[Techtalk] DNS problem with wireles internet

[Wim De Smet]

Hi,

On Thu, Aug 12, 2010 at 10:15 AM, David Sumbler <david at aeolia.co.uk> wrote:
> That's solved it - thanks.  Permissions on /etc/resolv.conf were 700: I
> have changed this to 744, although 644 would seem to make more sense,
> and I notice that on my desktop computer I have 666.

Mine's set to 644, which seems to be the correct option (it should not
be executable, and there's no need for regular users to be able to
write to it).

> The file contains one entry (as does the same file on my desktop
> computer) referring to 192.168.0.1 .  I assume that this means that
> wireless routers must always be set up as 192.168.0.1 if they want
> occasional users to be able to log on easily.  Perhaps someone could
> confirm this for me.  My home router is set up that way because that's
> just the way I happened to do it, and it seemed a sensible choice.  I
> did not realize it was a necessary choice for wireless connections.

The file is updated by NetworkManager (NM). Basically, NM picks up the
address from DHCP and writes it in there, so it should always be up to
date according to what your local DHCP server (usually your home route
in this scenario) tells you. (when getting an IP through DHCP, the
router sends you your lease information for your IP, which includes
the nameserver information). You can always test it by chaning your
router's IP. :-)

As an aside, in situations where that information is not available
through DHCP either static addresses are used or an attempt is made to
use zeroconf services (through avahi on linux) to figure out the
correct IP for your DNS servers.

I hope all this clarifies some things.

regards,
Wim

> On Thu, 2010-08-12 at 09:54 +0200, Wim De Smet wrote:
>> That is odd.
>>
>> The nameserver addresses should be written to /etc/resolv.conf. Check
>> what it says. If you know the router IP you could try using dig
>> (dnsutils package, not sure if it's installed in 9.04) to query it
>> directly. On the command line:
>> dig @IP <somehost>
>>
>> Considering that it works as root, perhaps check if /etc/resolv.conf
>> has the right permissions (should be readable for everyone).
>>
>> cheers,
>> Wim
>>
>> On Thu, Aug 12, 2010 at 2:31 AM, David Sumbler <david at aeolia.co.uk> wrote:
>> > Further to my earlier message (below), I have discovered that if I log
>> > in as root, I can get internet access.  But when logged in as a normal
>> > user, I can't.
>> >
>> > And I still can't figure out the answer, though!
>> >
>> > David
>> >
>> >
>> >
>> > On Wed, 2010-08-11 at 23:44 +0100, David Sumbler wrote:
>> >> I have just received a new psiXpda computer - a sort of hand-held PC.
>> >> The makers offer it with Windows XP or Ubuntu 9.04; needless to say, I
>> >> chose the latter.
>> >>
>> >> The problem I am having is with connecting to the internet.  The device
>> >> is connecting wirelessly to my router, and DHCP is working: the computer
>> >> can report its own IP number, the router reports the computer's
>> >> presence, and I can log into the router from the computer.  So far so
>> >> good.  But DNS does not seem to be working.
>> >>
>> >> My desktop PC is connected to the router by an ethernet cable, and is
>> >> set to use the router as a DNS server, which has a fixed IP address on
>> >> my network.  The router, of course, knows the addresses for my ISP's DNS
>> >> servers.
>> >>
>> >> That all works fine, but presumably with a wireless connection a
>> >> computer needs automatically to send DNS lookups to the router it is
>> >> currently connected to, whatever IP address the router has.  Putting an
>> >> IP address for the router into a file on the computer obviously won't
>> >> work.  Incidentally, my iPhone works wirelessly with the router, and
>> >> doesn't have a problem connecting to the internet.
>> >>
>> >> Unfortunately it is now well out of office hours, so I can't contact the
>> >> suppliers of the computer to ask if they know how to solve the problem,
>> >> and they can be difficult to get hold of at the best of times.
>> >>
>> >> So can anyone point me in the right direction as to how to get DNS
>> >> working?
>> >>
>> >> David
>> >>
>> >
>> >
>> >
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