Step 1

1. http://pptpclient.sourceforge.net/#download download the latest version of pptp Client
2. Upload your server.

Step 2

1. tar -zxvf your path
2. your path/pptpsetup --creat <vpnname> --server <vpn-ip> --username<> --password<>

Connect

your path/pppd call <vpnname>

Disconnect

killall pppd

Some note

1. make sure that your serve has installed the ppp
    #rpm -qa|grep ppp
2. ppp is in the disk of centos
    #rpm -ivh ./ppp-2.4.4-2.el5.i386.rpm