mod_http_oauth2: Do minimal validation of private-use URI schemes Per draft-ietf-oauth-v2-1-08#section-2.3.1 > At a minimum, any private-use URI scheme that doesn't contain a period > character (.) SHOULD be rejected. Since this would rule out the OOB URI, which is useful for CLI tools and such without a built-in http server, it is explicitly allowed.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_whitelist",

}
s2s_whitelist = {
    "example.org",
}
```