This is only used for case study , please DON'T USE it for any others.
#Step1: Curl the script in your own workspace .
#Step2: Update the configuration: YOUR_IPSEC_PSK='' YOUR_USERNAME='' YOUR_PASSWORD=''
#Step3: sh VPNsetup.sh
#Step4: Remember to open below port : 500 and 4500 500 isakmp 互联网安全关联和钥匙管理协议（ISAKMP） 4500 ipsec vpn