[wellylug] Netgear DG834G and DNS problem

[Colin Templeman]

Hello Wellyluggers,

Please forgive the size of this posting, but I thought I would submit my 
findings with regard to my new Netgear DG834G router in the hope it might help 
someone else out there that may be experiencing the same problems with DNS when 
using Linux as I have recently had.

For the record, the DG834G is a wireless ADSL modem/router with SPI firewall 
which had attracted plenty of praise when I was googling for info on it.  I also 
discovered that it runs linux natively! [compulsive twiddlers ;) please see 
http://www.suburbia.com.au/~dan/]


Background:
I have had a weird problem for the last week with really slow DNS resolution 
when using Ubuntu Linux.  There was no problem when using Windows XP.  This 
problem manifested last weekend when I i) apt-got the latest Ubuntu fixes and 
ii) installed a DG834G.

I first noticed this problem when entering a query in the google bar of Firefox. 
  The submission would take ages (like 20-30s plus) to resolve - most of that 
time apparently trying to resolve google itself.  At first, I thought it was a 
browser specific issue, but pinging various national and international servers 
would result in either timeouts or a huge latency.

There were plenty of hits when googling, most of them pointing to DNS issues 
with Firefox and/or Ubuntu.  Armed with this info, I tried the following 
suggestions:


Actions tried:

1.) disabled using IPv6 in Firefox (about:config).  This had no effect 
(consistent with a 'more than just Firefox issue')

2.) explicitly setting dns servers to my ISP's instead of defaulting to the ADSL 
router itself.  I did this in /etc/dhcp3/dhclient.conf (and associated script) 
and then checked the entry was picked up in resolv.conf when I cycled the 
interface.  This was better but surprisingly only marginally so.

3.) another person declared that he had 'fixed' his 'Ubuntu' DNS issues by 
upgrading to Hoary.  I didn't believe this would help as I was seeing issues 
with DNS latency in Debian Sarge too.  Naturally, I didn't like to think it was 
a "Debian" issue, but had no other linux flavour installed to test this.  As 
already mentioned above, Windows XP was unaffected.

3.) a friend of mine found this posting (abridged)......
<SNIP>
if you're getting slow DNS lookups with Ubuntu (especially if using
something like djb's dnscache), edit  /etc/modprobe.d/aliases and
modify the net-pf-10 line to look like this:

alias net-pf-10 off ipv6

you'll need a reboot, as IPv6 will be "in-use" by a number of things,
and modprobe -r won't do the job.
<SNIP>

I followed this chaps advice, but, frustratingly, it had no effect :(

4.) I tried substituting a D-Link DSL-302G that I borrowed.  What do you know? 
All was fine!


Solution:

Finally on the right path, I searched the Netgear knowledge base and forums, but 
found nothing of use.  The firmware I had was the latest official release 
(1.05.00).  I did find a beta firmware revision (2.10.09), but there was no 
support for this at all.  I decided to call Netgear first to see if anyone there 
had seen this problem before, or had access to support information that wasn't 
posted on their site.  Long story short, they hadn't and when I mentioned I was 
using Linux, they decided to defer any further personal assistance and opened a 
'special' call for me with no eta for a fix (ironic when the device runs linux 
natively, I thought.)

Getting a bit desperate, I decided to install the unsupported beta firmware 
(version 2.10.09) ....  and all is good!  Everything now works as it should, and 
for an added bonus it now (quote) "Adds support for five IPSec VPN tunnel 
endpoints" too!

Obviously, I cannot vouch for long term stability using this version, but I wish 
I had tried this sooner.  To be fair, everything up to point 4.) above had 
pointed to Ubuntu having DNS issues, further sullied by users reporting firefox 
having problems, too.  I don't suppose I will know *exactly* what the problem 
was until I can get hold of the changelog for this firmware revision, but I 
decided to post feedback direct to Netgear and also risk a red face by posting 
my findings to a few forums in the hope that it will shortcut the process for 
others.

Cheers,
-- 
Colin Templeman
@ home - Wellington - New Zealand
"Teach it Phenomenology, Doolittle".

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