PPTP Server

The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. PPTP uses a control channel over TCP and a GRE tunnel operating to encapsulate PPP packets.

This entry will show you on how to create a PPTP server in Arch.

Installation

Install pptpd, available in the Official Repositories.

Configuration

Now, edit the file /etc/pptpd.conf

/etc/pptpd.conf

option /etc/ppp/pptpd-options
localip 172.16.36.1
remoteip 172.16.36.2-254

Now, edit the file /etc/ppp/pptpd-options

/etc/ppp/pptpd-options

name pptpd
refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128
proxyarp
lock
nobsdcomp
novj
novjccomp
nologfd
ms-dns 8.8.8.8
ms-dns 8.8.4.4

Now we must add my users & passwords in /etc/ppp/chap-secrets

/etc/ppp/chap-secrets

<username>     pptpd     <password>   *

Now, enable IP Forwarding (this can be done on multiple places, see Sysctl#Configuration for details about possible configuration files):

/etc/sysctl.d/99-sysctl.conf

net.ipv4.ip_forward=1

Now apply the changes made to any sysctl configuration files:

# sysctl --system

iptables firewall configuration

Configure your iptables settings to enable access for PPTP Clients

iptables -A INPUT -i ppp+ -j ACCEPT
iptables -A OUTPUT -o ppp+ -j ACCEPT

iptables -A INPUT -p tcp --dport 1723 -j ACCEPT
iptables -A INPUT -p 47 -j ACCEPT
iptables -A OUTPUT -p 47 -j ACCEPT

iptables -F FORWARD
iptables -A FORWARD -j ACCEPT

iptables -A POSTROUTING -t nat -o eth0 -j MASQUERADE
iptables -A POSTROUTING -t nat -o ppp+ -j MASQUERADE

Now save the new iptables rules with:

# iptables-save > /etc/iptables/iptables.rules

Read Iptables for more information.

ufw firewall configuration

Configure your ufw settings to enable access for PPTP Clients.

You must change default forward policy in /etc/default/ufw

/etc/default/ufw

DEFAULT_FORWARD_POLICY=”ACCEPT”

Now change /etc/ufw/before.rules, add following code after header and before *filter line

/etc/ufw/before.rules

# nat Table rules
*nat
:POSTROUTING ACCEPT [0:0]

# Allow traffic from clients to eth0
-A POSTROUTING -s 172.16.36.0/24 -o eth0 -j MASQUERADE

# don.t delete the .COMMIT. line or these nat table rules won.t be processed
COMMIT

Open pptp port 1723

ufw allow 1723

Restart ufw for good measure

ufw disable
ufw enable

Start up

Now you can start your PPTP Server by this command:

# systemctl start pptpd.service

If you want to start your PPTP server while system startup, you could enable it in systemd.

# systemctl enable pptpd.service

Troubleshooting

• If you keep getting error 619 on the client side, search for the logwtmp option in /etc/pptpd.conf and comment it out. When this is enabled, wtmp will be used to record client connections and disconnections.

#logwtmp

• If you keep getting pptpd[xxxxx]: Long config file line ignored when checking status by "systemctl status pptpd", you need to add a blank line at the end of /etc/pptpd.conf.[1]

• If you keep getting ppp0: ppp: compressor dropped pkt when client connected into server, you need add the script following into /etc/ppp/ip-up.d/mppefixmtu.sh

#!/bin/sh
CURRENT_MTU="`ip link show $1 | grep -Po '(?<=mtu )([0-9]+)'`"
FIXED_MTU="`expr $CURRENT_MTU + 4`"
ip link set $1 mtu $FIXED_MTU

After finish editing , do not forgot make it executable (chmod 770 /etc/ppp/ip-up.d/mppefixmtu.sh).

For reason of this issue refer this link: [2]