Posts tagged nginx

Blocking user agents with nginx

My server has been attacked repeatedly by censys and some company called Expanse, from enough IPs that I need to look into range banning their networks. Doing so is logistically annoying, so obviously, the sane kneejerk response until then is to ban their user agents in nginx with a custom message out of spite.

It's fairly easy to do with a map and an if statement:

http {

    map $http_user_agent $blocked_ua {
        default 0;
        # Various organisations that attack servers, but seem to get away with doing so for some reason.
        # This list is not synced with my currently used list
        "~*censys" 1;
        "~*paloaltonetworks.com" 1;
    }

    server {
        # ... 
        if ($blocked_ua) {
            return 403 "Fuck off";
        }
    }

}

This needs to be configured on a per-server basis, because reasons.