Network Connection problems after Upgrade to 10.04 LTS, from 08.04 LTS

[NoOp]

On 05/11/2010 03:09 PM, Jay Ridgley wrote:
> Folks,
> cc:NoOp
> 
> The laptop I am using is a Dell Latitude C610. I have a Linksys Wireless-G card 
> WPC54GS ver.2 as well, however the connection I am trying to make right now is a 
> plain vanilla eth0.
> 
> I have no other OS available on the system. I do not have a liveCD available.
> 
> I double checked /etc/hosts, /etc/network/interfaces and /etc/resolv.conf agree 
> with the other systems in my network.
> 
> 
> ifconfig shows: (as desired)
> 
>   Inet addr:192.168.139.8 Bcast:192.168.139.15 Mask:255.255.255.240
> 
> it is up and running I can ping my nameserver/gateway, however, none of the 
> other systems or the outside world is reachable. Nor can I ping the laptop from 
> one of them, other that the nameserver/gateway
> 
> There is some external traffic since the Invest applet is being updated.
> 
> I have noted a route that should not be present, at least it is not on my other 
> systems. How can that route be removed? I have tried to issue a route del 
> command but evidently I do not have a proper request created because the command 
> returns an error SIOCDELRT: No such device and nothing is changed. The command I 
> am using is:
> 
> sudo route del 192.168.139.0 mateo
> 
> 192.168.139.0 mateo is not a route present on my other systems.

Do you still have your emails from Feb/March: "Help with content of
/etc/network/interfaces file"?

Unfortunately, because those were not in a single thread it would take
too much work to cobble all of them together for a response. However, at
the time I recall that you were messing about with Firestarter etc., and
finally managed to get things working:

<quote>
A couple of things were giving me fits...

1. NO DHCPOFFERS - I discovered a how on www.ubuntugeek.com that
contained information on trouble shooting network connections and used
several pointers I found there to resolve that issue.

2. Firewall problems - I was using Firestarter and was having problems
with getting out side my local network. I solved that problem by
bringing up Shorewall.

I am able to use my laptop on my wireless sub net now.
</quote>

And:
http://osdir.com/ml/ubuntu-users/2010-02/msg02931.html
Note that your mask is still
Mask:255.255.255.240
That in itself is OK if you are only expecting 16 IP's on that subnet &
192.168.139.8 certainly falls within that range (192.168.139.0 -
192.168.139.15) so that's not likely the problem - as long as the
gateway is as well, but worth keeping in mind.

I suspect the same issue may have raised it's head again. You might want
to flush the IP tables & see if that cleans things up:
https://help.ubuntu.com/community/IptablesHowTo
<http://www.prash-babu.com/2008/10/how-to-flush-or-remove-all-iptables.html>