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# Reverse proxy

Nextcloud can be run through a reverse proxy, which can cache static assets such as images, CSS or JS files, move the load of handling HTTPS to a different server or load balance between multiple servers.

## Defining trusted proxies

For security, you must explicitly define the proxy servers that Nextcloud is to trust. Connections from trusted proxies will be specially treated to get the real client information, for use in access control and logging. Parameters are configured in `config/config.php`

Set the `trusted_proxies` parameter as an array of:

- IPv4 addresses,

- IPv4 ranges in CIDR notation

- IPv6 addresses

- host to resolve

to define the servers Nextcloud should trust as proxies. This parameter provides protection against client spoofing, and you should secure those servers as you would your Nextcloud server.

A reverse proxy can define HTTP headers with the original client IP address, and Nextcloud can use those headers to retrieve that IP address. Nextcloud uses the de-facto standard header ‘X-Forwarded-For’ by default, but this can be configured with the forwarded_for_headers parameter. This parameter is an array of PHP lookup strings, for example ‘X-Forwarded-For’ becomes ‘HTTP_X_FORWARDED_FOR’. Incorrectly setting this parameter may allow clients to spoof their IP address as visible to Nextcloud, even when going through the trusted proxy! The correct value for this parameter is dependent on your proxy software.

## Overwrite parameters

The automatic hostname, protocol or webroot detection of Nextcloud can fail in certain reverse proxy situations. This configuration allows the automatic detection to be manually overridden. If Nextcloud fails to automatically detect the hostname, protocol or webroot you can use the overwrite parameters inside the `config/config.php`.

- `overwritehost` set the hostname of the proxy. You can also specify a port.

- `overwriteprotocol` set the protocol of the proxy. You can choose between the two options http and https.

- `overwritewebroot` set the absolute web path of the proxy to the Nextcloud folder.

- `overwritecondaddr` overwrite the values dependent on the remote address. The value must be a regular expression of the IP addresses of the proxy. This is useful when you use a reverse SSL proxy only for https access and you want to use the automatic detection for http access.

Leave the value empty or omit the parameter to keep the automatic detection.

## Service Discovery

The redirects for CalDAV or CardDAV does not work if Nextcloud is running behind a reverse proxy. The recommended solution is that your reverse proxy does the redirects.

### Apache2

    RewriteEngine On
    RewriteRule ^/\.well-known/carddav https://%{SERVER_NAME}/remote.php/dav/ [R=301,L]
    RewriteRule ^/\.well-known/caldav https://%{SERVER_NAME}/remote.php/dav/ [R=301,L]

Thanks to @ffried for apache2 example.

### Traefik

    traefik.frontend.redirect.permanent: 'true'
    traefik.frontend.redirect.regex: https://(.*)/.well-known/(card|cal)dav
    traefik.frontend.redirect.replacement: https://$$1/remote.php/dav/

Thanks to @pauvos for traefik example.

## Example

### Multiple domains reverse SSL proxy

If you want to access your Nextcloud installation http://domain.tld/nextcloud via a multiple domains reverse SSL proxy https://ssl-proxy.tld/domain.tld/nextcloud with the IP address 10.0.0.1 you can set the following parameters inside the `config/config.php`.

    <?php
    $CONFIG = array (
      'trusted_proxies'   => ['10.0.0.1'],
      'overwritehost'     => 'ssl-proxy.tld',
      'overwriteprotocol' => 'https',
      'overwritewebroot'  => '/domain.tld/nextcloud',
      'overwritecondaddr' => '^10\.0\.0\.1$',
    );

Note

If you want to use the SSL proxy during installation you have to create the `config/config.php` otherwise you have to extend the existing $CONFIG array.

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