if an HTTP client reaches a website through a proxy (not reverse proxy) server, what are the actual HTTP request and its parameters that are sent from this client host to the internet?
for example:
Proxy Server: www.proxy.com:80
Target website: www.website.com:8081
Does the HTTP client send the following Get request?
Get http://www.proxy.com:80
Host: www.proxy.com:80
OR
Get http://www.website.com:8081
Host: www.website.com:8081
if the first case is true, How can the proxy know what is the actual destination to forward this request?
otherwise, if the second is true, how can the request actually reach the proxy host machine?
When you want to issue a GET request to http://www.example.com:8081/index.html, the browser connects to www.example.com:8081 and sends the following request:
GET /index.html HTTP/1.1
Host: www.example.com:8081
Now when a proxy is configured, say www.proxy.com:80, the browser will connect to www.proxy.com:80 instead, and issue the following request:
GET http://www.example.com:8081/index.html HTTP/1.1
Host: www.example.com:8081
So when a proxy is configured, the HTTP client connects to the proxy instead of to the target server, and sends the request using the absolute URI.
The client doesn't have to change the HTTP request for it to be sent to a proxy. It has to change the TCP headers.
The screenshot below shows a HTTP request sent from my browser to a proxy, as you can see nothing in the HTTP request itself specifies the proxy.
How this works is the browser/client will issue a HTTP GET request, which will then be forwarded to the TCP/IP stack and wrapped in a TCP header. The TCP header is where the destination is specified (proxy or otherwise).
Http proxy server can read http headers.
Whenever we use http proxy the destination address in the tcp packet(originating from client) has destination address of proxy server..
When the proxy server receives the tcp packet it can read the http headers(which is present in tcp packet payload) the http headers contains the actual destination for the packet.. using this information the http proxy server can forward the packet to actual destination.
Source : https://www.ibm.com/support/knowledgecenter/SSBLQQ_9.1.0/com.ibm.rational.ritpp.install.doc/topics/c_ritpp_advanced_proxy.html
Related
I want to set up a custom proxy that proxies connections to some destinations (inside a network) but not other destinations (in the global internet). Is there any HTTP response the proxy server can send to make the browser connect directly to the requested destination?
For example, I request redirection to Google to my proxy server. The proxy server decides not to proxy, so I get this HTTP response, and my browser connects directly to Google.
You could send a redirect http response code like 302 to redirect the client directly to the website. See: https://moz.com/learn/seo/redirection
We are trying to make a secure communication between our embedded system and web server.Firstly we implement HTTP connection to in our microcontroller. I am just connecting to 80 port of my web server and send simple GET request to this port as example below :
GET /foo.php?msg=test HTTP/1.1
HOST: foo.com
My questions is,How we will turn this to HTTPS ? Which port i should connect ?
Will be any difference on structure of GET request above ? Will i have to do some encryption manually or connect to "https" link instead "http" is enuogh for secure communication.
Thanks for any information
The only difference between a HTTP request and a HTTPS request is that the first is send over a plain TCP connection while the other is send over a TLS connection, i.e.:
with HTTP you establish a TCP connection and send the request over this connection
with HTTPS you establish a TCP connection, upgrade this connection to TLS (including proper certificate validation etc!) and then send the same request as you did with HTTP over this connection.
Apart from that I recommend to either use an established library for HTTP or carefully read the standard. Although HTTP looks simply it is actually not and there are many questions here where users try to do a simply HTTP request and trip over behavior they did not expect.
For example in your case the server might send the response with chunked encoding, with content-length or simply end it with connection close. And it might wait for further requests on the same connection since HTTP/1.1 implicitly enables HTTP keep-alive. Does your code really account for all these cases?
I am using haproxy in front of my web-server for ssl termination.
I am forwarding request on port 81 if request is https and 80 if request is normal http-
backend b1_http
mode http
server bkend_server
backend b1_https
mode http
server bkend_server:81
Problem is, when haproxy sends request to back-end, it sends HTTP_HOST header as request.domain.com:81.
Is it possible in haproxy that I can send https request to back-end at specific port without appending the port in HTTP_HOST request header?
There are two issues, here.
First, there is no HTTP_HOST header. The header is Host:. It sounds like HTTP_HOST is something being generated internally by your web server or framework.
Second, HAProxy doesn't modify the Host: header just because your back-end is listening on a port other than 80. It doesn't actually modify the Host: header at all, unless explicit configured to, using a mechanism like reqirep ^Host: ... or http-request set-header host ....
You can confirm this with a packet capture. You should find that whatever HTTP_HOST is, the value is necessarily being generated internally on the back-end system itself, because it's not coming from HAProxy.
I created on golang double HTTP proxy server. Server receives request, adds additional headers in this request and sends this changed request to another proxy server, which read this headers, remove it from request, and finally make request into destination.
With HTTP it works perfect. But how create this with HTTPS ?!
In HTTPS request browser send http CONNECT request, and then send encrypted data. Can i decrypted this data with CA signed server certificate, then add headers, send HTTPS request to another server, and then send HTTPS request to destination !?
Imagine a webbrowser that makes an HTTP request to a remote server, such as site.example.com
If the browser is then configured to use a proxy server, let's call it proxy.example.com using port 8080, in which ways are the request now different?
Obviously the request is now sent to proxy.example.com:8080, but there must surely be other changes to enable the proxy to make a request to the original url?
RFC 7230 - Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing, Section 5.3.2. absolute-form:
When making a request to a proxy, other than a CONNECT or server-wide
OPTIONS request (as detailed below), a client MUST send the target
URI in absolute-form as the request-target.
absolute-form = absolute-URI
The proxy is requested to either service that request from a valid
cache, if possible, or make the same request on the client's behalf
to either the next inbound proxy server or directly to the origin
server indicated by the request-target. Requirements on such
"forwarding" of messages are defined in Section 5.7.
An example absolute-form of request-line would be:
GET http://www.example.org/pub/WWW/TheProject.html HTTP/1.1
So, without proxy, the connection is made to www.example.org:80:
GET /pub/WWW/TheProject.html HTTP/1.1
Host: www.example.org
With proxy it is made to proxy.example.com:8080:
GET http://www.example.org/pub/WWW/TheProject.html HTTP/1.1
Host: www.example.org
Where in the latter case the Host header is optional (for HTTP/1.0 clients), and must be recalculated by the proxy anyway.
The proxy simply makes the request on behalf of the original client. Hence the name "proxy", the same meaning as in legalese. The browser sends their request to the proxy, the proxy makes a request to the requested server (or not, depending on whether the proxy wants to forward this request or deny it), the server returns a response to the proxy, the proxy returns the response to the original client. There's no fundamental difference in what the server will see, except for the fact that the originating client will appear to be the proxy server. The proxy may or may not alter the request, and it may or may not cache it; meaning the server may not receive a request at all if the proxy decides to deliver a cached version instead.