Cannot Surf Internet, but I can Ping

[Eric Dunbar]

On 1/28/06, Tod Merley <todbot88 at gmail.com> wrote:
>
> >
> > Date: Fri, 27 Jan 2006 21:25:12 -0500
> > From: Eric Dunbar < eric.dunbar at gmail.com>

> > Hmm. Now I wonder. Here's my situation.
> >
> > I have an ADSL modem set to bridge mode. A Netgear 614MR router
> > (802.11g) acts as a router for the network and also establishes the
> > PPPoE connection.
> >
> > When I had the ADSL modem active as the DHCP server (i.e. not in
> > bridge mode) the Netgear router would function adequately as a
> > secondary router.
> >
> > After I put the ADSL modem into bridge mode [1.1] and I used the
> > Netgear 614MR to login to the ISP using PPPoE, I had the strange
> > behaviour -- my computers (one Linux (YellowDogLinux 4.0.1 (FC2+3),
> > two Mac OS X 10.4.4) would resolve URLs VERY, VERY slowly but once
> > resolved browsing (or any other DNS lookup function that required
> > access to the wider world) would function OK.
> >
> > However, if I removed the router from the equation and logged in using
> > Mac OS X 10.4.4 everything would work beautifully -- I'm not sure if
> > OS X 10.4.4 would have been using IPv6 or not since a quick look at
> > the settings has the default as being "automatic" but I suspect it was
> > using IPv6 ... and, I won't test it right now b/c I've got an audio
> > capture happening on my Linux server for CBC radio 1's "Ideas" (I've
> > got a nice collection of ideas going :-)
> >
> > When I took the DNS servers as reported by the Router Status page (in
> > Internet Port:Domain Name Server) and entered them into the "Basic
> > Setup" page I could once again use the router as a go between between
> > the computers and the modem.
> >
> > [1.1] The ADSL modem is now unfortunately PERMANENTLY in bridge mode.
> > I cannot for the life of me figure out how to reset it (no little
> > button anywhere on the outside... haven't tried opening it up yet)
> > and, an e-mail to the manufacturer came back with a response "Contact
> > your ISP. Some modems shipped with that functionality enabled." (I put
> > it in bridge mode ;-). Fortunately, I have another ADSL modem that's
> > mine so I'm OK if I ever want to have a non-bridge connection ;-).
> >
> > Hmm. Is the problem IPv6?
> >
> > Eric
> >
> Hi Eric!
>
>  I had been chaseing the problem for months, and had asked several network
> professionals about it.  Thier advice to set up tcpdump and analyze with
> ethereal proved very good.  The truth is that my packet capture size was too
> small to catch the actual full response to firefoxes DNS requests, however,
> the "1.0.0.0" reply back told me that something was not properly resolved.
> A forum search on DNS and Firefox clued me in to the rest.
>
>  In my case I believe I am dealing with old firmware (faulty, I would say)
> in the provider owned DSL modem.  Simply, it improperly handles IPv6 DNS
> requests.  In your case resolution is slow but there.  Ethereal would show
> you what is happening where and when, and I think that would be good to do.
> There are probably other tools as well.
>
>  Perhaps it would be best to set up a separate DNS server on an unloaded box
> on your network.  Might very well improve resolution times.
>
>  Just some thoughts!

Ok, am looking at tcpdump output on my Mac OS X box and it's a bit of
gobble-di-gook (no ethereal installed here ;-). I'm not going to
jeapordise my machine with Fink or Darwinports (allow for OSS to be
installed automagically as per apt (they may even use apt for all I
know ;-)) so I'll have to see if ethereal on YellowDog will read the
tcpdump from Mac OS X (which, I assume it will).

Anyway, now that I made that one change in the configuration of the
router (a few days ago now), I'm no longer having problems with URL
resolution times. (though, it's good to know about tcpdump because I
do occasionally have problems which probably could be diagnosed with
tcpdump).

Thanks for the pointer.

Eric.