what is https and http tunnel methods in proxy?

Question

This image is ProxyDroid application and I saw some proxy soft wares like these one.

I find some free servers for http method (http proxy the famous one) and find servers for socks 4 and 5 but I cant find any server that support https and http tunnel and in other word I cant understand what are exactly these protocols.

Answer 1

Proxying HTTPS is done with a HTTP proxy by using the CONNECT request. Using this request the HTTP proxy is instructed to create a tunnel to the target server. Inside this tunnel the client can the do the TLS handshake needed for HTTPS:

> CONNECT example.org:443 HTTP/1.0
>

... proxy established TCP connection to example.org:443 ...

< HTTP/1.0 200 Connection established
<

... tunnel to target established
... proxy forwards data between client and target unchanged
<-> TLS handshake
<-> application data protected by TLS

HTTP tunnel is similar. Normally a HTTP request gets proxied by sending a HTTP proxy request:

> GET http://example.org/index.html HTTP/1.0
> Host: example.org
>

... proxy connects to target example.org and forwards request
... then sends response from target server back

< HTTP/1.0 200 ok
< Content-length: ...
< ...

With HTTP tunnel the client instead uses the CONNECT method described above to create a tunnel to the target server and send the request:

> CONNECT example.org:80 HTTP/1.0
>
< HTTP/1.0 200 Connection established
<

... tunnel established, send HTTP request over tunnel and get reply back

> GET /index.html HTTP/1.0
> Host: example.org
> ...
< HTTP/1.0 200 ok
< ...