Comcast Intercepts and Redirects Port 53 Traffic 527
An anonymous reader writes "An interesting (and profane) writeup of one frustrated user's discovery that Comcast is actually intercepting DNS requests bound for non-Comcast DNS servers and redirecting them to their own servers. I had obviously heard of the DNS hijacking for nonexistent domains, but I had no idea they'd actually prevent people from directly contacting their own DNS servers." If true, this is a pretty serious escalation in the Net Neutrality wars. Someone using Comcast, please replicate the simple experiment spelled out in the article and confirm or deny the truth of it. Also, it would be useful if someone using Comcast ran the ICSI Netalyzr and posted the resulting permalink in the comments.
Not happening to me (Score:5, Informative)
I'm a Comcast user, and I run a DNS server for a few private domains that only I use. I have not experienced this, and I just verified that it's not currently happening. I'm in California if that matters.
Re:Not happening to me (Score:5, Interesting)
I'm a Comcast user, and I run a DNS server for a few private domains that only I use
Are you running that and hoping that your dynamic IP address doesn't change or do you have a business account with a fixed IP? If it's a business account than I would assume that they aren't redirecting those but could still be redirecting on consumer accounts.
Re: (Score:2)
Also, I have road runner now and I don't have a static IP. I just have a dyndns.org hostname I use coupled with their IP update tool that keeps my IP updated. they have free accounts as long as they stay updated. ie. deleted after 30 days without an
Re: (Score:2)
Also, I have road runner now and I don't have a static IP. I just have a dyndns.org hostname I use coupled with their IP update tool that keeps my IP updated. they have free accounts as long as they stay updated. ie. deleted after 30 days without an update but I get nice emails reminding me 5 days in advance. He might be doing the same?
Not if he's using his nameserver as an authoritative nameserver for one or more domains. You can't list those by hostnames, you have to list them by IP address. That said, I don't know how Comcast works but my Roadrunner IP hasn't changed in over a year. That's one of the nice things about them vs. Verizon DSL, where it seems to change on a almost daily basis.
Re:Not happening to me (Score:5, Informative)
Comcast is using nearly off the shelf DHCP with really long expires times. When you get an IP, you'll have it for months, and usually don't loose it until those months have passed AND you reboot your equipment and get a new IP.
DSL on the other hand is using PPPoE (PPP over ethernet.) Every time it starts a new session it gets a new IP, completely independant of what it had before. And from my experience with ATT/Bellsouth it's not daily, it's hourly. Unlike a direct link, PPPoE must renegotiate every time there's a momentary signal loss, just like dialup would do.
From what I've read, they use PPPoE because it's the easiest way to enable/disable users in real time via a RADIUS server. Comcast has to use more complicated methods to kill accounts (in some places, even send out a truck to put on a filter)
Re: (Score:3, Informative)
DSL on the other hand is using PPPoE (PPP over ethernet.) Every time it starts a new session it gets a new IP, completely independant of what it had before. And from my experience with ATT/Bellsouth it's not daily, it's hourly.
Depends on where you are. With Qwest (and a local third party ISP) I've had the same IP number since I got the service, maybe 10 years ago. That's regular consumer-grade (1.5M/1.0M) DSL. The reverse DNS lookup gives a name that has my ISP username embedded into it.
Re: (Score:3, Informative)
I've had my Comcast IP (outside Boston) change about 2 or 3 times on me in the span of about 5 years. It doesn't happen often, but it does. I believe it's only been when they need to add capacity to an area.
Re:Not happening to me (Score:5, Interesting)
Funny,
Here are the results from a static IP:
--Knoxville.hfc.comcastbusiness.net --
--UDP access to remote DNS servers (port 53) appears to pass through a firewall or proxy.
The applet was unable to transmit an arbitrary request on this UDP port, but was able to transmit a legitimate DNS request, suggesting that a proxy or firewall intercepted and blocked the deliberately invalid request.
The applet was unable to directly request a large DNS response. This suggests that a proxy or firewall is unable to handle large extended DNS requests or fragmented UDP traffic.--
There might be some other issues here:
http://www.auditmypc.com/port/udp-port-53.asp [auditmypc.com]
Re: (Score:3, Informative)
I'm a Comcast user, and I run a DNS server for a few private domains that only I use
Are you running that and hoping that your dynamic IP address doesn't change or do you have a business account with a fixed IP?
My access is through Comcast, though like TFA's writer I get it from Earthlink, and I have a static IP with a consumer not a business account.
Falcon
Re:Not happening to me (Score:4, Informative)
Me too. I'm also in CA and it is not curently happening.
Re:Not happening to me (Score:5, Interesting)
Re:Not happening to me (Score:4, Informative)
Re:Not happening to me (Score:5, Insightful)
Isn't that the point of this outrage?
More like intercepting traffic that isn't destined for Comcast as if it were. You're not attempting to contact Comcast in any way, but that's where the traffic is ending up.
Let's say Comcast, for some reason, suddenly decides that your site should no longer be reachable (by name), they could start intercepting DNS requests for your site and returning domain not found. Or worse, redirecting you to a site they find more "suitable."
Re:Not happening to me (Score:5, Funny)
Or, more simply, query something you know doesn't exist (like asdfdsafdsafhdsds.com) against your server
Thanks alot. Now I'm going to get slashdotted.
Re:Not happening to me (Score:4, Funny)
> Or, more simply, query something you know doesn't exist (like asdfdsafdsafhdsds.com)
1) Quickly registered non-existing domain mentioned on Slashdot and put up an ad-serving site.
2) Wait for bored Slashdotters to try the link.
3) Profit.
Thanks Slashdot :-)
Re:Not happening to me (Score:5, Insightful)
Isn't that the point of this outrage? Getting typojacked when you try to go to a genuinely invalid URL?
Actually, no. We've been outraged about that before. It's one thing if I use someone's server and it typojacks me due to a wildcard entry in the name tables. The alleged behavior we're discussing actually prevents* the user from using another nameserver outside of that ISP in order to sidestep the problem.
* (well, makes more difficult, requiring tunneling or something like that)
For quite awhile I've had the feeling that DNS will eventually be brokered through P2P/DHTs/etc with digitally signed payloads, and this type of behavior only makes that idea more appropriate.
Re:Not happening to me (Score:5, Informative)
I'm certain. I sent a query to a DNS server that I control. I ran tcpdump on the DNS server and I could see the packets from my home IP address coming in with the query and the refusal going out (I asked the DNS server that I control to resolve yahoo.com, which it should refuse to do).
Re:Not happening to me (Score:5, Insightful)
Re:Not happening to me (Score:5, Informative)
The machine from which I sent the request is connected to a Comcast residential Cable Internet connection. The server at the other end is a virtual machine in a colo facility somewhere -- not a Comcast facility. And before anyone asks, I tried both tcp and udp requests with the same result (no interception, no transparent proxy).
Re:Not happening to me (Score:4, Interesting)
Except that he actually received and sent the packets on the server and verified as such.
Re:Not happening to me (Score:5, Funny)
Then that's even worse! It means Comcast must have hacked his server to falsify the logs! /s
Re:Not happening to me (Score:5, Informative)
They are blocking port 53 it appears here in Virginia.
--UDP access to remote DNS servers (port 53) appears to pass through a firewall or proxy.
The applet was unable to transmit an arbitrary request on this UDP port, but was able to transmit a legitimate DNS request, suggesting that a proxy or firewall intercepted and blocked the deliberately invalid request.
The applet was unable to directly request a large DNS response. This suggests that a proxy or firewall is unable to handle large extended DNS requests or fragmented UDP traffic.--
I don't know about them hijacking it though. I'm not sure what causing it yet.
Look this way for more info:
|
|
|
\
\
V
Re: (Score:3, Funny)
Why are people suddenly so obsessed with pointing to the reply button?
Re: (Score:3, Funny)
^
|
|
\
\
\
\
I clicked on that and all I got was a lousy web form.
Re: (Score:3, Interesting)
Re: (Score:3, Informative)
Re:Not happening to me (Score:4, Insightful)
This is retarded.
I point my router's DNS to OpenDNS.org and everything works great. If I type a BS domain I get the OpenDNS search page.
One idiot's Wordpress blog is enough to make it to the front page? I mean, I think Comcast is the devil incarnate, but there are plenty of legitimate reasons to hate them without making up BS stories.
Re: (Score:3, Informative)
Same here. I routinely test work DNS servers from home (on Comcast). They include non-public domains that will not resolve anywhere else. Other zones may differ from what the authoritative nameserver would answer.
They may be intercepting DNS somewhere, but not here in Atlanta.
Not happening here (Score:2, Informative)
I have several domains I run on a private DNS server that I access from my house using Comcast. I haven't experienced this. I'm in California if it matters.
I suppose users could tunnel DNS over some other port if they had to.
Re:Not happening here (Score:4, Interesting)
I suppose users could tunnel DNS over some other port if they had to.
I route all of my DNS requests through a VPN to the DNS server at my office. Not everybody has this luxury though. I wonder if OpenDNS would be inclined to set up a VPN solution for people stuck with an ISP as arrogant as Comcast?
Re:Not happening here (Score:5, Interesting)
I'm wondering how this post ever made it to the slashdot front page. I haven't RTFM, but as it's from the domain comcastfuckingwithyourport53traffic.wordpress.com I don't see any reason to lend it credence.
The comments to this story say a lot, almost as much as the domain the story links to. Somebody screwed up posting this.
Re: (Score:2)
I'm wondering how this post ever made it to the slashdot front page.
kdawson hadn't met his daily quota for posting FUD articles yet?
Re: (Score:3, Funny)
Re: (Score:3, Funny)
Somebody screwed up posting this.
Posted by kdawson on 02:11 PM -- Tuesday June 09 2009
Why am I not surprised.
Re: (Score:2)
Fuck! I'm going to poor every drop of booze in my house down the sink!
Comcast has rerouted your sink too, so that will only help them! Getting drunk in this case? Not one of their better evil plans...
DNSSEC? (Score:2)
Re:DNSSEC? (Score:5, Informative)
DNSSEC is validated at the resolver level. However, even if you run your own local DNS resolver, DNSSEC wouldn't come into play -- Comcast can simply strip the KEY/RRSIG records entirely before sending them to you -- leaving your resolver thinking that the zone has no DNSSEC records at all (at which point, they are blindly accepted as valid).
I'd imagine that there is an option somewhere in bind to only accept signed records (and if not, there will be eventually I'm sure), but even if Comcast wasn't futzing with your dataz, you wouldn't have a functional internet.
(I'm on comcast, and am not seeing this redirection. I also run a local DNS resolver.)
Fuck `Em All (Score:5, Funny)
When Comcast took over from Time Warner here, I bailed.
I mean, Time Warner is evil. AT&T (who I switched to), is evil.
But Comcast is Motherfucking Sith Lord EVIL.
Scary fucking eeeeevil. Nazi evil. RIAA evil.
Re:Fuck `Em All (Score:5, Funny)
So what are you trying to say?
C'mon man, stop beating around the bush and get to your point.
Re:Fuck `Em All (Score:5, Funny)
C'mon man, stop beating around the bush and get to your point.
It had something to do with star wars. The sith lord part tipped me off.
Re:Fuck `Em All (Score:5, Informative)
group sex with Oprah Winfrey, Rosie O'Donnell, Roseanne Barr and Chelsea Clinton
That's the absolute worst thing I've read in a long time.
Well done, sir.
Re: (Score:2)
Scary fucking eeeeevil. Nazi evil.
Yes, because hijacking your DNS packets and injecting RST packets to interfere with bittorrent is comparable to putting millions of people in ovens and trying to conquer Eurasia.......
Re:Fuck `Em All (Score:5, Funny)
Re: (Score:2)
Even Hitler started with baby steps
Re:Fuck `Em All (Score:5, Funny)
try democracy (Score:3, Informative)
Re: (Score:2, Funny)
That's the quickest Godwin proof I've seen in a while.
Re:Fuck `Em All (Score:4, Insightful)
TWX is MPAA, but not RIAA or cable (Score:3, Informative)
From your post, I don't think you're aware that Time Warner is actually one of the presiding members of the RIAA (and the MPAA).
Time Warner is a member of the MPAA. It is not a major record label; it spun off Time-Life Records [wikipedia.org] in 2003 and Warner Music Group [wikipedia.org] in February 2004. It is not a cable company; it spun off Time Warner Cable [wikipedia.org] in March 2009.
Re: (Score:2, Funny)
Re: (Score:2)
Re: (Score:3, Funny)
It's funny because Comcast has been the most reliable ISP I've ever had.
Well, Mussolini made the trains run on time.
(Next up, a Hirohito reference. Stay tuned!)
That's a negative (Score:5, Funny)
I really am hoping this is NOT a gullibility test (Score:2, Informative)
My connection is comcast for biz-- go crazy- I took out my last subnet
The ICSI Netalyzr Beta
Introduction Analysis Results
Result Summary
74-92-106-XXX-Philadelphia.hfc.comcastbusiness.net / 74.92.106.XXX
Recorded at 14:15 EDT (18:15 UTC) on Tue, June 09 2009. Permalink. Transcript.
Noteworthy Events
Minor Aberrations
Certain protocols are blocked in outbound traffic
Address-based Tests
NAT detection: NAT Detected
Your global IP address is 74.92.106.XXX while your local one is 192.168.15.XX. You are behind a NAT. Y
Comcast is not alone in this (Score:2)
I use Sprint Mobile Broadband at home and the last time I checked (several months ago), they were still intercepting and redirecting port 53 traffic.
Doesn't happen for me (Score:2)
with comcast in NJ.
Thn again I don't get advertising page IPs in response to non-existant names either.
DNS-Based Filtering (Score:2, Interesting)
If you want real Comcast fun... (Score:2)
Take a look at the packet loss on their Augusta, GA servers. Regularly, from 10 PM to 1 AM (or later), 50%+ packet loss.
I know because a buddy's radio show keeps crapping out, and it goes through there. But when I rebroadcast the show as a test (and don't go through that server), the issues don't happen.
But their L1 and L2 techs can't figure out the problem.
Comcast results in Houston, TX (Score:4, Informative)
Here are the ICSI results [berkeley.edu]. Results are from a PC behind a bog-standard Linksys WRT-54g, for what it's worth.
Not my field, but I see Direct TCP access to remote DNS servers (port 53) is allowed. I'll leave it to the networking experts to pick through the rest of the report.
errmm... (Score:3, Informative)
TCP is generally only used for excessively large requests or zone transfers
Tm
Hmmm... (Score:2)
Interesting side-note. Time Warner's DNS servers stopped working recently for my Playstation 3. I switched to OpenDNS and all is well, but does anyone have an idea what's going on here? I thought DNS was DNS.
NN wars? (Score:2)
The scary part (Score:2)
This practice effectively prohibits the use of alternative DNS roots, such as OpenNIC. In other words, it gives ICANN even stronger dominance over internet naming.
Not for me... (Score:2)
Comcast customer in Colorado, just outside of Boulder. Not happening here; I use OpenDNS and am definitely hitting their servers.
Netalyzer results (Score:3, Interesting)
http://netalyzr.icsi.berkeley.edu/restore/id=ae8199f5-18807-f5eeee66-ce59-42a4-8803 [berkeley.edu]
Note that my DNS servers are Level3 servers (4.2.2.2, 4.2.2.4) since they are much faster than Comcast DNS.
Damn! That may stop my plan...... (Score:4, Funny)
Re:Damn! That may stop my plan...... (Score:4, Interesting)
Have you heard of IP over DNS? The DNStunnel software sends IP packets as TXT records over a real DNS, the client sends data in the request itself. Since these are real resolvable DNS records, proxying port 53 won't work. When I tried this software, I could only get a single stream over the tunnel, so I ran SSH over the DNStunnel and used ssh to forward a TCP port that I then ran OpenVPN on. This actually works, but it is very slow. And I can imagine that people would eventually find out because the wifi provider's DNS cache will fill up with IP data.
Comcast results in PA. (Score:2)
Direct UDP access to remote DNS servers (port 53) is allowed.
Direct TCP access to remote DNS servers (port 53) is allowed.
My office is just outside of Philadelphia, so southeastern PA, for regional results.
OpenDNS (Score:2, Interesting)
A good friend of mine was using OpenDNS on Comcast and one day, without warning, his internet service was cut off.
When he called the phone rep said that Comcast had disabled his internet because he was not using their DNS server and that if he wanted to have Comcast as a provider he had no choice but to use DNS servers provided by DHCP!
Is this happening for ANYONE? (Score:5, Insightful)
Re: (Score:3, Informative)
This is probably your NAT. We see such behavior among random visitors, but not those restricted to Comcast, and only a few Comcast-based visitors show this behavior.
Falsely advertising "Internet access" (Score:2, Interesting)
Are you buying "Internet access" or something else? If you bought "Internet access" and you aren't getting it that's breach of contract. Odds are you are buying "partial Internet access as spelled out by the terms and conditions" which is probably not "Internet access."
Are they advertising "Internet access" or something else? If they are advertising "Internet access" and not delivering, that's false advertising. Unfortunately, it takes either deep pockets or a friend in your friendly neighborhood Attorn
Boston South Shore: Nope (Score:2)
;; connection timed out; no servers could be reached
This was tested on testserv.mydomain.com (doesn't exist) because I knew it wouldn't respond. I don't have an outside box to test it with, so while not 100% conclusive, according to this test I should still get a DNS response if Comcast is intercepting. ICSI Netalyzr shows the following:
Basic UDP access is available.
Direct UDP access to remote DNS servers (port 53) is allowed. The applet
If they worked maybe more people would use them (Score:2)
Was mostly a couple years ago, but even still, I had to keep a note of alternative DNS servers just in case Comcast's went on a fritz. Crazy annoying, and try explaining it to laymen!
Official Response (Score:4, Informative)
"Official Response" (Score:5, Insightful)
Re:"Official Response" (Score:5, Informative)
I'd watch what you call an 'Official Response' as many corporations have very strict rules about talking to the press, or making any binding claims to a general audience. Are you authorized for such communication?
Yes she is. She's handled one of my responses before. Recently corporations have started hiring "social networking" types to answer questions on places like twitter, facebook et al. It would Slashdot is another one of these venues.
Re:"Official Response" (Score:4, Funny)
Re: (Score:3, Funny)
Re: (Score:3, Informative)
Re:Official Response (Score:5, Insightful)
As one of the authors of Netalyzr... (Score:5, Interesting)
We have not seen any redirection issues with Comcast user's DNS settings.
Questions on netalyzr itself will be answered in this thread.
Re: (Score:3, Interesting)
Looks like wowway is hijacking www.google.com, capturing the search and then doing a 302 to the actual search page (?)
http://netalyzr.icsi.berkeley.edu/restore/id=4b65aebb-24385-1985f52c-c397-4cc4-b780 [berkeley.edu]
Re:As one of the authors of Netalyzr... (Score:5, Informative)
A colleague who knew about our launch told us we just got slashdotted.
We actually WANT to get slashdotted, because that helps us measure the network.
So let me see if I have this straight... (Score:5, Informative)
News for nerds, indeed.
Re:So let me see if I have this straight... (Score:5, Insightful)
Welcome to the new Media Democracy.
Test market? (Score:4, Interesting)
I don't see anyone else mentioning this, but it seems they could be using a particular area to test this "policy"
Re:Using OpenDNS on Comcast (Score:5, Informative)
Likewise in Southern New Jersey (and Philadelphia before this -- the very heart of Comcast darkness)
I get OpenDNS error pages for nonexistent domains.
Re: (Score:2)
Same here. Jersey Shore. OpenDNS is still working fine.
Re: (Score:2)
Me not so much a fan of OpenDNS. I prefer pointing my DNS @ L3's servers... 4.1.1.1-.6
I have Comcast Biz class (no cap, less snooping since there is a signed agreement dictating such - for me at least). I will check this when I have a chance.
Re: (Score:2)
You may want to change that. I remember seeing an article a few weeks back saying that L3 was going to implement some access restrictions on those to lower their traffic.
Disregard; ORSN is SK (Score:3, Informative)
Apparently the ORSN project has been shut down, at least for the moment, due to lack of involvement and resources.
Some of the servers continue to operate, but it was officially discontinued [dns-oarc.net] as of 31 Dec 2008. Too bad.
Re:Confirmed. (Score:4, Funny)
Tweet (Score:3, Interesting)
Re: (Score:2)
That confirms nothing.
Re:Just run BIND in your computer (Score:4, Informative)
And your recursive DNS server performs its own lookups via requests on port 53 to the root servers, which get intercepted by Comcast, ...
Re: (Score:2)
Not if they're reaching the OpenDNS guide page on typos.
Re: (Score:3, Insightful)
No...it's anti-anyonebutnormalcustomer behavior. The people running dns servers are probably 0.000001% of internet users....the rest are probably just infected machines.
The question is *why* do they care about filtering DNS traffic? Do they offer this service as a paid service elsewhere, costing them *money*? Or is it simply to try to get a handle on worms and malware, which uses tons of bandwidth for a network as big as comcast, costing them *tons of money*.
They have a profit based mindset...it shouldn't b
Re:Not surprised (Score:4, Insightful)
The only way I can imagine they'd profit from this is by blocking access to alternative DNS servers like OpenDNS, or even just putting in well-known public DNS servers like 4.2.2.2, so that they can intercept unknown requests and return ad-laden pages instead. Basically typosquatting.
Various ISPs have gone down this road before. (Rogers Cable [slashdot.org] has tried, and so has Road Runner [slashdot.org].) Unfortunately -- for the shady ISPs, anyway -- it's easy for annoyed users to get around these schemes; they can just configure their computer or NATing router to use a different DNS server besides the one supplied by the ISP via DHCP.
By transparently redirecting all DNS requests to their own servers, Comcast would eliminate this method of circumventing their advertising. They could also block sites at the DNS level much more easily than before.
A lot of censorship schemes (ab)use DNS in order to return a bogus result to a query; these schemes aren't very good, though, because any user with two brain cells to rub together and the tiniest bit of motivation can change their DNS configuration to use clean servers instead. By doing transparent redirection, you prevent this.
Those strike me as the two obvious reasons. The profit-motivated one (squatting on failed DNS queries) is annoying and causes many non-web applications to fail or behave improperly, but it's not nearly as bad as the censorship-motivated one is. However, the same technique that makes failed-lookup ads harder to avoid could easily be used as part of a censorship scheme if demanded by the government. It's important that even casual Internet users (who may not really care about returning a "page not found" web page instead of the normal browser message) understand why letting their ISP monkey with DNS lookups is a Really Bad Idea.
In both cases you can get around the hijacking by using a VPN and forcing DNS queries though it, but that's significantly harder than changing from automatically-assigned DNS servers to well-known ones like OpenDNS's or Verisign's.
Re:Port 53 Rerouted in Seattle :| (Score:4, Informative)
Your netalyzr results show no DNS issues in the link you posted, using a Comcast DNS server: