Idea is to have Zabbix Proxies deployed inside private networks connecting to Zabbix Server on internet. Actually, it is required to allow direct connection from Zabbix Proxy to Zabbix Server. Usually it would be so much easier if Zabbix Proxy could connect to Zabbix Server via a HTTP Proxy.

Although Zabbix protocol isn't HTTP, it is possible to use HTTP CONNECT method to establish a TLS tunnel thru standard HTTP Proxies with minimal changes, I guess, like `socat` does.

Feature Request 4310 is better but probably implementation is much more complex.