Rich Wilson | 3 Apr 2011 08:09
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OT Strange dns behavior

Perhaps those with more knowledge than I can help me understand

the following behavior. It appears that opendns doesn't supply one of
their own addresses correctly. Sorry for the funny prompt (hence OT), 
but the same thing does happen in Linux.

----------------------------------------------------------------------------------------
C:\Users\rw>nslookup www-files.opendns.com 208.67.222.222
Address:  208.67.222.222

Non-authoritative answer:
Address:  204.194.237.142  <=============================


C:\Users\rw>nslookup www-files.opendns.com 8.8.8.8
Address:  8.8.8.8

Non-authoritative answer:
Address:  208.67.216.142 <=============================
--------------------------------------------------------------------

It appears that if I ask for a dns lookup of www-files.opendns.com, I get the wrong
answer from the opendns server. But only some people have this problem. With  
n=3 so far, only frontier.com customers have this problem. The result is that the
opendns.com web site does not display at all, or incorrectly after a long delay.

It gets even stranger with the following result:

------------------------------------------------------------------------------
C:\Users\Tom>nslookup www-files.opendns.com
Server:  Wireless_Broadband_Router.ftrdhcpuser.net
Address:  192.168.1.1

Non-authoritative answer:
Name:    www-files.opendns.com
Address:  208.67.216.142


C:\Users\Tom>nslookup www-files.opendns.com 208.67.222.222
Server:  resolver1.opendns.com
Address:  208.67.222.222

Non-authoritative answer:
Name:    www-files.opendns.com.ftrdhcpuser.net
Address:  67.215.66.132 <========================= !!
--------------------------------------------------------------------------------

The supplied address doesn't even have the same name!

The first result (rw) is frontier DSL, and the second (Tom) frontier FIOS.

I'm curious whether other frontier customers see the same behavior,
and whether all non-frontier customers see correct behavior.

How can this behavior be explained? Who's to blame? opendns? frontier? 
My queries to opendns have met with the "we're perfect, you're doing
something wrong" response.

(If this looks familiar, I asked a similar question on SLL when I knew less.
I'm asking here with the likelihood that there are more frontier customers
present, and perhaps n can be enlarged.)

Rich
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richaw <at> gmail.com

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Fred Morris | 3 Apr 2011 22:03

Re: OT Strange dns behavior

The short answer is that in terms of DNS behavior, it's giving the "correct" 
answer: there is nothing inconsistent in the DNS to explain it. (For good 
measure I have access to a special tool which checks on a 10 minute window, 
and the domain (essentially NS record check) opendns.com and hostname (A 
record check) www.opendns.com are in there, and neither has shown any 
anomalies in the last 30 days.)

On Saturday 02 April 2011 23:09, Rich Wilson wrote:
> Perhaps those with more knowledge than I can help me understand
> the following behavior. It appears that opendns doesn't supply one of
> their own addresses correctly.
> [...]
> C:\Users\rw>nslookup www-files.opendns.com 208.67.222.222
> Server:  resolver1.opendns.com
> Address:  208.67.222.222

The first observation I would make is that 
resolver1.opendns.com/208.67.222.222 is *not* an auth nameserver for the 
domain|:

m3047 <at> hera:~> dig com ns

; <<>> DiG 9.7.2-P2 <<>> com ns
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28641
;; flags: qr rd ra; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;com.                           IN      NS

;; ANSWER SECTION:
com.                    172800  IN      NS      g.gtld-servers.net.
com.                    172800  IN      NS      h.gtld-servers.net.
[...]

m3047 <at> hera:~> dig  <at> g.gtld-servers.net opendns.com ns +norecurse

; <<>> DiG 9.7.2-P2 <<>>  <at> g.gtld-servers.net opendns.com ns +norecurse
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27803
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 3, ADDITIONAL: 3

;; QUESTION SECTION:
;opendns.com.                   IN      NS

;; AUTHORITY SECTION:
opendns.com.            172800  IN      NS      auth1.opendns.com.
opendns.com.            172800  IN      NS      auth2.opendns.com.
opendns.com.            172800  IN      NS      auth3.opendns.com.

;; ADDITIONAL SECTION:
auth1.opendns.com.      172800  IN      A       208.69.39.2
auth2.opendns.com.      172800  IN      A       67.215.68.68
auth3.opendns.com.      172800  IN      A       208.69.39.2

[...]

Their servers are consistent:

m3047 <at> hera:~> dig  <at> auth1.opendns.com opendns.com ns +norecurse

[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10878
;; flags: qr aa; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 3

;; QUESTION SECTION:
;opendns.com.                   IN      NS

;; ANSWER SECTION:
opendns.com.            86400   IN      NS      auth1.opendns.com.
opendns.com.            86400   IN      NS      auth2.opendns.com.
opendns.com.            86400   IN      NS      auth3.opendns.com.

;; ADDITIONAL SECTION:
auth1.opendns.com.      3600    IN      A       208.69.39.2
auth2.opendns.com.      3600    IN      A       67.215.68.68
auth3.opendns.com.      3600    IN      A       208.69.39.2

;; Query time: 64 msec
;; SERVER: 208.69.39.2#53(208.69.39.2)
;; WHEN: Sun Apr  3 12:17:18 2011
;; MSG SIZE  rcvd: 137

m3047 <at> hera:~> dig  <at> auth2.opendns.com opendns.com ns +norecurse

[...]

;; QUESTION SECTION:
;opendns.com.                   IN      NS

;; ANSWER SECTION:
opendns.com.            86400   IN      NS      auth1.opendns.com.
opendns.com.            86400   IN      NS      auth2.opendns.com.
opendns.com.            86400   IN      NS      auth3.opendns.com.

[...]

;; Query time: 64 msec
;; SERVER: 67.215.68.68#53(67.215.68.68)
;; WHEN: Sun Apr  3 12:17:25 2011
;; MSG SIZE  rcvd: 137

m3047 <at> hera:~> dig  <at> auth3.opendns.com opendns.com ns +norecurse

[...]

;; QUESTION SECTION:
;opendns.com.                   IN      NS

;; ANSWER SECTION:
opendns.com.            86400   IN      NS      auth1.opendns.com.
opendns.com.            86400   IN      NS      auth2.opendns.com.
opendns.com.            86400   IN      NS      auth3.opendns.com.

[...]
;; SERVER: 208.69.39.2#53(208.69.39.2)

> Non-authoritative answer:
> Name:    www-files.opendns.com
> Address:  204.194.237.142  <=============================
> 
> C:\Users\rw>nslookup www-files.opendns.com 8.8.8.8
> Server:  google-public-dns-a.google.com
> [...]
> Name:    www-files.opendns.com
> Address:  208.67.216.142 <=============================
> [...]
> The result is
> that the
> opendns.com web site does not display at all, or incorrectly after a long
> delay.
> [...] 

Hold that thought...

> C:\Users\Tom>nslookup www-files.opendns.com
> Server:  
Wireless_Broadband_Router.ftrdhcpuser.net<http://wireless_broadband_router.ftrdhcpuser.net/>
> Address:  192.168.1.1
> 
> Non-authoritative answer:
> Name:    www-files.opendns.com
> Address:  208.67.216.142

Everything you've demonstrated so far is consistent, and consistent with what 
I get:

m3047 <at> hera:~> dig  <at> auth3.opendns.com www-files.opendns.com a +norecurse
[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25637
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3
[...]
;; ANSWER SECTION:
www-files.opendns.com.  3600    IN      A       208.67.216.142
[...]

m3047 <at> hera:~> dig  <at> auth2.opendns.com www-files.opendns.com a +norecurse
[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34835
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3
[...]
;; ANSWER SECTION:
www-files.opendns.com.  3600    IN      A       208.67.216.142
[...]

m3047 <at> hera:~> dig  <at> auth1.opendns.com www-files.opendns.com a +norecurse
[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13563
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3
[...]
;; ANSWER SECTION:
www-files.opendns.com.  3600    IN      A       208.67.216.142
[...]

m3047 <at> hera:~> dig  <at> 8.8.8.8 www-files.opendns.com a +norecurse
[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 64780
;; flags: qr ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
[...]
;; ANSWER SECTION:
www-files.opendns.com.  3198    IN      A       208.67.216.142

> C:\Users\Tom>nslookup www-files.opendns.com 208.67.222.222
> Server:  resolver1.opendns.com
> Address:  208.67.222.222
> 
> Non-authoritative answer:
> Name:    www-files.opendns.com.ftrdhcpuser.net
> Address:  67.215.66.132

As noted, that is not one of their auth (or even stealth) nameservers. What I 
get is this:

m3047 <at> hera:~> dig  <at> 208.67.222.222 www-files.opendns.com a +norecurse

; <<>> DiG 9.7.2-P2 <<>>  <at> 208.67.222.222 www-files.opendns.com a +norecurse
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 61314
;; flags: qr ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www-files.opendns.com.         IN      A

;; Query time: 46 msec
;; SERVER: 208.67.222.222#53(208.67.222.222)
;; WHEN: Sun Apr  3 12:20:45 2011
;; MSG SIZE  rcvd: 39

I don't know for a fact, but I find that perfectly reasonable if that's a 
caching resolver that they make available for specific users. They might do 
that by address block or some other means.

Now this is a bit of amusing graffitti:

m3047 <at> hera:~> dig -x 67.215.66.132

; <<>> DiG 9.7.2-P2 <<>> -x 67.215.66.132
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45490
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 3, ADDITIONAL: 3

;; QUESTION SECTION:
;132.66.215.67.in-addr.arpa.    IN      PTR

;; ANSWER SECTION:
132.66.215.67.in-addr.arpa. 86400 IN    PTR     hit-servfail.opendns.com.
132.66.215.67.in-addr.arpa. 86400 IN    PTR     servfail.guide.opendns.com.

;; AUTHORITY SECTION:
66.215.67.in-addr.arpa. 86400   IN      NS      auth2.opendns.com.
66.215.67.in-addr.arpa. 86400   IN      NS      auth1.opendns.com.
66.215.67.in-addr.arpa. 86400   IN      NS      auth3.opendns.com.
[...]
;; Query time: 366 msec
;; SERVER: 10.0.0.220#53(10.0.0.220)
;; WHEN: Sun Apr  3 12:27:02 2011
;; MSG SIZE  rcvd: 219

Both of the addresses you gave point back to www-files.opendns.com:

m3047 <at> hera:~> dig -x 208.67.216.142
[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 51348
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3
[...]
;; ANSWER SECTION:
142.216.67.208.in-addr.arpa. 86400 IN   PTR     www-files.opendns.com.

;; AUTHORITY SECTION:
216.67.208.in-addr.arpa. 86400  IN      NS      auth2.opendns.com.
216.67.208.in-addr.arpa. 86400  IN      NS      auth1.opendns.com.
216.67.208.in-addr.arpa. 86400  IN      NS      auth3.opendns.com.
[...]

m3047 <at> hera:~> dig -x 204.194.237.142
[...]
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48632
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3
[...]
;; ANSWER SECTION:
142.237.194.204.in-addr.arpa. 86400 IN  PTR     www-files.opendns.com.

;; AUTHORITY SECTION:
237.194.204.in-addr.arpa. 86400 IN      NS      auth1.opendns.com.
237.194.204.in-addr.arpa. 86400 IN      NS      auth3.opendns.com.
237.194.204.in-addr.arpa. 86400 IN      NS      auth2.opendns.com.
[...]

The TTL on the forward (A) RR for www-files.opendns.com appears to be an hour 
(compared to the reverse which is one day). They might have just moved the 
server; or, it might be multi-homed or geo-cast (not to be confused with 
anycast) and there are some routing issues.

It is remotely possible that they (or .com, but I think I'd have heard about 
it) screwed up a key signing... .COM was just signed, and they'd have to be 
bleeding edge amongst ISPs to be running DNSSEC on their caching resolvers... 
or on their own domain.

With some of the stuff I see, I sometimes find it amusing that DNS works at 
all. :-j

For more fun than a barrel of simians trying to recreate Shakespeare (there's 
an RFC for that), I visited servfail.guide.opendns.com and it redirected to 
http://guide.opendns.com/main?url=servfail.guide.opendns.com&servfail=

  "Hmm, servfail.guide.opendns.com isn't loading right now.

  The computers that run servfail.guide.opendns.com are having some
  trouble. Usually this is just a temporary problem, so you might want
  to try again in a few minutes."

I can't remember if this list accepts attachments, so I won't attach a 
screenshot. :-p

--

Fred Morris
an internet plumber working in Tacoma

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Derek Simkowiak | 3 Apr 2011 23:24

Re: OT Strange dns behavior

    I think everything is working normally for you... by which I mean Microsoft Windows is causing your problem. :)

    First:

C:\Users\Tom>nslookup www-files.opendns.com 208.67.222.222
Server:  resolver1.opendns.com
Address:  208.67.222.222

Non-authoritative answer:
Name:    www-files.opendns.com.ftrdhcpuser.net
Address:  67.215.66.132 <========================= !!



    The address that returned here, 67.215.66.132, is the address for "hit-nxdomain.opendns.com", which is the "No Such Domain" web server for OpenDNS.

    When you ask OpenDNS to resolve a non-existent host name, it replies with the fake, not-really-resolved IP address that you see above.  This is how OpenDNS works.  Most OpenDNS customers are using a web browser, and if you make a typo in the domain name (like "googgle.com") it resolves it to the OpenDNS "No Such Domain" server, and shows you a list of search results, with an advertisement at the top.  That is how they make their money, and it is why OpenDNS is free.  Here is an example with a non-existent host called "banana", and note the 67.215.65.132 address that shows up again:

derek <at> derek-laptop:~$ ping -c 1 banana
PING banana.cool-st.com (67.215.65.132) 56(84) bytes of data.
64 bytes from hit-nxdomain.opendns.com (67.215.65.132): icmp_seq=1 ttl=50 time=41.6 ms

--- banana.cool-st.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 41.674/41.674/41.674/0.000 ms
derek <at> derek-laptop:~$

    This behavior is very annoying if you're expecting a "no such host" error.  But it's really useful for businesses because OpenDNS filters out known phishing, adware, porn, virus, and various other liability domains for your average Outlook user.  (And unlike the useless corporate filtering products, OpenDNS's categories are maintained by the community in a Wikipedia-like fashion.)

    In the example above, Microsoft Windows took your requested DNS name, "www-files.opendns.com", and decided that what you really meant was "www-files.opendns.com.YOURDOMAIN".  (Notice that the line above your arrow says "www-files.opendns.com.FTRDHCPUSER.NET", which does not exist, and thus, resolved to hit-nxdomain.opendns.com.)  This "feature" of Windows is supposed to let you do things like "ping www-files" and have that correctly resolve to "www-files.YOURDOMAIN", but alas, LOL <at> Windows.  It's basically a broken version of the "search" line in /etc/resolv.conf.  Switch to Linux, problem solved.

    Second:

C:\Users\rw>nslookup www-files.opendns.com 208.67.222.222
Address:  208.67.222.222

Non-authoritative answer:
Address:  204.194.237.142  <=============================

    In this case, I'm not sure why you get that address.  I do not -- using both Comcast Business Class Internet and T-Mobile "4G" Internet, that host resolves to "208.67.216.142".  But the address you got is still a valid and correct response:

derek <at> derek-laptop:~$ host 204.194.237.142
142.237.194.204.in-addr.arpa domain name pointer www-files.opendns.com.
derek <at> derek-laptop:~$ host 208.67.216.142
142.216.67.208.in-addr.arpa domain name pointer www-files.opendns.com.
derek <at> derek-laptop:~$

    Perhaps the server www-files.opendns.com is multi-homed, having two (or more) IP addresses on different networks.  Perhaps a router someplace decided that the path to the 204.194.237.x subnet was the best route from Frontier.  Or maybe they were doing maintenance and had rotated in the backup server when you ran your test.  Or maybe they are doing something more esoteric, like load balancing with LVS and using it's client-hash based load balancing algorithm... In short, reason unkown.  You can ask OpenDNS why that might happen, but they may not want to tell you.  It's working correctly.


--Derek

On 04/02/2011 11:09 PM, Rich Wilson wrote:
Perhaps those with more knowledge than I can help me understand
the following behavior. It appears that opendns doesn't supply one of
their own addresses correctly. Sorry for the funny prompt (hence OT), 
but the same thing does happen in Linux.

----------------------------------------------------------------------------------------
C:\Users\rw>nslookup www-files.opendns.com 208.67.222.222
Address:  208.67.222.222

Non-authoritative answer:
Address:  204.194.237.142  <=============================


C:\Users\rw>nslookup www-files.opendns.com 8.8.8.8
Address:  8.8.8.8

Non-authoritative answer:
Address:  208.67.216.142 <=============================
--------------------------------------------------------------------

It appears that if I ask for a dns lookup of www-files.opendns.com, I get the wrong
answer from the opendns server. But only some people have this problem. With  
n=3 so far, only frontier.com customers have this problem. The result is that the
opendns.com web site does not display at all, or incorrectly after a long delay.

It gets even stranger with the following result:

------------------------------------------------------------------------------
C:\Users\Tom>nslookup www-files.opendns.com
Server:  Wireless_Broadband_Router.ftrdhcpuser.net
Address:  192.168.1.1

Non-authoritative answer:
Name:    www-files.opendns.com
Address:  208.67.216.142


C:\Users\Tom>nslookup www-files.opendns.com 208.67.222.222
Server:  resolver1.opendns.com
Address:  208.67.222.222

Non-authoritative answer:
Name:    www-files.opendns.com.ftrdhcpuser.net
Address:  67.215.66.132 <========================= !!
--------------------------------------------------------------------------------

The supplied address doesn't even have the same name!

The first result (rw) is frontier DSL, and the second (Tom) frontier FIOS.

I'm curious whether other frontier customers see the same behavior,
and whether all non-frontier customers see correct behavior.

How can this behavior be explained? Who's to blame? opendns? frontier? 
My queries to opendns have met with the "we're perfect, you're doing
something wrong" response.

(If this looks familiar, I asked a similar question on SLL when I knew less.
I'm asking here with the likelihood that there are more frontier customers
present, and perhaps n can be enlarged.)

Rich
--
Rich Wilson
richaw <at> gmail.com

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Rich Wilson | 3 Apr 2011 23:42
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Re: OT Strange dns behavior

The problem I was having has gone away. So I presume that one of their servers
was temporarily not supplying the files needed to display their web pages,
and the problem has been fixed. I still get the 204.x.x.x response on my computer.
And by the way, I did from Linux also.

The following friend does not use opendns or Linux, so I don't know if he would still
be having problems if he tried to configure his sytem to use their DNS servers.

C:\Users\Tom>nslookup www-files.opendns.com 208.67.222.222
Server:  resolver1.opendns.com
Address:  208.67.222.222

Non-authoritative answer:
Name:    www-files.opendns.com.ftrdhcpuser.net
Address:  67.215.66.132 <========================= !!


Thanks for your help.

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richaw <at> gmail.com

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Bri Hatch | 4 Apr 2011 01:12

Re: OT Strange dns behavior

Close to Sun, Apr 3, 2011 at 2:24 PM, Derek Simkowiak
<dereks <at> realloc.net> mentioned:

> When you ask OpenDNS to resolve a non-existent host name, it replies
> with the fake, not-really-resolved IP address that you see above.

...

> This behavior is very annoying if you're expecting a "no such host"
> error.

You say that as if expecting an NXDOMAIN is a bad thing, as if
the DNS RFCs were misguided or something.

>    But it's really useful for businesses because OpenDNS filters out
> known phishing, adware, porn, virus, and various other liability domains for
> your average Outlook user.

This kind of filtering can be done in multiple locations (firewall/proxy,
antivirus, etc) and in some cases is a technological solution to a
non-technical problem.  Don't want employees surfing porn?  You
should have that written in the policy handbook and periodically
check the logs and punish the offenders.

Sorry, but I prefer NXDOMAIN when I type a URL that's wrong.
I certainly don't think it's appropriate for them to hijack
other people's traffic as they have done with Google in the past.
Do they still do it?  Not sure.  But I don't see that as a valid
offering of a DNS provider.

Here are the breakdowns of your DNS setup as I see them:

You want: ultimate control and a 100% accurate Internet experience
  * run your own bind/djbdns/etc server.
  * unless attackers can hijack UDP packets to the roots and all
    other required nameservers, you're probably pretty secure.

You want: fast results and don't care about accuracy
  * use your ISPs domain name server
    * they're closest
    * they probably have a lot of cached records
  * but
    * they may be intercepting non existant domains to monetize via ads
    * they may have bad security, and could be returning results that
      were crafted by attackers to send you to or through their sites,
      re-writing pages or sniffing your passwords.
      Yes, various ISPs have had their DNS servers compromised.

You want: fast results and care about accuracy
  * use Google Public DNS
    * 8.8.8.8, 8.8.4.4
    * doesn't hijack any records, will return NXDOMAIN when you
      typo a domain
    * often faster than your ISPs name servers
    * no known dns security problems to date
  * but
    * doesn't offer phishing protection/content filtering, etc
      * phishing/malware protection most likely already in your browser

You want: fast results and need content filtering/phishing protection
  * use OpenDNS
    * has blocking features, e.g. whitelists, blacklists, etc
    * performs typo squatting to serve you ads
    * possibly intercepts and proxies your traffic to other
      websites
    * excellent security track record
    * you specifically want to be blocked from some things on the
      internet
    * you don't mind that the service has hijacked legitimate third
      party sites like Google in the past, for reasons that many find
      dubious.

If you need the content filtering protections that OpenDNS provides,
then it makes sense to use them.  If not, I don't know why you'd
use a service that provides you a compromised view of the Internet.

> In the example above, Microsoft Windows took your requested DNS name,
> "www-files.opendns.com", and decided that what you really meant was
> "www-files.opendns.com.YOURDOMAIN".   (Notice that the line above your arrow
> says "www-files.opendns.com.FTRDHCPUSER.NET", which does not exist, and
> thus, resolved to hit-nxdomain.opendns.com.)   This "feature" of Windows is
> supposed to let you do things like "ping www-files" and have that correctly
> resolve to "www-files.YOURDOMAIN", but alas, LOL <at> Windows.   It's basically a
> broken version of the "search" line in /etc/resolv.conf.   Switch to Linux,
> problem solved.

This isn't window's fault.  It's caused by using a DNS provider
that hijacks NXDOMAIN.  Don't use OpenDNS and you can use any
operating system you want that supports the DNS standards.

-- 
Bri Hatch, Systems and Security Engineer. http://www.ifokr.org/bri/

Avoid trendy locutions that sound flaky.

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Fred Morris | 4 Apr 2011 04:04

Re: OT Strange dns behavior

On Sunday 03 April 2011 14:24, Derek Simkowiak wrote:
>      The address that returned here, 67.215.66.132, is the address for 
> "hit-nxdomain.opendns.com", which is the "No Such Domain" web server for 
> OpenDNS.

You didn't say how you derived that. They must be doing something clever with 
virtual named hosts, and contexted on the querant's IP, because I got:

> m3047 <at> hera:~> dig -x 67.215.66.132
> 
> ; <<>> DiG 9.7.2-P2 <<>> -x 67.215.66.132
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45490
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 3, ADDITIONAL: 3
> 
> ;; QUESTION SECTION:
> ;132.66.215.67.in-addr.arpa.    IN      PTR
> 
> ;; ANSWER SECTION:
> 132.66.215.67.in-addr.arpa. 86400 IN    PTR     hit-servfail.opendns.com.
> 132.66.215.67.in-addr.arpa. 86400 IN    PTR     servfail.guide.opendns.com.
> 
> ;; AUTHORITY SECTION:
> 66.215.67.in-addr.arpa. 86400   IN      NS      auth2.opendns.com.
> 66.215.67.in-addr.arpa. 86400   IN      NS      auth1.opendns.com.
> 66.215.67.in-addr.arpa. 86400   IN      NS      auth3.opendns.com.
> [...]
> ;; Query time: 366 msec
> ;; SERVER: 10.0.0.220#53(10.0.0.220)
> ;; WHEN: Sun Apr  3 12:27:02 2011
> ;; MSG SIZE  rcvd: 219

Wheee!

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Derek Simkowiak | 4 Apr 2011 22:17

Re: OT Strange dns behavior

> You didn't say how you derived that.   

    It was in the rdns of the "ping banana" example I posted.  Here it is again -- note that host "banana" does not exist, but OpenDNS resolves it to the "hit-nxdomain" rdns name:

derek <at> derek-laptop:~$ ping -c 1 banana
PING banana.cool-st.com (67.215.65.132) 56(84) bytes of data.
64 bytes from hit-nxdomain.opendns.com (67.215.65.132): icmp_seq=1 ttl=50 time=51.5 ms

--- banana.cool-st.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 51.569/51.569/51.569/0.000 ms
derek <at> derek-laptop:~$


    And here it is again, from dig:

derek <at> derek-laptop:~$ dig -x 67.215.65.132

; <<>> DiG 9.7.0-P1 <<>> -x 67.215.65.132
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48161
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;132.65.215.67.in-addr.arpa.    IN    PTR

;; ANSWER SECTION:
132.65.215.67.in-addr.arpa. 80944 IN    PTR    hit-nxdomain.opendns.com.

;; Query time: 60 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Mon Apr  4 13:14:29 2011
;; MSG SIZE  rcvd: 82

derek <at> derek-laptop:~$

    But oddly, when I first ran that "dig" command a few minutes ago, I got the same result you posted below.

    Maybe this is part of their high availability / geo-redundant setup... dunno.

--Derek

On 04/03/2011 07:04 PM, Fred Morris wrote:
On Sunday 03 April 2011 14:24, Derek Simkowiak wrote:
The address that returned here, 67.215.66.132, is the address for "hit-nxdomain.opendns.com", which is the "No Such Domain" web server for OpenDNS.
You didn't say how you derived that. They must be doing something clever with virtual named hosts, and contexted on the querant's IP, because I got:
m3047 <at> hera:~> dig -x 67.215.66.132 ; <<>> DiG 9.7.2-P2 <<>> -x 67.215.66.132 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45490 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 3, ADDITIONAL: 3 ;; QUESTION SECTION: ;132.66.215.67.in-addr.arpa. IN PTR ;; ANSWER SECTION: 132.66.215.67.in-addr.arpa. 86400 IN PTR hit-servfail.opendns.com. 132.66.215.67.in-addr.arpa. 86400 IN PTR servfail.guide.opendns.com. ;; AUTHORITY SECTION: 66.215.67.in-addr.arpa. 86400 IN NS auth2.opendns.com. 66.215.67.in-addr.arpa. 86400 IN NS auth1.opendns.com. 66.215.67.in-addr.arpa. 86400 IN NS auth3.opendns.com. [...] ;; Query time: 366 msec ;; SERVER: 10.0.0.220#53(10.0.0.220) ;; WHEN: Sun Apr 3 12:27:02 2011 ;; MSG SIZE rcvd: 219
Wheee! -- Fred Morris

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Derek Simkowiak | 5 Apr 2011 00:25

Re: OT Strange dns behavior

> This kind of filtering can be done in multiple locations (firewall/proxy, antivirus, etc)

    The primary reason I prefer OpenDNS is the human community who maintains the categories.  I've been subjected to corporate, authoritarian filters and they are ineffective and inaccurate.  Plus, I have moral objections against the corporate and religious bias that appears in those products:

http://www.csriu.org/onlinedocs/documents/religious2.html

    Do you know of an alternate site-categorization system that is maintained by a peer-reviewed community?  (And free?)  I'd be very interested...


> Don't want employees surfing porn? You should have that written in the policy handbook and periodically check the logs and punish the offenders.

    I have a funny story about that.

    I was at a client's office, working on a Samba error in the logs.  I hopped onto one of their empty workstations and googled the error message -- it was some random, esoteric, highly technical thing, something like "protocol.c: error 53".  I do this type of thing all the time, so within a few seconds I had several Firefox tabs open with search results in them.

      One of the tabs was a mailing list web-mirror of samba-users.  The poster had the exact same symptoms as me, so I was sitting there, intently focused on the logs he had posted.  I'm sitting there, staring intently at the screen... and then one of the employees comes up behind me and says "What the __HECK__ are you looking at?!"

    I was a little confused, so I gave him a weird sneer and said "I'm just looking up this error message..." -- and then I saw it. 

    The mailing list mirror was not a simple Mhonarc or Mailman web archive.  It was one of those annoying mailing list mirrors that are basically parked domains.  They mirror Open Source mailing lists, but also include a bunch of large, flashy ads.  I've trained myself to skip ads altogether, especially when hunting down tech info, so I saw nothing but the post.  But right there on the screen -- in an embarrassingly large pixel size -- was a totally NSFW ad for a porn site (or something similar).  Skimpy lingerie, suggestive pose, ...

    Just _try_ talking yourself out of that situation.  It doesn't work.

    (I wonder what my wife would say... is it worse that I had a NSFW girl on the screen... or that I skipped over her completely in favor of some Samba logs? lol )

    Anywayz, for my clients at least, porn isn't really the issue.  (Open cubicles + porn = totally impractical.)  It's the clueless Outlook users who'll click on any infected PDF link that lands in their Inbox.  OpenDNS helps by filtering many of them, and also by (optionally) maintaining a log of which IP addresses tried to resolve known virus domains.


>> This behavior is very annoying if you're expecting a "no such host" error.

> You say that as if expecting an NXDOMAIN is a bad thing, as if the DNS RFCs were misguided or something.

    Not at all... it's the one thing I don't like about using the free version of OpenDNS. 

    OpenDNS does have a paid version with no advertisements, so if I coughed up the $5 per year I wouldn't need to tolerate it.


> > In the example above, Microsoft Windows took your requested DNS name, "www-files.opendns.com", and decided that what you really meant was "www-files.opendns.com.YOURDOMAIN".

> This isn't window's fault.

    Eh?

    Responding to a non-existent host is OpenDNS (free version), agreed, and yes it's annoying, agreed, see above.  But appending YOURDOMAIN to a hostname like "www-files.opendns.com" at the command line?  Is that okay?  I'm just glad Linux doesn't do that.  (Windows doesn't always do this, but I've have had to fight this problem for clients, and it's a major PITA.)


> [OpenDNS] possibly intercepts and proxies your traffic ... hijacked legitimate third party sites like Google in the past, for reasons that many find dubious... provides you a compromised view of the Internet.

    Ye gods...  "Intercepts"?  "Hijacked"?  "Reasons that many find dubious"?  "Compromised"?  Puh-leeze.  OpenDNS is an Open-Source friendly company, founded and run by engineers, supported by a vibrant community, and it has one of the better privacy policies on the web.  They're not perfect, but they're certainly not the demon-corporation that you make them out to be.

    The "hijack" issue to which you refer is not "legitimate third party sites like Google"... it was exactly Google, and only Google.  They provide a full explanation of what they do, and why they do it, here:

http://blog.opendns.com/2007/05/22/google-turns-the-page/

    And an independent assesment of the situation:

http://searchengineland.com/google-dells-revenue-generating-url-error-pages-drawing-fire-11283

    I don't like what OpenDNS does with Google, but I also don't like what Google does with Dell.  In the end, Google is my homepage, OpenDNS is my DNS, and my Dell laptop runs just fine.

    OpenDNS has never, to my knowledge, done anything that could rightfully be called "intercepting" or "compromising".  They do some hackery with the DNS protocol, yes, but their web site explains exactly what they do, why they do it, and how it works.  You are free to not use them... but I, for one, welcome our new DNS overlords.


--Derek


On 04/03/2011 04:12 PM, Bri Hatch wrote:
Close to Sun, Apr 3, 2011 at 2:24 PM, Derek Simkowiak <dereks <at> realloc.net> mentioned:
When you ask OpenDNS to resolve a non-existent host name, it replies with the fake, not-really-resolved IP address that you see above.
...
This behavior is very annoying if you're expecting a "no such host" error.
You say that as if expecting an NXDOMAIN is a bad thing, as if the DNS RFCs were misguided or something.
But it's really useful for businesses because OpenDNS filters out known phishing, adware, porn, virus, and various other liability domains for your average Outlook user.
This kind of filtering can be done in multiple locations (firewall/proxy, antivirus, etc) and in some cases is a technological solution to a non-technical problem. Don't want employees surfing porn? You should have that written in the policy handbook and periodically check the logs and punish the offenders. Sorry, but I prefer NXDOMAIN when I type a URL that's wrong. I certainly don't think it's appropriate for them to hijack other people's traffic as they have done with Google in the past. Do they still do it? Not sure. But I don't see that as a valid offering of a DNS provider. Here are the breakdowns of your DNS setup as I see them: You want: ultimate control and a 100% accurate Internet experience * run your own bind/djbdns/etc server. * unless attackers can hijack UDP packets to the roots and all other required nameservers, you're probably pretty secure. You want: fast results and don't care about accuracy * use your ISPs domain name server * they're closest * they probably have a lot of cached records * but * they may be intercepting non existant domains to monetize via ads * they may have bad security, and could be returning results that were crafted by attackers to send you to or through their sites, re-writing pages or sniffing your passwords. Yes, various ISPs have had their DNS servers compromised. You want: fast results and care about accuracy * use Google Public DNS * 8.8.8.8, 8.8.4.4 * doesn't hijack any records, will return NXDOMAIN when you typo a domain * often faster than your ISPs name servers * no known dns security problems to date * but * doesn't offer phishing protection/content filtering, etc * phishing/malware protection most likely already in your browser You want: fast results and need content filtering/phishing protection * use OpenDNS * has blocking features, e.g. whitelists, blacklists, etc * performs typo squatting to serve you ads * possibly intercepts and proxies your traffic to other websites * excellent security track record * you specifically want to be blocked from some things on the internet * you don't mind that the service has hijacked legitimate third party sites like Google in the past, for reasons that many find dubious. If you need the content filtering protections that OpenDNS provides, then it makes sense to use them. If not, I don't know why you'd use a service that provides you a compromised view of the Internet.
In the example above, Microsoft Windows took your requested DNS name, "www-files.opendns.com", and decided that what you really meant was "www-files.opendns.com.YOURDOMAIN". (Notice that the line above your arrow says "www-files.opendns.com.FTRDHCPUSER.NET", which does not exist, and thus, resolved to hit-nxdomain.opendns.com.) This "feature" of Windows is supposed to let you do things like "ping www-files" and have that correctly resolve to "www-files.YOURDOMAIN", but alas, LOL <at> Windows. It's basically a broken version of the "search" line in /etc/resolv.conf. Switch to Linux, problem solved.
This isn't window's fault. It's caused by using a DNS provider that hijacks NXDOMAIN. Don't use OpenDNS and you can use any operating system you want that supports the DNS standards.

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Ron Parker | 9 Apr 2011 01:40
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can pay for help with virus

short message
virus attack
need help reinstalling ubuntu 10.10 desktop on two hp pavillion laptop
my cd's will not give a clean reload
I'll be at the meeting tomorrow




 
regards to all,

Grandpa, Dad, Uncle, Ron as applicable
"If you don't have a dream, how are you going to have a dream come true?" James Michener - South Pacific


From: William Hale <altsalt <at> gmail.com>
To: GSLUG <gslug-announce <at> gslug.org>; GSLUG <gslug-general <at> gslug.org>
Sent: Thu, March 24, 2011 10:08:18 AM
Subject: [Gslug-general] Next Meeting: April 9, 2011

Hello Everyone!

The next GSLUG meeting will be held Saturday, April 9th from 12 till 4
at the Google offices in Fremont.

More information can be found at:
http://www.gslug.org/wiki/index.php/Meeting_2011-04-09

This month's topic is Linux Graphics. Talks will be focused on
anything graphics related on Linux platforms.

Please RSVP if you plan on attending and sign up for a talk if there
is something you'd like to share with the group.

We'll be ordering pizza at the start of the meeting for those
interested (plan on $5 to cover costs).

We are still looking for someone to run the Trivia, please reply if
you are interested.

Also, we are running low on door prizes.  So if you have anything to
donate, please bring it along.

Hope to see everyone there!

--
William

Utinam me logica falsa tuam philosophiam totam suffodiant.

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William Hale | 9 Apr 2011 10:24
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Tomorrow's Meeting

Hello Everyone,

It's that time of the month, tomorrow a GSLUG meeting will be held at
Google Fremont. More information can be found at:
http://www.gslug.org/wiki/index.php/Meeting_2011-04-09

As of right now we have the room from 12-2pm. Due to the shortened
amount of time, we will not be ordering pizza. However, there will
probably be a group going out for food after the meeting at a nearby
location.

I hope to see everyone there!

--
William

Utinam me logica falsa tuam philosophiam totam suffodiant.

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