New chapter of my router project if you don’t care to follow it you probably don’t want to read this at all.
Libero – or Infostrada, Wind, how the heck do you want to call it today – is my provider. Like other providers in Italy, who have probably noticed their users using OpenDNS instead of the standard DNS they provide, they started providing “captive redirects” on failed urls: when you mistype an URL or you try to access an hostname that does not exist, they redirect to their own servers, using their own “search engine” (nowadays just a Google frontend!).
This breaks quite a few assumption, included the fact that the .local domains won’t resolve in the standard DNS servers, which in turn makes nss-mdns almost unusable.
Up to a couple of months ago, Libero only provided this service in the primary nameserver, and if you switched around primary and secondary servers, you sidestepped the issue (that was the actual advertised procedure by the Libero staff, on the public page that was linked from within the search results). Unfortunately this had other side effects, for instance the time needed for the update of records more than doubled, which was quite boring with dynamic DNS and with newly-created domains.
Luckily, pdnsd supports blocking particular IP returned by the results to avoid the fake records created for captive redirects, and the example configuration file itself provides an example for using that with OpenDNS to avoid falling into their redirected Google host (quite evil of them in my opinion). And in particular, at the time, there was only one host used for captive redirect, so the rule was quite simple.
Fast forwards to today, the rule have changed; first of all it seems like Libero now uses redirects on both servers (or the secondary fails so often that it always responds from the primary), and most importantly they increased the number of IPs the redirects respond from. After counting four different IPs I decided to go with something more drastic, and ended up blacklisting the whole /24 network that they belong to (which is assigned, in RIPE, to Tiscali France… which is quite strange). I’m not sure if I ended up blacklisting more than I should have; for now it blacklists just enough for me to keep on browsing the net without adverse effects that I can see, and it also no longer stop me from enjoying .local domains… and Firefox auto-search with Google when the hostname does not exist.
For those interested, the configuration section is this one:
server {
label= “libero”;
ip = 193.70.152.15, 193.70.152.25;
proxy_only=on;
timeout=4;
reject = 195.210.87.131/32, 62.210.183.0/24;
}
The first IP (a single host) is the one that was used earlier, I keep it on the blacklist just to be on the safe side.