Re: Second ethernet card seems to cause networking failure?
On Fri, May 22, 2009 at 09:25:29AM -0700, Frank Miles wrote:
> I recently added a second networking card to a hardware-test PC. This elderly machine
> had been working reasonably well. The second networking card is for eth1, etc., and
> /sbin/ifconfig shows things as properly connected, with eth0 being the outside interface
> and eth1 being an internal 192.168.x.x interface for some special internal systems that
> have absolutely no need to communicate with the outside world, just this one PC.
So now you have a gateway?
What firewall configuration software are you using?
What is the output of "cat /etc/network/interfaces"
> The weird thing is that with normal booting configuration, pinging INet addresses
> fails. This seems to be related to the order in which the interfaces come up: doing
> ifdown eth1 ; ifdown eth1 ; ifup eth0; ifup eth1
> causes pings to fail; but if eth0/eth1 are reversed (bringing up eth0 last), or eth1
> is simply suppressed, pinging URLs works (i.e. ping www.debian.org).
Have you a local DNS server?
> Regrettably this last does not entirely solve things - for example, I cannot do system
> updates: "apt-get update" fails to connect.
Error? times out? unable to contact … ?
> Eventually, if I play around long enough (killing eth1, killing my firewall - which
> hasn't changed since before adding the second NIC,...) I can do a system update
> but it's not entirely clear what the critical steps were to get that working.
killing the firewall mmm ...
> I freely admit that I'm a hardware guy - I don't know much about networking.
I don't know much about networking either but if I was asking this
question I'd provide at least the config files (see above), exact error
messages from logs (if any … if none say so.), exact messages on screen,
(if none, say so)
> Does anyone have a suggestion on where I might look to get this working properly?
> Without sacrificing eth1? Or at least some better diagnostic[s] to track down
> where packets are getting lost?
Of course, I'd only post to this list after I'd used "apt-cache search
network test | wc -l" and saw that it shows 83 packages which fit that
search criteria and see that there is not really anthing useful, ok
there is "ping", but you've already used that.
So I'd try "apt-cache search network diagnos | wc -l" ok 14, and see …
that there is nothing very useful.
We're at the mercy of the package maintainers to at least put some
decent search terms in the descriptions and not just copy a paragraph
off the upstream website or manpage.
So I'd state I'd searched the packages and didn't really see anything
useful.
Also describe the network a bit more -DSL? Is this the first time you
are connecting to the net with this machine etc.
You may then get a response from someone who sees an anomaly with
your setup, and might even help.
But, and this is a stab in the dark, I think you have to tell the
firewall about your new interface.
--
Chris.
======
I contend that we are both atheists. I just believe in one fewer god
than you do. When you understand why you dismiss all the other
possible gods, you will understand why I dismiss yours.
-- Stephen F Roberts
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