Cannot Surf Internet, but I can Ping

[Tod Merley]

>
>
> Date: Fri, 27 Jan 2006 21:25:12 -0500
> From: Eric Dunbar <eric.dunbar at gmail.com>
> Subject: Re: Cannot Surf Internet, but I can Ping
> To: Ubuntu Help and User Discussions <ubuntu-users at lists.ubuntu.com>
> Message-ID:
>         <77520bee0601271825v399e8afak193f31c73c2dcfee at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Ok, see what follows post ;-)
>
> On 1/27/06, Tod Merley wrote:
> > Please see what follows post:
>
> > I had a similar problem as follows:
> >
> > HI List!
> >
> >   The FC4 box (a desktop) attached via DHCP fine.  Then the problems
> > started.
> >
> >   I noticed that Konqueror would browse (and Kget would download) fine
> but
> > Firefox would browse intermittently (actually not very often and almost
> > never to any major sites such as google.com or yahoo.com).
> >
> >   The problem did not exist when the computers were used outside of the
> > Quest DSL home.
> >
> >   A look at a network traffic recording (tcpdump -w & Ethereal) showed
> that
> > DNS queries from Konqueror were answered properly but DNS queries from
> > Firefox were either resulted in a server-fail reply or in an apparent
> reply
> > address of "1.0.0.0".  When Firefox replied with the "1.0.0.0" address
> the
> > network never replied and the system timed out.
> >
> >   If IPv6 DNS was disabled in Firefox (Using "about:config" in the URL
> line
> > then setting "network-dns-IPv6-disable default Boolean false"  to
> > "network-dns-IPv6-disable User Set  Boolean true") then Firefox browsed
> > fine. It appeared that we had an IPv6 DNS problem.
> >
> >   Now, in Fedora if you disable IPv6 (add "alias net-pf-10 off" to
> > /etc/modprobe.conf and reboot) then Firefox will browse fine "dns-IPv6"
> in
> > Firefox set or not. But I had changed to Ubuntu on the main machine
> since it
> > was more compatible with some of the software I desire to use.  I found
> no
> > successful way to disable IPv6 in Ubuntu.  I did, however, happen across
> one
> > who mentioned that disabling the use of the DSL modem as a name server
> > eliminated the faulty DNS queries.  Indeed, a simple "# " added to the
> > "nameserver 192.168.0.1" line in the "resolv.conf" file in "etc" cured
> the
> > network connection problems for internet access from the Ubuntu machine
> > completely.
> >
> > Probably I will leave the Fedora machine with IPv6 disabled and the
> Ubuntu
> > machine with IPv6 enabled but taking care to see that Ubuntu does not
> use
> > the DSL modem DNS.
> >
> > I hope this is useful!
> >
> > Cheers!
> >
> > Tod
>
> 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!

Tod
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