[ars_technician]

Did you even read his comment?

"dig @www.facebook.com news.ycombinator.com" does not use the ISP's DNS servers at all. It sends a DNS query to Facebook for Google, which should normally fail. His ISP hijacks the request and provides a response. In this scenario, the advice in your comment is pointless because they will hijack requests whether they are directly to authoritative servers or if they are to recursive servers.

[gwu78]

Yes, I read his comment.

""dig @www.facebook.com news.ycombinator.com" does not use the ISP's DNS servers at all"

Incorrect. The program he's using, dig, has to look up the numbers for facebook.com's authoritative servers first. And what DNS servers do you think it uses to do that? The defaults he has set: his ISP's.

"It sends a DNS query to Facebook for Google."

Incorrect again.

The "advice" I provided is not pointless. I would not provide pointless suggestions.

[gwu78]

"What aren't you getting?"

I am glad you asked. I am not getting what it is you are trying to say. I also do not get why you keep mentioning Google.

"The query for Facebooks server may use the ISPs DNS server, but that's not the problem."

Why is that not the problem?

If you query the ISP's DNS servers, then the ISP can send you bogus answers. By giving you bogus answer they can redirect your HTTP requests, which enables them to insert ads, among other things. I presume you would want to avoid this. I gave examples how you could do that. One way is to run your own recursive DNS server on 127.0.0.1. Another is to only query the proper authoritative servers.

Shaw uses a "DNS Redirect service". Customers can opt out.

https://community.shaw.ca/docs/DOC-1218

Even if a customer does not disable this "service", I believe Shaw will not interfere with packets sent to remote DNS servers other than Shaw's.

In any event, the reason I commented on this was because (unless the customer has changed his defaults)

dig @www.facebook.com news.ycombinator.com

sends queries to Shaw's DNS servers. So stop doing this.

Unless the customer opts out, these queries are going to get redirected.

If you wanted to test your theory (that Shaw is redirecting every DNS packet sent by evey customer, even ones not using Shaw's DNS servers), then the above invocation of dig will not test this. It sends queries to the Shaw DNS servers. Stop doing that.

Why does it send queries to Shaw's DNS servers? From the dig(1) manpage:

"SIMPLE USAGE A typical invocation of dig looks like:

            dig @server name type

       where:

       server
           is the name or IP address of the name server to query. This can be
           an IPv4 address in dotted-decimal notation or an IPv6 address in
           colon-delimited notation. When the supplied server argument is a
           hostname, dig resolves that name before querying that name server.
           If no server argument is provided, dig consults /etc/resolv.conf
           and queries the name servers listed there. The reply from the name
           server that responds is displayed.

"

If for some reason you wanted to send a query for news.ycombinator.com to the IP address for www.facebook.com (without using any recursive DNS servers like Shaw's which could give you bogus answers), then

dig +norecurse @31.13.75.17 news.ycombinator.com

would be the appropriate way to do it, assuming you choose to use dig.

[aendruk]

Thanks for the explanation. Would you interpret these results as supporting evidence of my claim?

  $ dig +short chaos txt version.bind @31.13.75.17     
  "PowerDNS Recursor 3.5.3 $Id$"

This happens despite having opted out via the form you mentioned.

[gwu78]

Your claim was they are proxying "all" port 53 traffic.

In effect, you are saying no customer can query any DNS server except Shaw's.

That sounds a bit extreme.

I have more questions. Can you run some tests?

You say you use DNSCrypt. Can you try it with port 53? Maybe something like

  dnscrypt-proxy --resolver-port=53

and

  dnscrypt-proxy --resolver-port=53 --tcp-only

DNSCrypt is built using public domain software written by a maths professor: namely, djbdns and curvecp.

Now, without DNSCrypt, can you try using djbdns? For me at least, it is easier to understand what the software does. dig and the BIND libraries are far too complex for my liking.

Compile or get binaries for djbdns and use dnsq(1).

  dnsq a news.ycombinator.com 31.13.75.17

If you get no response immediately, wait at least 60 seconds for a time out.

Finally, compile or get binaries for drill(1) from NLnet Labs.

  drill -t news.ycombinator.com @31.13.75.17

  echo ". 1 in ns a.root.servers.net." > 1.tmp
  echo "a.root.servers.net. 1 a 198.41.0.4" >> 1.tmp

  echo > 2.tmp

  drill -4ord -r1.tmp -tc2.tmp news.ycombinator.com @31.13.75.17

I'm genuinely curious about your situation. Shaw is no doubt playing games with their DNS, but I'm still not convinced they are "proxy[ing] all port 53 traffic".

I know that some ISP's block all traffic sent to port 25. But they have a compelling reason and hence a justification for doing that. Not true with proxying traffic to port 53. There's no harm in customers using DNS servers besides Shaw's.

[aendruk]

I've done some more tests [1] as you suggested. It looks like Shaw is routing all UDP/53 traffic to their DNS servers; I'd not considered TCP earlier. My optimistic guess as to their motivation for using such an invasive technique is that it was easy for them to deploy.

  [1]: https://gist.github.com/0998a0dd2c0abca91c8b

[gwu78]

Personally, I do not use DNS much at all except to do periodic bulk lookups for new domains I might visit.

I store all the DNS info I'll ever use[1] in .cdb files and also in my /etc/hosts file.

I do this for speed reasons, because HOSTS or tinydns on 127.xxx.xxx.xxx is always faster than DNS. But if I had an ISP like yours, it would be a necessity for other reasons.

Shaw is actually interfering with their customers' ability to lookup IP numbers. This is the most basic of all internet services.

And no one is complaining?

Anyway, you could do bulk lookups with TCP and then store the DNS info locally. That could reduce if not elimibate your need for DNS.

I've always thought that there should be DNS servers that can handle pipelined TCP queries, and this is one reason why.

If the idea of bulk lookups and not using DNS otherwise sounds intriguing and you want some examples of scripts to do bulk lookups, e.g. for HN sites, let me know. It sounds like you could really benefit from reducing your dependence on DNS.

1. For example, all the IP addresses for sites that appear on HN.