I've been trying to use HTTPS whenever I do sensitive web browsing through a proxy server. Ideally I use a combination of HTTPS, an anonymous or elite proxy, and DuckDuckGo for all my web searches. Recently I encountered a problem with this though. Up until now, I've had no problem forcing HTTPS when I connect to a proxy, but just now I started getting a "400: Connection Refused" error when I do this. I used NMap to see which ports were open on the proxy.
sudo nmap -p 1-1024 -sX 0.0.0.0 Nmap scan report for 0.0.0.0 Host is up (0.092s latency). All 1024 scanned ports on 0.0.0.0 are open|filtered Nmap done: 1 IP address (1 host up) scanned in 96.98 seconds
So all ports are open, including 443, so I should be able to do it. I got this error for every proxy I tried, so it seems to be a problem at my end. The NMap output suggests that it may have something to do with the firewall. Also, I was able to telnet to port 80 but not 443.
So basically my question is, why is this happening, and how do I resolve it?