I Enviroments

Ubuntu 14.04 LTS/16.04 LTS

PPTP

iptables

II Prerequisites

1. PPTP

$ sudo apt-get install pptpd

# install pptpd

$ sudo vi /etc/pptpd.conf

# Uncommnet the following contents

# localip 192.168.0.1  

# remoteip 192.168.0.234-238,192.168.0.245  

$ sudo vi /etc/ppp/pptpd-options

# Uncommnet and change the following contents

# ms-dns 8.8.8.8

# ms-dns 114.114.114.114  

$ sudo vi /etc/ppp/chap-secrets

# Insert user and password.

username pptpd userpassword *

$ sudo vi /etc/sysctl.conf

# Uncommnet the following contents

# net.ipv4.ip_forward=1

$ sudo sysctl -p

# Display "net.ipv4.ip_forward = 1".

2. iptables

$ sudo apt-get install iptables

# Install iptables.

$ sudo iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j MASQUERADE

# Insert the forwarding rules.

$ sudo touch /etc/iptables.rules

# Create forwarding rules file.

$ sudo chmod a+w /etc/iptables.rules

# Change the permission.

$ sudo iptables-save > /etc/iptables.rules

# write permissions into file.

$ sudo vi /etc/network/interfaces

# Add the following content into the end of file.

pre-up iptables-restore < /etc/iptables.rules

$ sudo /etc/init.d/pptpd restart

# Restart the service.

$ sudo vi /etc/rc.local

# Add the following content into the end for self-starting.

/etc/init.d/pptpd restart