Recovering broken system

[Kevin O'Gorman]

On Wed, Oct 26, 2011 at 5:05 AM, Joseph Loo <joseph.loo at dslextreme.com> wrote:
> On 10/25/2011 11:32 PM, Kevin O'Gorman wrote:
>>
>> The problem: I configured my two ethernet interfaces, and they seem to
>> be up, but they don't work.  I think it's that the kernel routing table
>> has no gateways configured, since
>> my attempts to configure routes in  System->Preferences->Network
>> Connections do not appear in the results of "route -n".  I'm probably
>> doing something really stupid,
>> or not doing some simple but required thing, but someone will have to
>> tell me what it is.
>>
>> Help?
>> --
>> Kevin O'Gorman, PhD
>>
>>
>>
>
> Do /sbin/ifconfig. see if the ethernet connection is configured properly. It
> should have your ip-address shown somewhere. Mine shows up like this
>
> /sbin/ifconfig
> eth0      Link encap:Ethernet  HWaddr 00:1C:C0:8E:16:52
>          inet addr:192.168.21.15  Bcast:192.168.21.255  Mask:255.255.255.0
>          inet6 addr: fe80::21c:c0ff:fe8e:1652/64 Scope:Link
>          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>          RX packets:10576121 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:14942795 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:1000
>          RX bytes:7067333300 (6739.9 Mb)  TX bytes:6104087688 (5821.3 Mb)
>          Interrupt:27 Base address:0xe000
>
> 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:11520219 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:11520219 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:0
>          RX bytes:15095242989 (14395.9 Mb)  TX bytes:15095242989 (14395.9
> Mb)
>
> wlan0     Link encap:Ethernet  HWaddr 00:1D:6A:44:DB:83
>          inet addr:192.168.20.15  Bcast:192.168.20.255  Mask:255.255.255.0
>          inet6 addr: fe80::21d:6aff:fe44:db83/64 Scope:Link
>          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>          RX packets:11392824 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:115191 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:1000
>          RX bytes:3538175720 (3374.2 Mb)  TX bytes:1371190 (1.3 Mb)
>          Interrupt:21


I can have the right info, and still have things not work.  Most of
the time it appears that it helps to do "ifconfig eth0 down" and
"ifconfig eth0 up".  Most of the time.  I get the impression that
sometimes just waiting helps, though I'm less sure of that one.  Some
of my problems turned out to be with the default route, which ifconfig
does not show; I use "route -n" for that.  Sometimes things have hung
because of the name server IPs.  I still have no idea why they show up
in /etc/resolv.conf sometimes and not others.  I sure wish that the
"network connections" thingie would push this stuff out when I click
"save", but sometimes when I go back in, what I see is *not* what I've
got.

Still working on it.  My current problem is that I can't seem to go
back to DHCP when I want to.  I need to do this to check out my
Linksys BEFSR41 DSL router; its web page appears to DHCP clients only.
 I think.

Grrrrrrr.

-- 
Kevin O'Gorman, PhD