Setting up a PPTP VPN server on a Linux machine is a straightforward process. This guide will walk you through the steps required to get your VPN server up and running.

Step 1: Install PPTPD

PPTP depends on the PPP and PPTPD packages. To install them, run the following commands:

yum install pptpd

Or, download and install the PPTPD package using:

wget http://poptop.sourceforge.net/yum/stable/packages/pptpd-1.4.0-1.el6.x86_64.rpm
rpm -Uhv pptpd-1.4.0-1.el6.x86_64.rpm

Step 2: Configure PPTPD

After installation, you’ll need to configure the PPTPD server. Start by editing the IP settings in the /etc/pptpd.conf file:

nano /etc/pptpd.conf

Add or modify the following lines:

localip 192.168.0.1    # Server's primary IP
remoteip 192.168.0.100-200

Next, update the DNS settings in the /etc/ppp/options.pptpd file:

nano /etc/ppp/options.pptpd

Add the following lines:

ms-dns 8.8.8.8
ms-dns 8.8.4.4

Step 3: Create a VPN User

To allow access to the VPN server, you’ll need to create a user account. Add the user credentials in the /etc/ppp/chap-secrets file:

nano /etc/ppp/chap-secrets

Insert the following line:

username pptpd password *

Replace username and password with your desired credentials.

Step 4: Enable IP/Network Forwarding

IP forwarding is essential for routing packets between VPN clients and the internet. Enable IP forwarding by editing the /etc/sysctl.conf file:

nano /etc/sysctl.conf

Uncomment or add the following line:

net.ipv4.ip_forward = 1

To apply the changes, run:

sysctl -p

Step 5: Configure IPTables for NAT

NAT (Network Address Translation) allows VPN clients to access the internet through the server’s public IP. First, identify your network interface (e.g., eth0, ens33) by using the ifconfig command.

Assuming your network interface is eth0, add the following IPTables rules:

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 192.168.0.0/24 -j ACCEPT

Save these rules to ensure they persist after a reboot.

Step 6: Start and Enable the PPTPD Service

Finally, start the PPTPD service and enable it to run at boot:

systemctl start pptpd
systemctl enable pptpd

Your PPTP VPN server is now set up and ready to use. You can connect to it using any PPTP VPN client with the user credentials created earlier.