How to configure a Linux PPTP VPN client

Configuring a VPN client connection is a simple matter of point and click in Windows OSes, but in Linux it is involves installing a package, configuring passwords, VPN server settings and finally routing the traffic destined for the VPN network via the VPN connection. The package named pptp is used on the client side for configuring a connection. To setup a VPN server read How to setup a VPN Server in Windows Server 2008. This tutorial is for both Debian Linux variants and Red Hat Linux variants.

Fedora/Red Hat/CentOS PPTP Client Installation

Install the pptp client

yum install pptp

Debian/Ubuntu PPTP Client Installation

Use the apt-get command

apt-get install pptp-linux

Configuring VPN credentials and server settings

Edit the following file and enter your VPN username and password

vi /etc/ppp/chap-secrets

The syntax of the file is as follows

DOMAIN\\username      PPTP      vpnpassword     *

For example to configure a user named jesin on example.com with pass1 as the password enter

EXAMPLE\\jesin        PPTP      pass1           *

If your VPN network doesn’t come under a domain replace DOMAIN with your VPNSERVER name.

Next is to configure the VPN server settings. Create and edit a new file under the peers directory

vi /etc/ppp/peers/vpnconnection1

Add content according to the syntax below

pty "pptp vpn-server-hostname-or-ip-address --nolaunchpppd"
name DOMAIN\\username
remotename PPTP
require-mppe-128
file /etc/ppp/options.pptp
ipparam vpnconnection1

Here “DOMAIN\\username” is the same as the one entered in the chap-secrets file. The ipparam should contain the name of the newly created file, in this case it is “vpnconnection1”

Adding a route to the routing table

All traffic for the VPN network should pass through the VPN interface so an entry has to be added to the routing table. To automatically add an entry whenever a VPN connection is established create and edit the following file

vi /etc/ppp/ip-up.d/vpn1-route

Add the following content

#!/bin/bash
route add -net 10.0.0.0/8 dev ppp0

Make the file executable

chmod +x /etc/ppp/ip-up.d/vpn1-route

Testing the connection

To connect using the newly created VPN connection use the following command

pppd call vpnconnection1

Take a peek into the messages log file using the following command

tail -f /var/log/messages

you should see something similar to this

Nov 27 13:46:20 server1 kernel: [ 800.071028] PPP generic driver version 2.4.2
Nov 27 13:46:20 server1 pppd[1083]: pppd 2.4.5 started by root, uid 0
Nov 27 13:46:20 server1 pppd[1083]: Using interface ppp0
Nov 27 13:46:20 server1 pppd[1083]: Connect: ppp0 /dev/pts/0
Nov 27 13:46:25 server1 pppd[1083]: CHAP authentication succeeded
Nov 27 13:46:25 server1 kernel: [ 804.683790] padlock: VIA PadLock Hash Engine not detected.
Nov 27 13:46:25 server1 kernel: [ 804.687408] PPP MPPE Compression module registered
Nov 27 13:46:25 server1 pppd[1083]: MPPE 128-bit stateless compression enabled
Nov 27 13:46:26 server1 pppd[1083]: local IP address 10.0.0.11
Nov 27 13:46:26 server1 pppd[1083]: remote IP address 10.0.0.12

Try pinging a system in the VPN network and you should get proper replies.

Disconnecting the connection

To disconnect the PPTP VPN connection use the killall command

killall pppd