Install pptpd
aptitude install pptpd
edit /etc/pptpd.conf, and set localip and remoteip (at the bottom)
localip 10.108.98.1 remoteip 10.108.98.2-254
Add the VPN users to /etc/ppp/chap-secrets
# Secrets for authentication using CHAP # client server secret IP addresses user1 pptpd password *
Enable IP forwarding in /etc/sysctl.conf
net.ipv4.ip_forward=1
Make that setting live
sysctl -p
Configure iptables masquerading
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
And, if iptables is blocking traffic, the following rules will open up pptpd
iptables -A INPUT -p tcp -m tcp --dport 1723 -j ACCEPT iptables -A INPUT -p gre -j ACCEPT iptables -A FORWARD -j ACCEPT