[lug] Problem with resolving

[Stephen Queen]

On 12/2/05, Lee Woodworth <blug-mail at duboulder.com> wrote:
> Stephen Queen wrote:
> > I just changed ISP's. I now have an Actiontec DSL modem connected to
> > my Linux gateway machine. The Linux gateway machine acts as my
> > router/firewall. On the inside network I have 3 more linux machines.
> > Two of them are running Slackware and the other is running Debian. The
> > two Slackware machines seem to be working just fine. I can access the
> > web just like with my old ISP. The Debian machine seems to not resolve
> > outside addresses correctly.
> >
> > One of the first things I tried was to boot the machine with knoppix
> > and configure the network with the same parameters and it worked.
> Including the same /etc/resolv.conf, /etc/hosts and firewall rules?

I only did this with the Debian machine that wasn't working correctly.

> Is your gateway box running a caching dns server that
> does recursive lookups for your local clients?

No.

> >
> > Booting back to Debian I then tried ssh'ing to a remote account. It
> > resolved the name  correctly and allowed me to log on.
> >
> > I then tried a traceroute, and got the normal results.
> >
> > I can also do a dig to a host name and get the correct results. But if
> > I enter the URL for a web site on a browser it still doesn't resolve
> > correctly.
> Is this on the gateway machine?

No. This is on the Debian box that doesn't work.  All the other
machines appear to work correctly.

>
> >
> > I then tried to wget to a web site. It came back saying the URL
> > resolved to 1.0.0.0.
> > I did a dig on the same website, got the correct IP Address and tried
> > again with wget using the IP address. It downloaded the index.html of
> > that website.
> >
> > I then did a strace on wget using the URL. I could see that it does in
> > fact access the nameserver but returns with the IP of 1.0.0.0.
> >
> > I did an arp, and it looks like my IP's do map to the correct mac addresses.
> >
> > Any suggestions?
> Probably an issue with /etc/resolv.conf on the gateway, and
> maybe on the clients.
>

The resolv.conf is the same on all four machines. It is working on
three of them. I have not completely ruled out anything yet. I have
looked at what I consider the usual suspects. The reason I don't
believe its the firewall, is because 2 of the client machines are that
working fine, and when running knoppix the Debian machine runs fine.

Examining the network configuration on the Debian machine, shows the
expected results, as does the routing tables. (Using route, rather
than the iproute2 tools -- I haven't used those because they're not
installed on the machine, and I can't get them with synaptic because
of this problem. Yes that's a lazy persons excuse.)

Thanks,
Stephen Queen