I have just updated my laptop to fedora 21 OS. And had faced with the problem when trying to connect my office VPN (via point to point tunneling protocol - PPTP) with this error message **“connection process ends with timeout”. **If you have the same issue, type command below :

#sudo modprobe nf_conntrack_pptp

if you want to load nf_conntrack_pptp module automatically when your lap start up, type these commands:

#sudo touch /etc/modules-load.d/nf_conntrack_pptp.conf
#sudo echo "nf_conntrack_pptp" > /etc/modules-load.d/nf_conntrack_pptp.conf

You should change nf_conntrack_pptp.conf permisson to 771 if you have file permission error with the second command.

Reference link: https://support.hidemyass.com/hc/en-us/articles/202721566-PPTP-Setup-on-Fedora https://bugzilla.redhat.com/show_bug.cgi?id=1187328