A hang of connecting VPN (L2TP) under Windows XP

I have a Linode CentOS7 server in my hand. I used a PPTP VPN for my own use.

The configuration is too troublesome, so I directly use the online script:

https://github.com/travislee8964/L2TP-VPN-installation-script-for-CentOS-7/blob/master/l2tp-ipsec-install-script-for-centos7.sh

I didn't have any machines to test, so I used an XP installed in VMWare, and then there were all kinds of tragic pits.

Configure the iptables of the Linode server, check the port, service, process L2TP and other services are normal, XP connection is normal, just when I was about to be happy, I suddenly found that Nima can't access the Internet!

Then began to check the server configuration, all kinds of no problem. Because I was not in a hurry to use it, I checked it off and on for several days, but it has not been resolved.

Later, I tried to connect to the VPN with my mobile phone, and it could be used. I remembered that it might be a problem with XP, and then the first article found by Google solved the problem:

https://www.joyvm.com/tutorials/win-xp-l2tp-setup

If you are using L2TP on Windows XP, you need this patch to work properly, this is because Windows XP L2TP does not support L2TP's IPSEC encryption . The method of use is very simple, download and decompress the patch package, double-click to import the registry patch and it will be OK

Or save the following content as l2tp.reg, double-click to import:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RasMan\Parameters]
"ProhibitIpSec"=dword:00000001

When there is a problem, I only think about the server, but I forgot to check the client, resulting in n days of unhappiness, pit