How to Configure VPN (PPTP) Server on CentOS

In this document you will find the steps on how to build a Linux Point to Point Tunneling Protocol (PPTP) server using Poptop.

This allows roaming users to connect to their corporate network from anywhere on the Internet securely and inexpensively.

It supports Windows 95/98/Me/NT/2000/XP PPTP clients and Linux PPTP clients.

Requirements: -

Server: CentOS 5.3

kernel-2.6.18-128.el5

ppp-2.4.4-2.el5

pptpd-1.3.4-1.rhel5

Kernel version 2.6.15 or above has MPPE built-in which is required for MSCHAPv2. CentOS 5 kernel version is 2.6.18 that means you do not need to install the MPPE module. CentOS 5comes with ppp-2.4.4-1.el5 and it is MPPE support enabled.

Step-1: Install ppp if already not installed and Check if kernel supports MPPE

#yum install ppp

Run the command below to test if your kernel supports MPPE and you should get a return an “ok”: -

#modprobe ppp-compress-18 && echo ok

Step-2: Install PPTPD

You cannot install the pptpd using yum utility because it’s not in yum repo. Download the RPM file pptpd-1.3.4-1.rhel5.1.i386.rpm from http://poptop.sourceforge.net/yum/stable/packages/

#wget http://poptop.sourceforge.net/yum/stable/packages/pptpd-1.3.4-2.rhel5.x86_64.rpm

Install the RPM by running this command: -

#rpm -ivh pptpd-1.3.4-2.rhel5.x86_64.rpm

Step-3: Configuration

Change the /etc/ppp/options.pptpd as below: -

#vi /etc/ppp/options.pptpd

name pptpd

refuse-pap

refuse-chap

refuse-mschap

require-mschap-v2

require-mppe-128

proxyarp

lock

nobsdcomp

novj

novjccomp

nologfd

Change the following file /etc/pptpd.conf

#vi /etc/pptpd.conf

option /etc/ppp/options.pptpd

logwtmp

localip 192.168.2.1

remoteip 192.168.2.11-15

Add the following username (johndie) and password (passwrd) in /etc/ppp/chap-secrets as below: -

# Secrets for authentication using CHAP

# client server secret IP addresses

shamsul pptpd passwrd *

Step-4: Run the following command to enable the pptpd to start automatically in runlevel 3 and 5 as below: -

#chkconfig --level 35 pptpd on

Now, you can start the pptpd service as below: -

#service pptpd start

Step-5: For pptpd to work, the packet forwarding must be enabled. Edit /etc/sysctl.conf and change the line to below: -

#vi /etc/sysctl.conf

net.ipv4.ip_forward = 1

To enable it immediately, run following command: -

#sysctl -p

Now test your setup by creating a vpn connection from any windows or linux pc.

credit to: http://almamunbd.blogspot.com/2009/06/how-to-configure-vpn-pptp-server-on.html

Setup VNC Server on CentOS

1. yum install vncserver 
2. vi /etc/sysconfig/vncservers
VNCSERVERS="1:tiger 2:albatros 3:leopard"                                      VNCSERVERARGS[1]="-geometry 1024x768 -depth 16"                                      VNCSERVERARGS[2]="-geometry 800x600 -depth 8"                                      VNCSERVERARGS[3]="-geometry 1024x768 -depth 16"

    3.  vncpasswd tiger

    4.  vi /home/tiger/.vnc/xstartup (uncomment below line)

         unset SESSION_MANAGER

         exec /etc/X11/xinit/xinitrc

    5. /etc/init.d/vncserver start