I am trying to install VPN tunnel through SMPP on my centos server and need help or some tutorial which shows how to do it.
I think what you want to achieve it create a VPN tunnel connection form your system/server to another system/server that has SMPP installed
Brief Information on VPN : http://www.centos.org/docs/5/html/Deployment_Guide-en-US/ch-vpn.html
it does not matter if its HTTP , SMTP , SMPP , or simple socket solution .. when you have a VPN connection you an force all traffic to use that connection
Tutorials on VPN Installation
http://blog.secaserver.com/2011/10/install-vpn-pptp-server-centos-6/
http://pctechnic.wordpress.com/2008/08/29/how-to-install-vpn-on-centos-45-in-3-minites/
http://www.howtoforge.com/openvpn-server-on-centos-5.2
http://www.rockia.com/2010/10/easy-installation-of-pptp-vpn-server-on-centos
I hope this helps
Thanks :)