Find the fastest server to disable comcast's DNS hijacking

sudo netselect -v -s3 $(curl -s http://dns.comcast.net/dns-ip-addresses2.php | egrep -o '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' | sort | uniq)
Comcast is an ISP in the United States that has started hijacking DNS requests as a "service" for its customers. For example, in Firefox, one used to be able to do a quick "I'm Feeling Lucky" Google search by typing a single word into the URL field, assuming the word is not an existing domain when surrounded by www.*.com. Comcast customers never receive the correct NX (non-existent domain) error from DNS. Instead, they are shown a page full of advertising. There is a way to "opt out" from their service, but that requires having the account password and the MAC address of your modem handy. For me, it was easier just to set static DNS servers. But the problem is, which ones to choose? That's what this command answers. It'll show you the three _non-hijacked_ Comcast DNS servers that are the shortest distance away. Perhaps you don't have Comcast (lucky you!), but hopefully this command can serve as an example of using netselect to find the fastest server from a list. Note that, although this example doesn't show it, netselect will actually perform the uniq and DNS resolution for you. Requires: netselect, curl, sort, uniq, grep
Sample Output
Running netselect to choose 3 out of 12 addresses.      
...........................................................................
   53 68.87.69.146
   62 68.87.76.178
  273 68.87.74.162

What Others Think

Update: Comcast no longer gives out the IP address of the advertisement free DNS servers, or if they do, it's not at the URL I have. I'll leave this command up as an example of using netselect, but it no longer does what I designed it to. Fortunately, there is an even better solution. Instead of using Comcast's servers, simply change your static DNS IPs to be 8.8.8.8 and 8.8.4.4. Those are public DNS servers run by Google which are very fast and work correctly (return NX for non existent domains instead of spam).
hackerb9 · 420 weeks and 4 days ago

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