sudo apt-get install pptpd

sudo vim /etc/ppptpd.conf
localip 192.168.5.1
remoteip 10.100.5.2-254

sudo vim /etc/ppp/pptpd-options
ms-dns 8.8.8.8
ms-dns 8.8.4.4

sudo vim /etc/ppp/chap-secrets
user    pptpd    password    *

sudo vim /etc/sysctl.conf
net.ipv4.ip_forward=1
sudo sysctl -p

sudo iptables -t nat -A POSTROUTING -s 192.168.5.0/24 -o eth0 -j MASQUERADE

sudo iptables-save > /etc/iptables-rules

sudo vim /etc/network/interfaces
pre-up iptables-restore < /etc/iptables-rules