.

  8. if the connection succeeded, you can try the Ping test button. If the ping fails, you should try to find out why before proceeding. If the ping works, then the tunnel is active and you may now work on routing.

  9. decide whether all your network traffic should go via the tunnel or not. If so, Stop the tunnel, select it again, then on the Routing tab, click on All to Tunnel, then click Update and try Start again. Now try to access the network behind the server.

  10. on the other hand, if only some of your network traffic should go via the tunnel, you will need to obtain from the server administrator or folk lore a series of network routes to enter. Stop the tunnel, select it again, then click on either Client to LAN or LAN to LAN on the Routing tab, use the Edit Network Routes button to enter the routes one by one, and then try Start again. Now try to access the network behind the server.

    For further help with Routing, read our Routing HOWTO.


Diagnosing Problems

If you have problems with the tunnel and need to ask for help, start pppd with complete logging:

# script pptp.log
Script started, file is pptp.log
# pppd call tunnelname dump debug logfd 2 nodetach
# exit
Script done, file is pptp.log

where tunnelname is the name of the tunnel you created in the configuration program. For more detail, see enabling debug logging.

This will give you a file pptp.log that you can use to search for known solutions in the Diagnosis HOWTO or attach to an e-mail to the mailing list.


Configuration, by hand

  1. obtain from your PPTP Server administrator:

    • the IP address or host name of the server ($SERVER),
    • the name you wish to use to refer to the tunnel ($TUNNEL),
    • the authentication domain name ($DOMAIN),
    • the username you are to use ($USERNAME),
    • the password you are to use ($PASSWORD),
    • whether encryption is required.

    In the steps below, substitute these values manually. For example, where we write $PASSWORD we expect you to replace this with your password.

  2. create or edit the /etc/ppp/options.pptp file, which sets options common to all tunnels:

    lock noauth nobsdcomp nodeflate

  3. create or add lines to the /etc/ppp/chap-secrets file, which holds usernames and passwords:

    $DOMAIN\\$USERNAME PPTP $PASSWORD *

    Note: if you are using a PPTP Server that does not require an authentication domain name, omit the slashes as well as the domain name.

    Note: if the passwords contain any special characters, quote them. See man pppd for more details.

  4. create a /etc/ppp/peers/$TUNNEL file:

    pty "pptp $SERVER --nolaunchpppd"
    name $DOMAIN\\$USERNAME
    remotename PPTP
    require-mppe-128
    file /etc/ppp/options.pptp
    ipparam $TUNNEL

    Note: if you do not need MPPE support, then remove the require-mppe-128 option from this file and /etc/ppp/options.pptp.

  5. start the tunnel using the pon command:

    pon $TUNNEL

    to further diagnose a failure, add options to the command:

    pon $TUNNEL debug dump logfd 2 nodetach

    Note: we have further information on enabling debug mode, and on diagnosing problems.

  6. stop the tunnel using the poff command:

    poff $TUNNEL

  7. to script the tunnel connection so that something is done as soon as the tunnel is up, use either ip-up.d scripts or the updetach keyword.

    1. see the Routing HOWTO for examples of ip-up.d scripting that adds routes or iptables rules.

    2. using updetach will cause pppd to fork, detach, and exit with success once the network link is up. This example connects a provider link, then the tunnel, then runs fetchmail to get new e-mail:

      pon provider updetach && pon $TUNNEL updetach && fetchmail

      Note: the double ampersand && means that the commands following it will only be executed if the command to the left of it was successful. If the tunnel fails to connect, the fetchmail will not happen.

  8. to have the tunnel automatically restarted if it fails, add the option persist to either the command line or the /etc/ppp/peers/$TUNNEL file.

  9. to have the tunnel started on system boot:

    • for Debian Sarge and later, edit the /etc/network/interfaces file, and add this section:

      auto tunnel
      iface tunnel inet ppp
              provider $TUNNEL

    • for Debian Woody, edit the /etc/ppp/no_ppp_on_boot file, remove the first line comment, and change the word provider to the name of your tunnel, so that it looks like this:

      #!/bin/sh
      ...
      $PPPD call $TUNNEL

      (The line ... means the other lines in the file, it doesn't mean a line with three dots.)

      Then rename the no_ppp_on_boot file and make it executable:

      # mv /etc/ppp/no_ppp_on_boot /etc/ppp/ppp_on_boot
      # chmod +x /etc/ppp/ppp_on_boot

    Every time your computer starts, the tunnel will be started automatically.

  10. to set up routing, read our Routing HOWTO.


Comments

If you have comments on this document, please send them to the author at quozl at laptop.org. But if you need help, use the mailing list so that we can share the load.

ChangeLog

DateChange
2006-05-31 Admit which version of Knoppix this relates to.
2006-05-29 Derive from Debian HOWTO.