Re: [Sheflug] Re: Routing Problem

["Alex Hudson" <nospam [at] alexhudson.com>]

> # ISDN (i4L)
> # 192.169.0.1       0.0.0.0   255.255.255.255     ippp0
> # default           192.168.0.1
> 194.247.47.47       0.0.0.0   255.255.255.255     ippp0
> 192.168.1.0         0.0.0.0   255.255.255.0       eth0
> default             192.168.1.1
>
>
> Looks to me like YaST doesn't want to let me know what's going on here
> :(
>
> Issues....
>
> Why is it that eth0 appears to be set as 192.168.1.0 when I've set it
> as 192.168.1.1 ?  When it shouldn't be.

That's not quite what's going on here.

192.168.1.0         0.0.0.0   255.255.255.0       eth0

192.168.1.0 is the network address. 255.255.255.0 is the netmask. Hence, any
packet destined for 192.168.1.(whatever) matches this rule. eth0 is set as
the interface, i.e. 'you will find the 192.168.1.* network on the other end
of the eth0 interface'.

> The bit at the bottom which says..  "default   192.168.1.1"   Should
> that be 194.247.47.47 ?  I've looked at man route.conf and that says
> the route.conf file is configured properly.

It should *possibly* be 194.247.47.47.

Let's take this one step at a time. First step; forget about the network,
get the isdn machine working.

Let's assume your dial-up and everything is configured correctly. I'm also
assuming that 194.247.47.47 is the machine on the other end of your isdn
line - is this the case? Sometimes, it's allocated dynamically, like a modem
dial-up, and changes from connection to connection. So, log onto the machine
with the isdn (if your network isn't functioning, you'll have to do this
from a local console). Bring up the isdn connection. From *that* machine
(not one on the network), attempt to ping your isp, and well-known internet
sites (www.demon.net, etc.). I'm assuming that at the moment this isn't
going to work. So, change the default route, either through yast, or at the
command line:
    route del default gw; route add default gw 194.247.47.47 ippp0
(check the command line options, I haven't used route in yonks)
The default route should now be set to 194.247.47.47. Now try pinging sites
on the internet. This should now work, assuming the information you've given
is correct. If it does not, you're missing something necessary from you
dial-up configuration, and that is the part that isn't working. If at this
stage it still isn't working, do a traceroute and send us the results. Pick
any old internet address, 200.199.199.200 will do fine, and force a
traceroute out of your isdn line. The command would be something like:
    /sbin/traceroute 200.199.199.200 -i ippp0
. but again, check the command line options, b'cos it's not something I use
often. This will (hopefully) give you some information about the computers
at the other end of your dial-up, which may give some hints at why it isn't
working.

So, onto the network problem. Firstly, on the client machines, get rid of
any non-default route information: that means default gateways, static
routes, anything else you might have in there. Just make sure the machine is
configured with the correct ip address in the 192.168.1.n range, being
careful that n is *not* 0 or 255 ;) No gateway, no nothing else, it won't
need it. A 'netstat -r' will again show the eth0 route to the 192.168.1.*
network. A 'ping 192.168.1.1' definitely ought to work. Set ping going, and
if nothing is coming back, see if the lights are flashing on the hub & isdn
machine. If it's not working, on one virtual console run '/sbin/tcpdump -i
eth0', and on the other run ping again. Go back to the tcpdump console  - if
stuff is happening, and every line has a '>' in it, your machine is working
fine. If there's an equal number of lines containing '<' then you have some
dodgy packet filtering rules or something which are stopping you seeing the
pings on the local machine. Assuming they're all '>' lines, then the problem
is with the other machine (given the netstat output previously, though, I
don't think this is the case, unless again you have dodgy packet filtering
rules in place).

There's some stuff to be going on with, anyhow ;)

Cheers,

Alex.

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