Ubuntu-PPTP-VPN-Server

Disclamer: usage of PPTP is discouraged in favor of IPSec. If you can use IPSec, please, just forget about PPTP. Rationales: »http://poptop.sourceforge.net/dox/protocol-security.phtml

That said, you'll perhaps face the need, one of these days, to quickly setup a VPN gateway for your Windows & Linux friends. Let's say you're using this setup:

VPN roadwarriors clients  ------Internet-----[firewall]--------,
   (windows & linux)                                           |
                                                               | your internal LAN
                                                               |  (138.15.0.0/24)
                                                               |
                                                        »vpn server
                                                           138.15.0.10/32

You want your roadwarrios to be considered "like on the LAN" once connected, to browse (CIFS/SMB) and broadcast. They can connect from anywhere in the Internet.

Say your LAN is:

• network 138.15.0.0/24
• gateway (internal iface of your Interet firewall) 138.15.0.254
• internal dns : 138.15.0.1 & 138.15.0.2
• internal wins (you're using windows, isn't it?) : 138.15.0.3

Say you want to affect to the "VPN users" addresses from 138.15.0.50 to 138.15.0.100.

On a fresh new Ubuntu 8.04 server located in your LAN (138.15.0.10), just apt-get install pptpd and then configure the following files:

# etc/pptpd.conf
options /etc/ppp/pptpd.options
logwtmp
localip 138.15.0.10
remoteip 138.15.0.50-100

 /etc/ppp/pptpd.options
name coolvpn
refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128
ms-dns 138.15.0.1
ms-dns 138.15.0.2
ms-wins 139.15.0.3
proxyarp
nodefaultroute
lock
nobsdcomp
auth

 /etc/chap-secrets
user1   coolvpn   user1passwd  "*"
user2   coolvpn   user2passwd  "*"

Then restart pptpd (/etc/init.d/pptpd restart) and don't forget to activate IP forwarding on your ubuntu box (see /etc/sysctl.conf).

Finally, have a redirect rule on your Internet firewall to redirect incoming Internet traffic from any to port 1723 (pptp) to your 139.15.0.10 ubuntubox.

Let's rock then : you've setup a quick & dirty VPN gateway. Just configure your Windows client with the embeded PPTP client ("new connection VPN ...") and your Ubuntu desktops using apt-get install network-manager-pptp. Have a cup of coffee to the next WIFI pub, and test.

Once again: it'll work like a charm, but don't forget the disclamer...