Access Control

fabio supports basic ip centric access control per route. You may specify one of allow or deny options per route to control access. Currently only source ip control is available.

To allow access to a route from clients within the and fe80::/10 subnet you would add the following option:


With this specified only clients sourced from those two subnets will be allowed. All other requests to that route will be denied.

Inversely, to deny a specific set of clients you can use the following option syntax:


With this configuration access will be denied to any clients with the fe80::1234 address or coming from the network.

Single host addresses (addresses without a prefix) will have a /32 prefix, for IPv4, or a /128 prefix, for IPv6, added automatically. That means is equivalent to and fe80::1234 is equivalent to fe80::1234/128 when specifying address blocks for allow or deny rules.

The source ip used for validation against the defined ruleset is taken from information available in the request.

For HTTP requests the client RemoteAddr is always validated followed by all elements of the X-Forwarded-For header, if present. When all of these elements match an allow the request will be allowed; similarly when any element matches a deny the request will be denied.

For TCP requests the source address of the network socket is used as the sole paramater for validation.

If the inbound connection uses the PROXY protocol to transmit the true source address of the client then it will be used for both HTTP and TCP connections for validating access.