Problems with DNS and my U-verse VDSL connection.

Problems with DNS and my U-verse VDSL connection.

Post by ceed » Fri, 24 Dec 2010 22:46:28



Hi,

I recently got an AT&T U-verse (VDSL) connection at home (I could not  
resist 24 mbps down!). When I connect to the 2Wire 3600 HGV modem/router  
(DHCP) DNS is set to 192.168.1.254 in Network Manager which is the routers  
own IP address and not the DNS server address(es) the modem uses which is  
(read from the modem/routers config UI):

Primary DNS 68.94.156.1
Secondary DNS 68.94.157.1

This doesn't cause problems for web browsing and such, but it breaks apt  
with the following error message when I for instance run sudo apt-get  
update

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dis...ck/Release.gpg  
Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No  
address associated with hostname).

Looks like apt can't "see through" this setup, but I can ping the repos  
(like archive.ubuntu.com) just fine.

The only way around this problem is to set DNS manually in Network Manager  
(using Google, OpenDNS or AT&T's own) for the wireless connection I am  
using. When I do this apt works fine and I can update without errors.  
There's no way to set other DNS servers in the modem/router itself. I  
suspect that has to do with this modem/router being used for VOIP and TV  
services as well.

I'm no network guru so I was wondering why DNS is set to the router/modems  
own IP and not to the DNS servers actually used? Is this a modem/router  
problem or is it Network Manager setting it up wrong? Since I do not have  
any Windows machines around I can not check if the same things happens  
there.

I'm running latest Ubuntu/Mint.

--
//ceed

 
 
 

Problems with DNS and my U-verse VDSL connection.

Post by Bit Twiste » Fri, 24 Dec 2010 23:43:08



> Hi,

> I recently got an AT&T U-verse (VDSL) connection at home (I could not  
> resist 24 mbps down!). When I connect to the 2Wire 3600 HGV modem/router  
> (DHCP) DNS is set to 192.168.1.254 in Network Manager which is the routers  
> own IP address and not the DNS server address(es) the modem uses which is  
> (read from the modem/routers config UI):
> I'm no network guru so I was wondering why DNS is set to the router/modems  
> own IP and not to the DNS servers actually used?

Sounding pretty normal to me. That allows the router's dns values to
be updated without any of the units having to be notified of the change.

Quote:> This doesn't cause problems for web browsing and such, but it breaks apt  
> with the following error message when I for instance run sudo apt-get  
> update

> W: Failed to fetch http://archive.ubuntu.com/ubuntu/dis...ck/Release.gpg  
> Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No  
> address associated with hostname).

> Looks like apt can't "see through" this setup, but I can ping the repos  
> (like archive.ubuntu.com) just fine.

> The only way around this problem is to set DNS manually in Network Manager  
> (using Google, OpenDNS or AT&T's own) for the wireless connection I am  
> using. When I do this apt works fine and I can update without errors.  
> There's no way to set other DNS servers in the modem/router itself. I  
> suspect that has to do with this modem/router being used for VOIP and TV  
> services as well.

Have you been able to modify anything in the router. Check out this link

AT&T Blocks Linux Configuration
http://linuxlock.blogspot.com/2010/12/at-blocks-linux-configuration.html

With routers being cracked and malicious DNS values inserted, I would
set all pcs to known DNS values.

Quote:> Is this a modem/router problem or is it Network Manager setting it up wrong?

If you are able to surf the Internet and ping other sites, then your
network connection is setup correctly.

As to the problem being a modem problem or not, I will guess it is not
the modem's problem.

ISPs are starting to block sites they perceive as delivering malware.
Maybe the ATT internal network saw a download attempt, and caused the problem.
ISP are trying to cache files locally to reduce their internet load.

You showed you could download when using public servers. That proves
the router allows connections to your repository.

Your ping proved router's dns managed to resolve repository's ip.
I would say the problem is somehow related to AT&T internal network.

I have see some weird stuff before. I could not get to google.com.
Change dns servers, it would work. Back to router's values it would be
broke. Everywhere else I checked, worked, only google was broke.

Worked the problem with ISP's high level Tech Support for about 15
minutes. Me restarting pc, resetting modem, Power off/on modem,...

He gave up and forced a modem flush/reset from his end, I restarted my
network. Result, modem had same dns values, but was now on a different
subnet, and ping to google.com worked.