I recently needed to get a PPTP VPN connection working from a CentOS 7 machine to one of my clients. I'd gotten the same working from MINT Linux a few weeks earlier, and it was as simple as clicking the network icon on the toolbar, selecting VPN Connections -> Configure VPN, and adding a PPTP connection. I figured it would be equally simple on CentOS 7, but I was surprised to find that the list of VPN types didn't include PPTP.
This was confusing because NetworkManager-pptp and NetworkManager-pptp-gnome packages were both installed. Long story short... As of 10/23/18, CentOS 7 uses NetworkManager 1.10 and compatible versions of the PPTP-related RPMs aren't available in the CentoOS repos. If you want to get it working, you have to build and install new enough RPMs from source.
Steps to accomplish this follow...
Make sure NetworkManager-pptp and NetworkManager-pptp-gnome are installed, just to be sure that you have various dependencies installed as well:
sudo yum install NetworkManager-pptp NetworkManager-pptp-gnome
Set up an RPM-build environment (if you don't already have one set up). This is most easily done by installing the fedora-packager meta-package and running a handy script that it provides:
sudo yum install fedora-packager @development-tools rpmdev-setuptree
Note that rpmdev-setuptree wasn't run using sudo. This script should be run as you. It basically creates a .rpmmacro file and rpmbuild tree under your home directory.
Download a new enough source RPM for NetworkManager-pptp from somewhere. A new enough version is included in Fedora Core 28, for example:
wget https://dl.fedoraproject.org/pub/fedora/linux/updates/28/Everything/SRPMS/Packages/n/NetworkManager-pptp-1.2.8-1.fc28.src.rpm
Install packages that you'll need to build the RPMs:
sudo yum install glib2-devel gtk3-devel NetworkManager-libnm-devel libnma-devel ppp-devel libtool intltool libsecret-devel NetworkManager-devel NetworkManager-glib-evel libnm-gtk-devel
Build the RPMs:
rpmbuild --rebuild NetworkManager-pptp-1.2.8-1.fc28.src.rpm
And, finally, install the RPMs that you just built:
cd ~/rpmbuild/RPMS/x86_64 sudo yum install NetworkManager-pptp-1.2.8-1.el7.x86_64.rpm NetworkManager-pptp-gnome-1.2.8-1.el7.x86_64.rpm
(Of course, this assumes that you're building on an x86_64 host. Adjust the path and file names accordingly if you are not.)
At this point, if you try to create a new VPN connection, you should see "Point-to-Point Tunneling Protocol (PPTP)" in the list of available VPN types.
You can also safely remove NetworkManager-pptp-1.2.8-1.fc28.src.rpm at this point. If you don't think you'll be building any more RPMs any time soon, then you can also remove ~/.rpmmacros and the ~/rpmbuild tree. If you find that you do need to build more RPMs, then you can just rpmdev-setuptree again to re-setup the RPM-build environment.
Good luck!
