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1 Introduction

1.1 Download document, Messages, Bug Reports etc.

You can download this entire HOWTO here

See the changelog for the latest changes.

1.2 A short Introduction to PPP and RAS

PPP ('Point to Point Protocol') is a protocol , that makes it possible to make IP-Links (Internet Protocol) between two computers with a modem.

The operating system Linux has this protocol in his kernel (If you compiled it into the kernel). For a ppp-link you need to start a daemon called pppd.

With PPP you can make a link between two hosts which understand the protocol. A link between a Linux host, acting as client and a Windows NT server, acting as server, is called a (Microsoft term) ' Remote Access Service' (RAS) link.

1.3 Links to related information

2 General and Patching PPPD

2.1 General

For a RAS link you need on the Windows NT server :
  • An user login, authorized for RAS
  • A Windows NT server with RAS activated :
  • 'Callback Feature'
    • This document tells you how do configure a PPP-link using MS-CHAP. If you use another protocol you can find this in the original PPP/NT Howto or in the PPP Howto. PAP, CHAP and Clear Text authentication are implemented without modification by Microsoft. For more information about your NT-Server you need to contact your NT administrator.

    2.2 What do you need ?

    For a working pppd daemon with MS-CHAP and callback you need to patch the pppd-daemon. So you need the ppp-source. You can download this at http://www.van-dijk.net/PPP-NT-HOWTO/download/ppp-2.3.11.tar.gz

    Because MS-CHAP uses DES encryption you need the DES library. If you have glibc2 with libcrypt (this is in for example RedHat 5.2), you have the library, and you don't have to download it. If not, you can download it at : If you don't want to do the patching yourself you can download here tar.gz and RPM packages (DES not included).


    2.3 Patching PPPD for MS-CHAP

    After installing the pppd-source there is a file called README.mschap80 in the source root. This file describes how you can compile MS-CHAP into ppp(d). In the ppp-2.3.(7,11) I downloaded was this patch already. Before you do this you need install DES !! Don't recompile the ppp-source yet. You have to do more patching.

    2.4 Patching PPPD for callback

    In the root of the ppp-source there is another document that describes a patch , README.cbcp. Read this and install this patch.

    3 Configuration(s)

    3.1 System configuration

    The output on the following pages is based on this configuration :

    Configuration Linux Machine :
    Configuration NT RAS Server
    (N.B. Several data I made up. My boss don't want you to know the real ones.)

    3.2 Working configuration(s)

    The patched pppd is reported working with the following configurations :



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