How to find out the data that the script sends?

Question

PHP

There is a php site which is coded by ioncube. The site has a form that, through AJAX, accesses the script on the site, and it sends some data to another server. Tell me how to find out this data that this script sends.
We have centos 7 on the server.

Answer 1

monitoring outgoing requests and the request body from the script
// Accordingly, you need to install tcpdump on your centos.

Answer 2

decrypt the script, find out what's inside it.