how to "allow from hostname" in nginx config

Question

I'm currently doing this in my nginx.conf:

allow 1.2.3.4;
deny;

What I'd really like to do is this:

allow my.domain.name;
deny;

I.e., I want nginx to do an A record lookup on my.domain.name at the time of the request, and if it matches the IP that the request is coming from, then allow it. I don't see any built-in mechanism to do this however. Anybody have a native way to do this before I start coding something custom?

Answer 1

ngx_http_rdns_module does what you need: https://www.nginx.com/resources/wiki/modules/rdns/ (https://github.com/flant/nginx-http-rdns)

Summary

This module allows to make a reverse DNS (rDNS) lookup for incoming connection and provides simple access control of incoming hostname by allow/deny rules (similar to HttpAccessModule allow/deny directives; regular expressions are supported). Module works with the DNS server defined by the standard resolver directive.

Example

location / {
    resolver 127.0.0.1;

    rdns_deny badone\.example\.com;

    if ($http_user_agent ~* FooAgent) {
        rdns on;
    }

    if ($rdns_hostname ~* (foo\.example\.com)) {
        set $myvar foo;
    }

    #...
}

Answer 2

There is no such feature in official distribution of nginx. Beacause it may heavily reduce performance.

Third party modules http://wiki.nginx.org/3rdPartyModules also doesn't contain this feature.