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Trusting Proxies

2.3 version
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Trusting Proxies


If you're using the Symfony Framework, start by reading How to Configure Symfony to Work behind a Load Balancer or a Reverse Proxy.

If you find yourself behind some sort of proxy - like a load balancer - then certain header information may be sent to you using special X-Forwarded-* headers. For example, the Host HTTP header is usually used to return the requested host. But when you're behind a proxy, the true host may be stored in a X-Forwarded-Host header.

Since HTTP headers can be spoofed, Symfony does not trust these proxy headers by default. If you are behind a proxy, you should manually whitelist your proxy.

New in version 2.3: CIDR notation support was introduced in Symfony 2.3, so you can whitelist whole subnets (e.g., fc00::/7).

use Symfony\Component\HttpFoundation\Request;

// only trust proxy headers coming from this IP addresses
Request::setTrustedProxies(array('', ''));

Configuring Header Names

By default, the following proxy headers are trusted:

If your reverse proxy uses a different header name for any of these, you can configure that header name via setTrustedHeaderName():

Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, 'X-Proxy-For');
Request::setTrustedHeaderName(Request::HEADER_CLIENT_HOST, 'X-Proxy-Host');
Request::setTrustedHeaderName(Request::HEADER_CLIENT_PORT, 'X-Proxy-Port');
Request::setTrustedHeaderName(Request::HEADER_CLIENT_PROTO, 'X-Proxy-Proto');

Not Trusting certain Headers

By default, if you whitelist your proxy's IP address, then all four headers listed above are trusted. If you need to trust some of these headers but not others, you can do that as well:

// disables trusting the ``X-Forwarded-Proto`` header, the default header is used
Request::setTrustedHeaderName(Request::HEADER_CLIENT_PROTO, '');

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.