Install PopTop PPTP server on CentOS

PopTop is an open-source PPTP VPN solution for Linux.

Here’s a rudimentary guide on how to install and configure it on CentOS/RHEL based distro. The RPMs I refer to are available on http://sourceforge.net/project/showfiles.php?group_id=44827.

Check kernel MPPE support

Check if kernel is already compiled with MPPE;
modprobe ppp-compress-18 && echo ok
If not ok, install the latest DKMS RPM and the latest kernel_ppp_mppe RPM.

Update PPP

Upgrade PPP to version 2.4.3 or later if necessary (remove first with yum remove ppp!!).

Install PPTPD

Install latest pptpd RPM, start pptdp service and make sures it starts on boot.

Enable IP forwarding

Enable IP forwarding in /etc/sysctl.conf:
net.ipv4.ip_forward = 1

Note: the change to sysctl.conf is effective on reboot, to make the change now
echo 1 > /proc/sys/net/ipv4/ip_forward

Configuration

You can follow the configuration docs on http://poptop.sourceforge.net/dox/. Make sure the assigned IPs are in the same subnet as the server IPs you want to access. The local IP should be outside this subnet.

Troubles?

  • Check the local IP and remote IP ranges. Local should be outside the ‘local’ subnet and the remote range should be inside your ‘local’ subnet.
  • Make sure you use the right syntax for providing the remote IP range.
  • Check /var/log/messages.