« Posts tagged DNS

Shaw Cable Pulls a Rogers; Hijacks NX Records

May 1, 2011 / posted in "It's a Feature", Hack, Networking / 5 Comments

Shaw CableThe last time I wrote about NX Domains, it was because I noticed that Rogers wireless was hijacking them on my phone. Now, it appears that Shaw Cable is doing the same.

I use OpenDNS, so I’m used to search pages coming up when I mistype URLs, however that is something I’d opt’ed in to. You can imagine my surprise when, after mistyping a URL, I was directed to this instead:

http://assist.shaw.ca/shawcaassist/dnsassist/main/?domain=www.example.com

(original URL redacted).

It appears that, even if you aren’t using Shaw’s DNS servers they are still checking your DNS requests and, in the case of NX domains (at least – they could technically do this for any traffic), hijacking the result and forwarding your browser to their page instead.

I’ve sent a barrage of messages to Shaw’s PR team on Twitter, but haven’t had a response yet. I’ll update this article when (or if) they reply.

For the time being, though, it appears you can opt-out of the ‘service’ using this page: http://nxr.shaw.ca/optout/

Update: I’ve had a reply from Shaw saying “We do not modify any DNS traffic going to our customers from other sources”. They’re currently looking in to the issue apparently, so another update will be in order when I hear back.

Additional Update: I received a reply from Shaw asking me to do some further troubleshooting, all of which would have been useless (eg, using the ‘dig’ and ‘nslookup’ commands to confirm my DNS settings and what the NX response was), however as I opted out of the ‘service’ I can’t actually complete the steps as everything is working correctly. Additionally, there doesn’t appear to be a way to opt back in to the ‘service’, so that’s also a bust. I guess I won’t be getting an answer as to what happened. Also, I was linked on Reddit Canada.

Logon Server Unavailable Error

August 18, 2010 / posted in Microsoft, Servers, Software, Troubleshooting, Windows / No Comments

I came back from vacation the other day to find that some computers on our primary domain (example.local) were unable to access shares on a secondary domain (test.local) located in another building, accessed via a wireless link). When attempting to open the share (or just browse to the Domain Controller), the following error would appear:

Share Error

"There are currently no logon servers available to service the logon request."

Google’ing did no good, as there were only vague references to DNS issues and WINS servers (the later of which we don’t use). As nothing had changed in the environment recently, I was at a bit of a loss. I could ping the DC (Homer) in question, and even RDP to it, but I couldn’t for the life of me access the share. NSLOOKUP behaved normally, but then I had a thought — the DC that I couldn’t access was also acting as a DNS server (the primary one for test.local) with example.local as a Secondary Zone (which, of course, contained the DNS entries for the computers that were having trouble accessing the secondary domain). When I loaded the DNS manager and clicked on that zone, I was immediately greeted with an error stating the following:

DNS Error

Turns out, there *was* a DNS problem!

The problem was that I had removed a DNS server over a year ago and it was still referenced as the primary DNS server for this zone. For some reason, the Windows DNS service had just now decided this was a problem and stopped grabbing copies of the zone from the functional secondary DNS server.

To fix this, I simply right-clicked on the zone, chose Properties, and then removed the offending server IP from the General tab and updated with the correct servers and order. As soon as I finished, the computers had no trouble accessing that DC again. Magic!