Name resolution via the Technicolor TG582n

[#1]

I have recently migrated to Plus.net and aquired a Technicolor TG582n in the process. The name servers are correctly set as 212.159.13.49 and 212.159.13.50, however, the router then insists on adding itself as a primary NS, I guess to act as a caching DNS proxy. Hence my DNS settings look like:

   DNS Servers . . . . . . . . . . . : 192.168.1.254
                                       212.159.13.49
                                       212.159.13.50

Everything works until you try a CLI nslookup or dig as then you get:

C:\Users\User>nslookup
DNS request timed out.
    timeout was 2 seconds.
Default Server:  UnKnown
Address:  192.168.1.254
> www.google.co.uk
Server:  UnKnown
Address:  192.168.1.254
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out
> server 212.159.13.49
DNS request timed out.
    timeout was 2 seconds.
Default Server:  [212.159.13.49]
Address:  212.159.13.49
> www.google.co.uk
Server:  [212.159.13.49]
Address:  212.159.13.49
Non-authoritative answer:
Name:    www.google.co.uk
Addresses:  2a00:1450:400c:c05::5e
          74.125.132.94
> server 192.168.1.254
Default Server:  [192.168.1.254]
Address:  192.168.1.254
> www.google.co.uk
Server:  [192.168.1.254]
Address:  192.168.1.254
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to [192.168.1.254] timed-out
>

This shows that a name resolution via the default and first NS which the router insists on adding to the DHCP response only fails. Only when you set the resolving server to be one of the Plus.net servers does the resolution work. This then suggests that every NS query is going through this failure loop, with the primary NS returning nothing and so the secondary having to be used.
So my question is, how do I stop the Technicolor adding itself as the first NS or how do I get it to forward the request properly and so resolve names?

[#2]

Interestingly, telnetting to the router directly I get the following:

{admin}=>dns server route list
DNS Server Entries:
  DNS Server     Source                Label              Metric Intf         State  Domain
D 212.159.6.10                                            10     Internet      UP      *
D 212.159.6.9                                             10     Internet      UP      *

Which suggests the DNS settings you provide to the router are only one it passes back to DHCP clients and not ones it uses itself...

[#3]

Oh well, answering my own question, but in case it helps others...

• Tenet to the router


• Type: dns server config state=disabled


• Type: saveall


• Back on your workstation, type: ipconfig /renew


• Type: ipconfig /all - and you'll see the router as primary NS will have gone


• Now do an nslookup and find that it works!

With thanks to: http://support.zen.co.uk/kb/Knowledgebase/Broadband-Securing-your-Technicolor-TG582n-against-Open-Re...
Another useful article on altering DNS setting within the Technolcolor at: http://www.petecooper.org/tutorials/changing-dns-servers-on-a-technicolor-tg582n-fttc ; This is primarily about moving to OpenDNS or Google DNS  which is a different issue and in fact has some disadvantages for any content (like streaming media) that you get, as using a DNS remote to your ISP's network can result in you getting a remote content server rather than one local to your ISP's network, but this is another topic 🙂
Example session:

Username : admin
Password : ***********
------------------------------------------------------------------------
                             ______  Technicolor TG582n
                         ___/_____/\
                        /         /\\  8.4.4.J.BV
                  _____/__       /  \\
                _/       /\_____/___ \  Copyright (c) 1999-2011, Technicolor
               //       /  \       /\ \
       _______//_______/    \     / _\/______
      /      / \       \    /    / /        /\
   __/      /   \       \  /    / /        / _\__
  / /      /     \_______\/    / /        / /   /\
 /_/______/___________________/ /________/ /___/  \
 \ \      \    ___________    \ \        \ \   \  /
  \_\      \  /          /\    \ \        \ \___\/
     \      \/          /  \    \ \        \  /
      \_____/          /    \    \ \________\/
           /__________/      \    \  /
           \   _____  \      /_____\/
            \ /    /\  \    /___\/
             /____/  \  \  /
             \    \  /___\/
              \____\/
------------------------------------------------------------------------
{admin}=>dns server route list
DNS Server Entries:
  DNS Server     Source                Label              Metric Intf         State  Domain
D 212.159.6.10                                            10     Internet      UP      *
D 212.159.6.9                                             10     Internet      UP      *
{admin}=>dns server config state=disabled
{admin}=>saveall
{admin}=>

And then on your workstation:

C:\Users\User>ipconfig /renew
Windows IP Configuration
...[lots of guff]

C:\Users\User>ipconfig /all
Windows IP Configuration
...
   DNS Servers . . . . . . . . . . . : 212.159.13.49
                                       212.159.13.50
...
C:\Users\User>nslookup
Default Server:  cdns01.plus.net
Address:  212.159.13.49
> www.google.co.uk
Server:  cdns01.plus.net
Address:  212.159.13.49
Non-authoritative answer:
Name:    www.google.co.uk
Addresses:  2a00:1450:400c:c03::5e
          74.125.132.94
>

[#4]

The router can be configured at least two different ways to issue the DNS server IP address via DHCP
Method 1) -- default
Is to issue the routers gateway IP (192.168.1.254) as the DNS resolver via DHCP.
This is used as a relay, it doesn't cache any results, and forwards lookup to the specified IP addresses show by the cli command "dns server route list".
Method 2)
Is to disable the above and issue the actual DNS server IP addresses via DHCP.
The cli commands for the two methods can be found here:
http://npr.me.uk/changedns.html
From what you say, it sounds as though you don't have ether method configured correctly.

Quote

"The name servers are correctly set as 212.159.13.49 and 212.159.13.50"

How did you configure this?

[#5]

• Login to the router UI


• Select: Home Network


• Select: Interfaces


• Click on: Local Network


• Click on: Configure (top right)


• Uncheck: 'Use DHCP Server' and click: Apply


• Click on: Configure (top right) again as the page refreshes in 'Overview' mode


• Under 'DHCP Pools' click on the Edit button for 'LAN_private'


• Enter all your DHCP info including primary and secondary DNS


• Click: Apply


• Click on: Configure (top right) again as the page refreshes in 'Overview' mode


• Check the 'Use DHCP Server' checkbox and click: Apply

...and you should be there

[#6]

@npr: I'd be surprised if th erouter doesn't cache DNS results. There's no point in using it as a proxy if it doesn't cache and it's usual for a router to do this so as to provide local network resolution...only in the case of the Technicolor an nslookup with this 'installed' simply fails.
So in my setup I had provided the suggested Plus.net DNS in the DHCP settngs and the router then added itself on top of the primary and secondary names defined. Disabling name resoluton by the router solved this and seems a better solution.

[#7]

Quote from: iain

@npr: I'd be surprised if th erouter doesn't cache DNS results. There's no point in using it as a proxy if it doesn't cache and it's usual for a router to do this so as to provide local network resolution...only in the case of the Technicolor an nslookup with this 'installed' simply fails.

I've never seen a router which caches dns.
Try this dig command and note the "Query time".
If the name was cached by the router the query time would be  0 ms (or close to 0) not 31 ms.
Run the command a couple of times prove things.

Quote

dig bbc.co.uk @192.168.1.254 ; <<>> DiG 9.8.6-P1 <<>> bbc.co.uk @192.168.1.254 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36783 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;bbc.co.uk.                    IN      A ;; ANSWER SECTION: bbc.co.uk.              300    IN      A      212.58.253.67 bbc.co.uk.              300    IN      A      212.58.251.195 ;; Query time: 31 msec ;; SERVER: 192.168.1.254#53(192.168.1.254) ;; WHEN: Sun Dec 01 21:04:02 GMT Standard Time 2013 ;; MSG SIZE  rcvd: 59

As for your original problem, it looks like the GUI makes a mess of things -- best to use the telnet methods.

[#8]

An example that the TG582n does not cache anything is in the ns_bench test below which shows some popular Dns Servers, if you look at the last 2 results 192.168.0.254  which is the Router, and 192.168.0.15 my local cache/forwarder.

Nameserver              Response Time (ms)                        min/avg/max/stdev/retries
 
212.159.6.9             17.79/18.39/19.38/0.55/0
212.159.6.10            18.21/18.51/18.88/0.25/0
212.159.13.49           18.36/18.59/18.90/0.24/0
212.159.13.50           19.45/19.80/20.40/0.35/0
208.67.222.222          18.03/18.91/19.79/0.57/0
208.67.222.220          18.54/18.93/19.28/0.28/0
208.67.222.123          17.66/18.21/18.86/0.53/0
208.67.220.123          17.50/18.09/18.42/0.34/0
8.8.8.8                 23.06/23.50/23.83/0.26/0
8.8.4.4                 23.39/23.42/23.45/0.02/0
4.2.2.1                 17.30/18.32/19.34/0.74/0
4.2.2.6                 18.57/19.01/19.37/0.26/0
192.168.0.254           21.05/22.26/22.89/0.63/0
192.168.0.15            0.57/0.60/0.69/0.04/0

As you can see, the cache is taking just over half a second. As for the dns/forwarder "Router" you need to use the cli for that.

[#9]

Not a lot of point in the router inserting itself as primary DNS then if it doesn't cache the results. Usually a forwarding DNS like this would cache results so it's a surprise that it isn't, although I quite take your point about timings although you'd need to request several times as on first request the router will indeed need to go out to get results.

[#10]

Quote from: iain

Not a lot of point in the router inserting itself as primary DNS then if it doesn't cache the results.

The point is, so you can resolve hosts on the local network.
If you want a caching resolver on your network try running Unbound on a Raspberry Pi.
http://npr.me.uk/pidns.html

[#11]

You miss my point.
The router adds itself as the primary DNS pushing the DHCP configured prinary and secondary NA down the list. If the router then doesn't cache any retreived results, what is the point of inserting itself as primary? Why ask box a if it *always* has to ask box b? The router might as well pass on box b (and c) as primary and secondary. The only benefit to quoting it as primary is that is caches a resolution for one client and so can provide the answer to a second. If it never caches anything then there is no benefit in it placing itself anywhere in the DNS set-up, much less than as primary.
Any why with it as primary does an nslookup via it fail? It shoudl forward the request and resolve, but on my box it only ever failed. Maybe using the Plusnet box was just a big mistake and I should go back to my Cisco!

[#12]

The main reason is for dns lookup for the local domain (.lan).
However I don't get the same problems as you.

hairybiker@Duo:~$ nslookup
> google.co.uk
Server:		127.0.1.1
Address:	127.0.1.1#53
Non-authoritative answer:
Name:	google.co.uk
Address: 173.194.41.159
Name:	google.co.uk
Address: 173.194.41.152
Name:	google.co.uk
Address: 173.194.41.151
> servers
Server:		127.0.1.1
Address:	127.0.1.1#53
** server can't find servers: NXDOMAIN
> server 192.168.1.254
Default server: 192.168.1.254
Address: 192.168.1.254#53
> google.co.uk
Server:		192.168.1.254
Address:	192.168.1.254#53
Non-authoritative answer:
Name:	google.co.uk
Address: 173.194.41.159
Name:	google.co.uk
Address: 173.194.41.152
Name:	google.co.uk
Address: 173.194.41.151
> 

On my box 127.0.0.1 is set by default but it loops to the router anyway. However I am not using the 582 as I found it useless on the local domain, I have the newer one that is being tested on fibre.

[#13]

I see some intresting results. I've added my 2 pence worth.
TG582n with extras'
$ nslookup
> google.co.uk
Server: 192.168.0.15
Address: 192.168.0.15#53
Non-authoritative answer:
Name: google.co.uk
Address: 173.194.34.120
Name: google.co.uk
Address: 173.194.34.127
Name: google.co.uk
Address: 173.194.34.119
> servers
Server: 192.168.0.15
Address: 192.168.0.15#53
Non-authoritative answer:
Name: servers
Address: 67.215.65.132
> server 192.168.0.254
Default server: 192.168.0.254
Address: 192.168.0.254#53
> google.co.uk
Server: 192.168.0.254
Address: 192.168.0.254#53
Non-authoritative answer:
Name: google.co.uk
Address: 173.194.34.120
Name: google.co.uk
Address: 173.194.34.127
Name: google.co.uk
Address: 173.194.34.119
> 67.215.65.132                                                           
Server: 192.168.0.15
Address: 192.168.0.15#53
Non-authoritative answer:
132.65.215.67.in-addr.arpa name = hit-nxdomain.opendns.com.
Authoritative answers can be found from:
> server 127.0.0.1
Default server: 127.0.0.1
Address: 127.0.0.1#53
> google.co.uk
;; connection timed out; no servers could be reached
> server 127.0.1.1
Default server: 127.0.1.1
Address: 127.0.1.1#53
> google.co.uk
;; connection timed out; no servers could be reached

I use opendns of course on this connection, via both routes, with port 53 blocked. So the route is forced for this connection.
@Hairy McBiker I thought Mint Distros now used Dnsmasq as standard for cache like 12.04 >> ?

[main]
plugins=ifupdown,keyfile,ofono
#dns=dnsmasq
no-auto-default=22:33:0D:F5:08:44,
[ifupdown]
managed=false

[#14]

Nope not using dnsmasq:

hairybiker@Duo:~$ apt show dnsmasq
Package: dnsmasq
State: not installed
Version: 2.66-4ubuntu1
Priority: optional

[#15]

Ok, i just removed the # from my  NetworkManager.conf  to re-enable what i dissabled from a fresh install of mint-mate16. I've posted a snapshot of before and after a reset with  "restart network-manager"
What is the dnsmasq reference doing there ? sudo watch nestat -antup mind U that was mint 16RC i got.

Edit: Add new results from enabled test
nslookup
> server 127.0.1.1
Default server: 127.0.1.1
Address: 127.0.1.1#53
> google.co.uk
Server: 127.0.1.1
Address: 127.0.1.1#53
Non-authoritative answer:
Name: google.co.uk
Address: 173.194.34.127
Name: google.co.uk
Address: 173.194.34.119
Name: google.co.uk
Address: 173.194.34.120