Steps to reproduce:

1. refer ZBX-6790, we config a custom script to listen port 
2. but when i user zabbix get it return 0 even if i sure that port is listening.

Result:
Compare to another vm , i think that script is not support tcp6

Expected:
For ZBX-6790, i think it is only for listen tcp port. so i need your help to provide a new script for tcp6.(/proc/net/tcp6)

thanks.