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I'm trying to connect to a website:


i can ping the address:

C:\Users\Ian>ping /6 superuser.com.sixxs.org

Pinging ipv6.nginx.sixxs.net [2001:838:2:1::30:67] with 32 bytes of data:
Reply from 2001:838:2:1::30:67: time=257ms
Reply from 2001:838:2:1::30:67: time=176ms
Reply from 2001:838:2:1::30:67: time=161ms
Reply from 2001:838:2:1::30:67: time=164ms

Ping statistics for 2001:838:2:1::30:67:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 161ms, Maximum = 257ms, Average = 189ms

But neither ping:

C:\Users\Ian>ping supersuer.com.sixxs.org
Ping request could not find host supersuer.com.sixxs.org.
  Please check the name and try again.

But i cannot browse to it (in Chrome or ie):

enter image description here

nor can i telnet to it

C:\Users\Ian>telnet superuser.com.sixxs.org 80
Connecting To superuser.com.sixxs.org...Could not open connection to the host,
  on port 80: Connect failed

But nslookup resolves the name fine, with an authority record and everything!

First we flush the dns, just in case someone wants to suggest it is due to dns caching:

C:\Users\Ian>ipconfig /flushdns

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.

And now back to the lookup:

C:\Users\Ian>nslookup superuser.com.sixxs.org
Server:  solo.avatopia.com

Non-authoritative answer:
Name:    ipv6.nginx.sixxs.net
Addresses:  2001:838:2:1:2a0:24ff:feab:3b53
Aliases:  superuser.com.sixxs.org

All those addresses work:

  • I can ping them
  • I can telnet to port 80 on them
  • I can browse in Chrome (e.g. http://[2001:838:2:1::30:67]) to them

The name even resolves when I manually call the Windows API function GetAddrInfo.

Why how can I diagnose what ping, telnet, Chrome and Internet Explorer are doing wrong?

Note: Wireshark is of now help because the dns server (solo.avatopia.com) is on the other side of an encrypted vpn link; and WireShark refuses to decrypt encrypted vpn traffic.

share|improve this question
Your ping example has a typo. –  Harry Johnston May 28 '12 at 2:58
What happens if you try to ping, telnet, or browse to the canonical name ipv6.nginx.sixxs.net? –  Harry Johnston May 28 '12 at 2:59
@HarryJohnston Where's the ping typo? i don't see it... –  Ian Boyd May 28 '12 at 13:25
@HarryJohnston Ohhhh, ping needs the /6 parameter; it doesn't understand that if it only could resolve an ipv6 address it needs to send an IPv6 ICMP packet. –  Ian Boyd May 28 '12 at 14:43
silly question, but is the web server itself set up to work on ipv6? does it work on ipv4 or other known ipv6 capable systems? Did you try connecting to the ipv6 equivilent of localhost? –  Journeyman Geek May 28 '12 at 15:12

4 Answers 4

up vote 2 down vote accepted

DNS resolution does not automatically mean HTTP reachability; in your case, that is in fact part of the problem.

sixxs.org answers all DNS queries with a CNAME to ipv6.nginx.sixxs.net. As an example, iamugly obviously couldn't be a real site, since there is no top-level domain.

[mpenning@Bucksnort ~]$ dig +short iamugly.sixxs.org
[mpenning@Bucksnort ~]$ dig +short google.com.sixxs.org
[mpenning@Bucksnort ~]$ dig google.com.sixxs.org

; <<>> DiG 9.7.3 <<>> google.com.sixxs.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22229
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0

;google.com.sixxs.org.          IN      A

google.com.sixxs.org.   3553    IN      CNAME   ipv6.nginx.sixxs.net.

sixxs.net.              3316    IN      SOA     ns.paphosting.net. hostmaster.sixxs.net. 2012010601 86400 7200 1209600 86400

;; Query time: 0 msec
;; WHEN: Mon May 28 15:39:58 2012
;; MSG SIZE  rcvd: 133

[mpenning@Bucksnort ~]$

ipv6.nginx.sixxs.net is just an HTTP proxy that forwards traffic, so as long as their proxy is up, it is ping-able and you can telnet to it...

[mpenning@Bucksnort ~]$ telnet superuser.com.sixxs.org 80
Trying 2620:0:6b0:a:250:56ff:fe99:78f7...
Connected to ipv6.nginx.sixxs.net.
Escape character is '^]'.
telnet> quit
Connection closed.
[mpenning@Bucksnort ~]$

After you go to superuser.com.sixxs.org, sixxs.net redirects you through ipv6gate.sixxs.net and they rewrite Super User's html content send all links on the page through foo.sixxs.org.

enter image description here

Something is preventing you from going through sixxs.org, and it probably comes from a vpn server, firewall or transparent http proxy elsewhere in your path.

share|improve this answer

Here is my guess about what is going.

(I was originally going to post this as a comment, but its too long, so I will post it as an answer and leave it up to yourself and/or others to decide if it is correct.)

I think this isp have their nameservers configured to reply to every subdomain.

I tried a random GUID and yes 0937c1fa-15dc-4a3a-837c-b9ada0953a7e.sixxs.org resolves (and to the same ip addresses as superuser.com.sixxs.org)

This means all traffic to 0937c1fa-15dc-4a3a-837c-b9ada0953a7e.sixxs.org will be sent to them. When it gets to them, they are probably examining the http host header to determine how to handle it. In the case of 0937c1fa-15dc-4a3a-837c-b9ada0953a7e.sixxs.org, I would suspect they would simply ignore the request as they are unlikely to know what to do with it.

In the case of superuser.com.sixxs.org, you would think that they should be redirecting this to superuser.com which but this does not appear to work.

I don't think it is possible for anyone outside their setup to know for sure why this does not work, but it could be because they have some internal mapping wrong and it is sending to the wrong destination.

Another possibility is that they may not be providing this service to everyone and it is possible that if a non-subscriber attempts to use this address, it will simply ignore the request.

Bottom line is, I'm not really sure whether telnet, Chrome and Internet Explorer are actually doing anything wrong and I would suggest checking with sixxs.net before assuming there is anything wrong with your setup.

share|improve this answer

I had a simliar issue, here's what I tried.

  1. It could be related to Winsock's LSP, try LSP fix to find out error causing stuff.
  2. Reset Internet Protocol (TCP/IP)
  3. Run sfc /scannow to fix any problems that might arise due to corrupted files.
  4. Reset WinSock netsh winsock reset
    5.Though totally unrelated try resetting your Branch Cache netsh branchcache reset
    6.Reset IPv6 configuration netsh int ipv6 reset
    7.Try Removing and reinstalling your network adapter from the Device Manager
share|improve this answer

I'm not sure if you are only having trouble with the one site, or if it is all websites you cannot connect to (and are using a different pc to post this), but if you're getting DNS errors in your browsers for every site and you still have connectivity and you can ping stuff, give these few commands a try. It's not always one of these, but I have literally never seen all of them not work for your problem.

netsh winsock reset catalog

netsh int ipv4 reset reset.log

netsh int ipv6 reset reset.log

ipconfig /release

ipconfig /flushdns

ipconfig /renew

ipconfig /registerdns
share|improve this answer

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