Stealth mode for HTTP proxy (HTTPPROXY_STEALTH)

[pokemaster974]

Hi, I've already installed gluetun but now I'm actually trying to create a HTTP proxy.
For now, I'm not certain of this option in https://github.com/qdm12/gluetun-wiki/blob/main/setup/options/http-proxy.md

"Stealth mode means HTTP proxy headers are not added to your requests"

Is it better to let it OFF (like as default) or is it better to switch it to ON ?
What's the pros and the cons of the 2 differents options ?

Regards.

[oalieno]

gluetun/internal/httpproxy/http.go

Line 28 in 6ac7ca4

if !h.stealth {

gluetun/internal/httpproxy/http.go

Lines 62 to 72 in 6ac7ca4

	func setForwardedHeaders(request *http.Request) {
	clientIP, _, err := net.SplitHostPort(request.RemoteAddr)
	if err != nil {
	return
	}
	// keep existing proxy headers
	if prior, ok := request.Header["X-Forwarded-For"]; ok {
	clientIP = fmt.Sprintf("%s,%s", strings.Join(prior, ", "), clientIP)
	}
	request.Header.Set("X-Forwarded-For", clientIP)
	}

According to the code, stealth mode means DO NOT add your ip to the X-Forwarded-For header. X-Forwarded-For is a HTTP header that contains multiple ips like 1.2.3.4, 2.3.4.5. It is a list that tracks all the ip all the way from source to destination (there might be multiple proxy server along the way).

If you leave the default (OFF), the destination server will receive something like the following.

GET / HTTP/1.1
Host: 1.2.3.4
User-Agent: curl/7.88.1
Accept: */*
X-Forwarded-For: 172.16.0.1
Accept-Encoding: gzip

The ip appears to be private ip 172.16.0.1 because I sent the request from my host machine to the docker inside. But you see the idea, your ip will be pass in the HTTP header. I think most people use gluetun for privacy, likely *arr apps. My recommendation is to turn it ON, no harm in turning this on.