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Re: [LUG] Router problem - maybe not.

 

Neil Winchurst wrote:
> On Tue, 05 Sep 2006 09:12:50 +0100
> Neil Williams <linux@xxxxxxxxxxxxxx> wrote:
> 
>> (If you're not sure, copy the contents of /etc/network/interfaces in a
>> reply.)
>>
> I don't have this file on the computer.

Then you'll have a similar file - perhaps Robin or someone else who has
used Mandrake/iva recently can say what file is used instead. Basically,
this file dictates how your computer sets up that end of the network
connection to the outside world. If this is the only machine unable to
use the local network as originally planned, the problem is usually
related to this file.

It contains things like:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# This is a list of hotpluggable network interfaces.
# They will be activated automatically by the hotplug subsystem.
mapping eth1
        script grep
        map eth1

# The primary network interface
auto eth0
iface eth0 inet static
        address 192.168.0.10
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255
        gateway 192.168.0.7

The gateway setting sets the value that I was checking via the route
command.

>> It sounds like the PC is booting with the wrong config - to the point
>> where it cannot find the network connection. Follow Robin's advice and
>> isolate *which* components of the network are still working before you
>> reboot the router.
>>
> But, in that case, why did it all work OK for three months?

Because something you installed/configured/removed in that time has
changed the setting on the PC.

>> Check the boot messages for DHCP commands which may be overriding your
>> config.

Did you do this (on the PC)?

>> Also, check /etc/resolv.conf which may have been overwritten. This would
>> make it hard to locate local devices and could disable DNS resolution if
>> the local nameserver cannot be found.
>>
> I don't have this file.

Again, you'll have something similar. /etc/resolv.conf usually contains
something like:
search codehelp
nameserver 192.168.0.2

In my case, it tells the machine to append .codehelp to all local
addresses in order to resolve them (so that ssh holly actually becomes
ssh holly.codehelp which then resolves to 192.168.0.10) and it specifies
the IP address of the machine running your local DNS that resolves these
names into IP addresses.

Are you running a static IP at all?

>> If you set your local DNS on the router, the IP address of the router
>> should be your nameserver. If you run bind on the PC, the nameserver IP
>> should be the static IP of the PC.
>>
> I don't understand all that. The router was set up for me. All I did
> was plug it in to the computer and it worked.

Then you are probably using DHCP. It may just be that your DHCP client
is barffing on startup and needs to be restarted. It may be that this
package has been updated and is now complaining about something in the
config that was previously handled.

Try:
# /etc/init.d/dhcpd restart
(or equivalent on Mandriva)

(Off-thread: I wish Mandrake/iva would stop changing filesystem issues
like this - and quit patching the kernel so much too!)

> I ran /sbin/route and have attached the output

That's fine.

> Meanwhile....my wife has her laptop downstairs and uses a wireless
> connection to the router. This is still working fine, with no need to
> reboot the router. Is that significant?

No, except that it tends to mean that the problem is on the PC NOT the
router.

Instead of rebooting the router, next time try these commands on the PC:

# ifdown eth0
# ifup eth0

It's the old GNU trick of restarting a single service instead of an
entire machine. Only Windows requires a complete restart of an entire
machine, you should avoid rebooting the router if at all possible,
especially as it does NOT appear that the router is actually the device
that has the problem.

-- 

Neil Williams
=============
http://www.data-freedom.org/
http://www.nosoftwarepatents.com/
http://www.linux.codehelp.co.uk/


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