http://forums.fedoraforum.org/showthread.php?postid=293965#poststop
 
This howto will show how to create a pptp vpn server for windows and linux clients. This vpn will use mppe encryption (40 or 128 bits), so we'll have to add a new kernel module.

1 - Go to www.poptop.org , download page and get these:

* kernel 2.6.15 and after have ppp_mppe built-in

- dkms-2.0.5-1.noarch.rpm (dinamic kernel module system)
- kernel_ppp_mppe-0.0.5-2dkms.noarch.rpm (kernel module for mppe encryption)
- ppp-2.4.3-5.src.rpm (they dont have the binary for fc4 yet)
- pptpd-1.2.1-1.i386.rpm

2 - Install

- do it in the order above.
- rpm -ivh dkms...
- rpm -ivh kernel_ppp...
- rpm -ivh ppp... (the source !, so lets make the rpm)
--- rpmbuild -ba /usr/src/redhat/SPECS/ppp.spec
--- rpm -Uvh /usr/src/redhat/RPMS/i386/ppp-2.4.3-5.fc4... (update ppp)
- rpm -ivh pptpd-1.2....

3 - Configuration

/etc/pptpd.conf:

options /etc/ppp/options.pptpd
debug
logwtmp
# this is my example conf, put yours:
localip 10.1.0.1 #(your internal vpn server ip)
remoteip 10.1.0.2-10 #(the ip range that will be given for client hosts)


/etc/ppp/options.pptpd:

name pptpd
refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128 #or 40
ms-wins 10.1.0.1
proxyarp
debug
lock
nobsdcomp
novjccomp
novj
nologfd
auth
nologfd
require-mppe
# defaultroute

/etc/ppp/chap-secrets:
# user pptpd password "*"
john pptpd johnpass "*"


4 - Firewall settings

In the firewall, open 1723 tcp port and the GRE protocol
For example, in /etc/sysconfig/iptables

-A RH-Firewall-1-INPUT -p gre -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp -m state --dport 1723 --state NEW -j ACCEPT


5 - Start pptpd

# service pptpd start

6 - Clients configuration

Windows XP:

Start / Connection / Show Connection / Crate a new connection

then create a vpn connection type:
put the vpn server ip,
username and password created before and CONNECT !

Linux client:

use this howto:
http://pptpclient.sourceforge.net/howto-fedora-core-4.phtml