Network Config Error--help!

[Stefan Bruda]

Hi.

At 16:36 -0500 on 2003-5-19 Jason Hardcastle wrote:
 >
 > Ok, I just installed YellowDog 3.0 on my Pismo (500 MHz, 1 GB RAM,  
 > AirPort) and I can't get it to connect to the net at ALL.
 > 
 > I've tried via ethernet straight into the cable modem, and still  
 > nothing.

I am not familiar with the RH tool (maybe somebody else can shed some
light), but in case you cannot make it work here is what you need to
do from the command line using the most low-level tools you get (in
other words if they do not work then the problem is quite deep
probably).

I refer to ethX with the understanding that this is usually eth0 (for
the Ethernet NIC) or eth1 (for the Airport card).  In the wireless
case, you have to go through the wireless configuration (which has
been documented on this list and in YDL howtos) before doing the
following steps.  The programs you need (ifconfig and route) are both
in /sbin, so read /sbin/ifconfig and /sbin/route instead of ifconfig
and route, respectively if /sbin is not in your search path.

If you use a DHCP server, things are really easy.  Go as root to a
terminal and type

    ifconfig ethX up
    dhcpcd -d ethX

and you are in business.

If no DHCP server is available, read on.  Things are a bit more
lenghty but not as scary as they look.  Go as root to a terminal and
do

    ifconfig ethX aaa.bbb.ccc.ddd netmask yyy.yyy.yyy.yyy

where aaa.bbb.ccc.ddd is the IP address you want to assign to your
machine, and yyy.yyy.yyy.yyy is the netmask.  For example, my tibook
has the address 192.168.0.3 and the netmask is 255.255.255.0 so that
only the machines 192.168.0.x, with 0 < x < 255, are considered on the
same subnet, so I do

    ifconfig ethX 192.168.0.3 netmask 255.255.255.0

Now you want to add routes to the machines on the same subnet.  Do

    route add -net aaa.bbb.ccc.0 netmask yyy.yyy.yyy.yyy ethX

Note the last part of your IP address being replaced by a 0.  This
says that all the traffic between your machine and its other fellows
on your subnet (e.g., the DSL/cable modem/router) goes directly
through ethX.  In my example, I do

    route add -net 192.168.0.0 netmask 255.255.255.0 ethX

Now for the rest of the world.  One of the things on your subnet is
the contact between you and the rest of the world.  We instruct the
machine to redirect all the traffic that goes outside your house to
this machine.  The machine has two IPs, one for the subnet the other
for the rest of the world.  You do not care about the latter.  Do

    route add default gw eee.fff.ggg.hhh ethX

where eee.fff.ggg.hhh is your router's address for the internal
network.  This says that by default the traffic goes from your machine
to, say, www.ydl.net through the gateway (gw) eee.fff.ggg.hhh.  In my
case, I configured my DSL modem/router to be 192.168.0.254 for the
internal net, so I would do

    route add default gw 192.168.0.254 ethX

Now you are connected (one hopes).  You can access, e.g., www.ydl.net
but only using its IP address (which incidentally is 66.7.161.9).  You
still have no name resolution.  To get such, edit (create if
necessary) the file /etc/resolv.conf.  Place at least one line in
there, which should read

nameserver iii.jjj.kkk.lll

This would be the machine that takes care of names and translates them
into IP addresses.  If your modem (eee.fff.ggg.hhh) does DNS duty
(most of them do), you could put in there

nameserver eee.fff.ggg.hhh

otherwise, put in there whatever nameserver your ISP tells you about.
This line can be repeated with different IPs, case in which the second
occurrence will be used in case the first is not available, and so on.

Of course, you should provide the IP address of the nameserver, not
the name, since there is nobody to translate the name for you.

For the gory details (and detailed information about what all of these
mean) go to http://www.tldp.org/HOWTO/Net-HOWTO/index.html

Hope this helps,
Stefan

-- 
If it was so, it might be; and if it were so, it would be; but as
it isn't, it ain't. That's logic.
    --Lewis Carroll, Through the Looking-Glass