My work Firefox ESR browser seemed to be giving up my username (I.e., half of my login credentials) in its HTTP headers so I wrote simple Python-based webserver that mirrors the browser HTTP headers back to the browser. The script is encapsulated in a Docker image and could be deployed to an AWS instance. Here the server is started on common HTTP ports.

docker run --rm -d -p   80:8080 deanturpin/http
docker run --rm -d -p  443:8080 deanturpin/http
docker run --rm -d -p 8080:8080 deanturpin/http

Dockerfile

FROM ubuntu
RUN apt update --yes
RUN apt install --yes python
COPY . src
WORKDIR src
CMD ./serve.py

Python script

#!/usr/bin/env python

import SimpleHTTPServer
import SocketServer
import datetime

class Handler(SimpleHTTPServer.SimpleHTTPRequestHandler):

    def do_GET(self):

        # Set MIME type
        self.send_response(200)
        self.send_header('Content-Type', 'text/plain')
        self.end_headers()

        # Banner
        self.wfile.write("MIRROR BROWSER HEADERS - ")
        d = str(datetime.datetime.now())
        self.wfile.write(d)
        self.wfile.write("\n\n")

        # Dump HTTP headers supplied by browser
        for h in self.headers:
            self.wfile.write(h)
            self.wfile.write(" ")
            self.wfile.write(self.headers[h])
            self.wfile.write("\n")

httpd = SocketServer.TCPServer(("", 8080), Handler)

httpd.serve_forever()