Our Lab bought a new server to build a web paltform (LAMP maybe, I am not involved in that) whose system is Centos 6.5. Centos maybe a great system yet not for our school's network.
In the campus, we connect to the Internet through l2tp VPN and xl2tpd is usually used.
We have customized deb package for xl2tpd containing specific options for the school network on the school forum. Unfortunately, no rpm package is provided.
I found a github project provide a solution for rpm package. But the problem is the package version is too new for Centos 6.5,
or rather too new for glibc. So the solution for Centos 6.5 is to use the xl2tp-1.2.8-1 package (or lower, I haven't test lower versions).
On pkgs.org/, we can find other xl2tpd versions.
There is a more detailed tutorial for l2tp vpn.
Chinese version
浙大校园网真是垃圾啊
Centos6.5下如何连接校园网
参见 https://github.com/xueshengke/ZJU-VPN ，有一个问题是xl2tpd的版本太新了，降到1.2.8就行了