[Linux-disciples] getting online

Adam Rosi-Kessel adam at rosi-kessel.org
Fri Feb 4 08:48:07 EST 2005

The trick with this sort of problem--and really 99.9% of linux
problems--is drilling down to the problem area. One of the problems I
consistently see with newer users is that they feel helpless because
they don't know at which layer the problem is arising.

So there are a few questions:

(1) Does your computer see your network card?
(2) Does your network card see the wireless signal, and associate with
the wireless router?
(3) Does your network card get an IP address from the wireless router?
(4) Does the wireless router see the "Ethernet modem" (I assume you mean
cable modem)?
(5) Does the cable modem see the Internet?

It sounds like (4) and (5) are yes if Anne's Windows laptop gets on the
Internet. So let's focus on (1), (2), and (3).

You also are more or less sure of (1), since your card was working
before you moved.  But it's essential to be absolutely sure.

eth0 is an odd name for a wireless interface--if your computer has a
built-in network card, that would be eth0, and the wireless would be
something like eth1, ath0, wlan0, etc., depending on the driver it uses.
I have a suspicion that the eth0 line is actually a wired network card,
which is why you're not getting any response.

Check dmesg and /var/log/syslog and see if you see any mention of your
wireless network card.

If you're using a network card that has proprietary firmware, it won't
be in Debian and you have to get it/build it yourself.  When I visited
you in Chicago, I seem to remember you needed the madwifi drivers for
your wireless card.  If you are using that same card, you will need
those same drivers; they should continue to work from your old
installation, unless you've upgraded your kernel, in which case you have
to rebuild them for the new kernel.

There is a Debian package, madwifi-source, that gets the source code for
the drivers and helps you build it. (One of the nice advantages of
Ubuntu is that it's not as dogmatic about this stuff and just includes
the drivers).

If you are using madwifi, the interface name will be ath0.

To see if an interface exists at all, just type

ifconfig <interfacename>


ifconfig ath0
ifconfig wlan0
ifconfig eth1

See if any of those give you any result.

If they do, then eth0 is not your network card.

Once you've identified your network card interface name and are certain
it is working, you can move on to (2).

iwconfig is the command for controlling the wireless aspects of your
network card.  Start out with

iwconfig ath0

(or the name of your network interface)

It should tell you if it sees the wireless router, because you'll see
the name of the router.

If not, you can try

iwconfig ath0 essid any

Which generally means 'attach to any wireless network you can find'.

You can also try

iwlist ath0 scan

Which should list available access points.

If you are attached to a wireless network, try

pump ath0

That will get you an IP address and routing information.

I actually recommend dhclient over pump, but you'll have to be online
before you can download that package.

Once you're (1) associated with the wireless network and (2) have an IP
address, if you *still* can't access the Internet, you can try (1)
pinging the router, (2) pinging other hosts in your LAN, (3) pinging (or
web browsing) to hosts by their IP address rather than domain name (in
case it is a DNS problem).

Once you have this all figured out, you can save the settings
permanently in /etc/network/interfaces.

Incidentally, it's also a good idea to try booting from the most recent
version of Knoppix or Ubuntu Live and see if you get network
connectivity that way. They both include more drivers and better
auto-configuration, so it can be a quick way to see what the proper
configuration should be.  If you can get everything working
automatically with Ubuntu Live, it should be quite easy to replicate
that with Debian.

And keep asking questions as you go along--it's easier to answer once
you've drilled down to a particular problem area.

Karl Sokol wrote:
> I confess that despite copious reading and experimenting, I have yet to
> understand how to get online on Debian.  I have a wireless service that
> goes through an Ethernet modem, a wireless router and then into my
> interface card.  I am more or less sure the interface card is set up
> O.K. because it worked before we moved.  I have a connection on my
> wife's Windows based laptop.
> My /etc/network/interfaces file looks:
> "auto lo
> iface lo inet loopback
> iface eth0 inet dhcp."
> ifup eth0  gives "ping ( 56 data bytes"
> and then says 100% packet loss.
> ping gives 0% packet loss. I have pump installed, but do not
> know how (or if I need to) configure it.
> Am I barking up the wrong trees?  Is there a site that has a nuts and
> bolts howto get online without having to read for the umpteenth time
> about the history of networking?
> Forever indebted,
> Karl
> _______________________________________________
> Linux-disciples mailing list
> Linux-disciples at lists.bostoncoop.net
> http://lists.bostoncoop.net/mailman/listinfo/linux-disciples

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