Internet Access has been knobbled

[Colin Law]

On 22 March 2017 at 13:53, Gary Taig <taig at melbpc.org.au> wrote:
> On an old machine (10.04), from which I wish to collect (forward) all my old
> email, I'm finding things have changed.  When I start the old Firestarter,
> it reports "ETH0 is not ready".
>
> There is an 8-port Ethernet Switch between the computer and the modem. To
> retain all other functionality but cut the Internet I used to simply cut
> power to the switch.
>
> Anyway, there is no packet activity whatsoever, through the switch or to the
> modem and the aspect that makes this highly suspicious is that after I've
> started FireFox and attempted to connect to a server, ANY SERVER, and it
> reports that it cannot connect and invites checking to ensure FF has
> permission to access the Internet etc. THEN...  I find FF has defaulted to
> working offline.  I fix it, close FF and restart, and without my
> intervention it has been again set back to "working offline"
>
> SOMETHING IS INTERFERING...SOMEWHERE
>
> ifconfig reports as follows:
>
> eth0      Link encap:Ethernet  HWaddr 00:25:11:1a:ed:ee
>           UP BROADCAST MULTICAST  MTU:1500  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
>           Memory:feac0000-feae0000
>
> lo        Link encap:Local Loopback
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           inet6 addr: ::1/128 Scope:Host
>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>           RX packets:658 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:658 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:53748 (53.7 KB)  TX bytes:53748 (53.7 KB)
>
> What settings can I check to identify/isolate the problem?

As Liam points out it is not getting an ip address from the modem
(assuming that is a DHCP server). I would first try running a
different ethernet cable direct from the PC to the modem and see if it
works then. That will rule out the cables and the switch.

Colin