What is X-Forwarded-For in Apache HTTP Server?

What is an X-forwarded Host used for?

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Host headers are the information your browser passes to. The origin site when visiting a web page. When your browser is configured properly, all your browser's. Visited sites (or the origin sites of all embedded. Webpages) will be visible to others by viewing your IP. Address from the location of the site. You may wish to refer to an FAQ entry on this subject if you have other. Questions. I use my Host a lot, why do I have to change it? ================================================. For security reasons, web servers protect your user-. Specific data (like your account number, and credit card. Number, etc. They can also restrict that user from accessing other parts of your site that they shouldn't see. (unless that user has been verified as being properly. Configured). In this case, you will generally have to change your Host to keep your user-specific. Credentials from being shared with others by observing. That HTTP header while connected to that particular. All clients whose connections were intercepted will have. Been assigned a random X-Client-IP-Address by. The server. Any requests to that server which contain information within the X-Client-IP-Address header will be. Attributed to the client with that IP address. All the other HTTP headers are attached to the original IP. The origin server is the server which the user wishes to. Be associated with. This can be thought of as either The physical location of the site or the network IP address. Of the server. It can also be thought of as a single IP address if the site hosts a single document but is. Accessible over many different physical servers or IP. Addresses. If a web document contains a hostname within it and the user can correctly type it into his browser. This would mean that the client (or user) wishes to visit. The site at that hostname. Note: If this is a virtual host, then multiple IP addresses may be served from a. Single virtual host and so multiple documents may be. Served from a single IP address.

What is X-Forwarded-For in Apache error log format?

For me it always comes in the error log as: remote IP X.

X My server's address X.X I'm curious if anyone can shed some light on what it means. I'm assuming it has something to do with the proxy server we use. If that's not right, what else could it mean? Thanks!
X-Forwarded-For is what appears in Apache's access log when an external client is connecting through a proxy (such as squid). If you're just using http or ftp, and you're behind a proxy, they will be recorded there and elsewhere in the logs as originating from the proxy server.

What is my IP X-Forwarded-For?

When you forward a request from one client to another, the forwarding IP is generally appended to the original request in some way.

One common way this happens is that you add x-forwarded-for='x.z.u' to the HTTP header. This is the address of the end-user as they see it when the request hits the router, or it can be a private network address you define and have DNS for. This has been an excellent option to secure applications from traffic snooping and MITM attacks.

Using X-Forwarded-For, your application can determine the address of the end user that received the request. You can even make assumptions based on the IP of the sender/forwarding client; however, the IP of the sender/forwarding client may not tell the whole story. For instance, there are ways to hide an IP address using NAT such that the client appears to be on a different network. Another example is if your end user's connection has poor network performance, that can result in an IP address being "slow" or changing over time.

You should really only trust the IP of the end user as the true indicator of who the actual source IP address is. For this tutorial, we will be using an example server listening on port 3000 with both Apache and Nginx (with Apache Reverse Proxy capabilities). We will also assume a NAT firewall (in practice, this is usually a VPN that gives us IP access to the inside world of our networks).

We will now build a test setup with Docker that will listen on port 9000 and will forward all incoming requests to port 3000. The request will then go through reverse proxying via Apache to port 8000. Let's take a look!

First, you will need to run some commands to setup the services. The following Dockerfile tells Apache to bind the port 9000 to host :3000, the IP address is set to 10.1 (the IP you get from ifconfig ) so you have access to it directly and the container IP address is 192.168.50.128 . This allows any external IP to access port 9000 via reverse proxy to port 3000 .

FROM ubuntu:latest RUN apt-get update && apt-get upgrade -y RUN apt-get install -y python3-dev build-essential supervisor COPY .