Dave and all -- Thanks for your support and helpful suggestions as I muddled through this configuration. On to the next one. The VAIO juke.

We're very close now. Removed the DSL modem and forced manual/static on external from the kubuntu system settings>network settings panel. If left on dhcp, the networking restart repopulated the 192.168.0.1 as primary, so I had to switch to static. Now, how can I make this workable?

-- From 192.168.0.9 (external lappy), I still want to ssh in to the server, so don't want to disable dhcp on the dsl modem.
-- going to set "static" assignment of ip to core/router to the mac address.
-- answering my own question, i've re-added the dsl modem to the now static configuration kubuntu for eth0, but as a _secondary_ dns. still works.

WHOOPS. The MAC authentication I remembered in the DSL modem webadmin is for wireless access allow/deny only. I'll have to set up a static routing, but don't know how to do that. Will do a bit of research to see if that is the answer. Is that how to avoid switching the kubuntu ip if the modem assigns a different ip?

Any other closing comments from the group?

Thanks again, Dave. Realizing I missed some of your first recommendations. My results tonight:

webadmin>advanced>network>network settings:
EXTERNAL_IFACE     eth0
EXTERNAL_MAC    00:XX:XX:XX:XX:0B
EXTERNAL_IP    192.168.0.5
EXTERNAL_NETMASK    255.255.255.0
EXTERNAL_DHCP    1
INTERNAL_IFACE    eth1
INTERNAL_MAC    00:XX:XX:XX:XX:24
INTERNAL_IP    192.168.80.1
INTERNAL_NETMASK    255.255.255.0
GATEWAY    192.168.0.1
DNS1    192.168.0.1
DNS2    204.[isp.primary.dns]

no errors listed in ifconfig:
eth0:           RX packets:112757 errors:0 dropped:0 overruns:0 frame:0
          TX packets:91775 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:118480264 (112.9 MB)  TX bytes:11804385 (11.2 MB)

linuxmce@dcerouter:~$ ethtool -i eth0
driver: r8169
version: 2.2LK
firmware-version:
bus-info: 0000:05:00.0

linuxmce@dcerouter:~$ sudo ethtool eth0
[sudo] password for linuxmce:
Settings for eth0:
   Supported ports: [ TP ]
   Supported link modes:   10baseT/Half 10baseT/Full
                           100baseT/Half 100baseT/Full
                           1000baseT/Full
   Supports auto-negotiation: Yes
   Advertised link modes:  10baseT/Half 10baseT/Full
                           100baseT/Half 100baseT/Full
                           1000baseT/Full
   Advertised auto-negotiation: Yes
   Speed: 100Mb/s
   Duplex: Full
   Port: Twisted Pair
   PHYAD: 0
   Transceiver: internal
   Auto-negotiation: on
   Supports Wake-on: pumbg
   Wake-on: g
   Current message level: 0x00000033 (51)
   Link detected: yes

DSL modem is an Actiontec GT701-WG  (FW 3.60.1.0.4.1)

Firewall rules.  netstat -an shows lots of binds from internal to external, so it looks like it's working. Tried disabling the firewall, but no change.
Protocol     Source Port     Destination Port     Destination IP     Rule Type     Limit to IP     
udp    4569 to 0    0       core_input       Delete
udp    5060 to 0    0       core_input       Delete
udp    2000 to 0    0       core_input       Delete
tcp    2000 to 0    0       core_input       Delete
tcp    3877 to 3877    3877    192.168.80.1    port_forward       Delete
tcp    22 to 22    22    192.168.80.1    port_forward       Delete

And late to the fray (thanks to colinjones), I tried removing the ISP as the secondary last night, and everything broke. No more Net connectivity from Internal at all. Will try removing the DSL modem as primary after I post this; will modify with my results shortly.

Thanks again for your support. I am encouraged by your additional recommendations. Be back shortly.

Ugh. Thanks to everyone for your ideas. I though I almost had it tonight. I compared a lappy on the external network to the eth0 DNS list on the core/hybrid, and realized that the secondary DNS entry on the core/hybrid was pointing at the secondary DNS for my ISP. Corrected it. I still have the DSL router listed first (192.168.0.1) and the ISP primary DNS listed second.

I also tried the DSL router power-bounce... no change.

Verified the MAC address in the client list on the DSL router's web portal for the core/hybrid. It's correct.

The core's default gateway is the DSL router (192.168.0.1) on eth0. I almost want to manually change it to the actual DSL gateway at the ISP to see what happens, but I know that won't do it.

I wonder if there is some kind of permissions issue for the linuxmce user

I'm almost at my wit's end.  =(

Dave and Mark -- Thanks very much for your input. I tried some of this and believe I have a better idea now. My lack of knowledge of ubuntu networking and conf files is the biggest stumbling block right now.

My recent progress:

basic network troubleshooting (from core/hybrid to internet):
-- bought a new ethernet cable for core/hybrid to dsl router. didn't fix it.
-- switching the internal/external cables at the core only made everything stop working. switched back.
-- ping to google is good...
linuxmce@dcerouter:~$ ping google.com
PING google.com (72.14.207.99) 56(84) bytes of data.
64 bytes from google.com (72.14.207.99): icmp_seq=1 ttl=255 time=151 ms
64 bytes from google.com (72.14.207.99): icmp_seq=2 ttl=255 time=151 ms
64 bytes from google.com (72.14.207.99): icmp_seq=3 ttl=255 time=148 ms
64 bytes from google.com (72.14.207.99): icmp_seq=4 ttl=255 time=148 ms
64 bytes from google.com (72.14.207.99): icmp_seq=5 ttl=255 time=163 ms


!! Aha! But ping to cnn is not so good...
linuxmce@dcerouter:/$ ping cnn.com
PING cnn.com (64.236.16.20) 56(84) bytes of data.
--- cnn.com ping statistics ---
12 packets transmitted, 0 received, 100% packet loss, time 11000ms

Konqueror browser shows all of google.com, but chokes on cnn.com. cnn.com shows looking up address, then connecting to server, but never gets there. I think I'm very close now. Aha! sudo /etc/init.d/networking restart yielded the following:
DHCPRELEASE on eth0 to 192.168.0.1 port 67
There is already a pid file /var/run/dhclient.eth0.pid with pid 134519120
I can get to cnn.com now, but not other addresses. Weird!
I can reach linuxmce.org, but not others. I don't get it.

arp table shows router mac for eth0 (gateway)
linuxmce@dcerouter:/$ arp -vn -H ether -i eth0 -a
? (192.168.0.1) at XX:XX:XX:XX:XX:XX [ether] on eth0
Entries: 254   Skipped: 253   Found: 1

also:
linuxmce@dcerouter:/$ cat /etc/resolv.conf
search domain.actdsltmp
nameserver 192.168.0.1
nameserver 204.[dsl isp nameserver]

Thanks again for your thoughts.
Mike

INTRODUCTION
=========
Howdy folks! -- I'm in about 3 months since my real interest in LinuxMCE; lots of research reading all your comments and watching the video over and over before I committed to get started. It's had its rough spots so far including multiple incompatible capture cards and IR remotes and gyro remote, getting a couple VAIO jukes over e-bay, and adding an additional SATA TB drive (I'll be writing an article on that later). I'm still hopeful that it'll all turn out in the end. I'm hopeful about getting it working and then helping friends do theirs; also hopeful for an iPhone 3G orbiter! This is my first post here. But enough of the introduction...


PROBLEM
======
Despite my best efforts, I cannot for the life of me get the core/hybrid itself to connect to the internet. The givens:

--2 NICs (one external, one internal);
--DHCP at DSL router is ON. I allow wireless connections to the external network,
--DHCP-enabled DSL router goes straight to the external NIC on MCE and provides a 192.168.0.x IP to eth0;
--DHCP at LinuxMCE is ON. Devices hardwired to the internal hub get their 192.168.80.x from eth1 (192.168.80.1);
--internal network does great; I attach my Ubuntu Hardy lappy to an internal hub and I can get to the Net fine.
--external network does great; I attach my WinXP lappy over wireless and reach the Net fine.

!! But, no Internet directly from the core/hybrid.

--on install eth1 was external and eth0 was internal, I used the UI to switch these and their cables.

I reverified all network settings from KDE and it makes me wonder if I have to do some kind of core/hybrid configuration so that its own apps do some kind of BIND TO ALL NICs or something?

Thanks in advance for your comments (and salutations).


P.S. Modified: my NICs:
linuxmce@dcerouter:~$ lspci | grep -i ethernet
02:00.0 Ethernet controller: Attansic Technology Corp. L1 Gigabit Ethernet Adapter (rev b0)
05:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet (rev 10)

P.P.S. Modifed: answers to first round of responses:
basic network troubleshooting (from core/hybrid to internet):
-- bought a new ethernet cable for core/hybrid to dsl router. didn't fix it.
-- switching the internal/external cables at the core only made everything stop working. switched back.
-- ping to google is good...
linuxmce@dcerouter:~$ ping google.com
PING google.com (72.14.207.99) 56(84) bytes of data.
64 bytes from google.com (72.14.207.99): icmp_seq=1 ttl=255 time=151 ms
64 bytes from google.com (72.14.207.99): icmp_seq=2 ttl=255 time=151 ms
64 bytes from google.com (72.14.207.99): icmp_seq=3 ttl=255 time=148 ms
64 bytes from google.com (72.14.207.99): icmp_seq=4 ttl=255 time=148 ms
64 bytes from google.com (72.14.207.99): icmp_seq=5 ttl=255 time=163 ms

!! Aha! But ping to cnn is not so good...
linuxmce@dcerouter:/$ ping cnn.com
PING cnn.com (64.236.16.20) 56(84) bytes of data.
--- cnn.com ping statistics ---
12 packets transmitted, 0 received, 100% packet loss, time 11000ms

Konqueror browser shows google.com, but chokes on cnn.com. cnn.com shows looking up address, then connecting to server, but never gets there. I think I'm very close now. Aha! sudo /etc/init.d/networking restart yielded the following:
DHCPRELEASE on eth0 to 192.168.0.1 port 67
There is already a pid file /var/run/dhclient.eth0.pid with pid 134519120
I can get to cnn.com now, but not other addresses. Weird!
I can reach linuxmce.org, but not others. I don't get it.


SOLUTION
========
See below for the process to reach this solution, but I had to "hard code" the ip address:
-- From the orbiter, advanced>kde desktop.
-- Then from the "K" menu at lower left, choose System Settings.
-- In kubuntu>system settings>network settings.
-- switch to administrator mode (at bottom) and enter your linuxmce password from installation.
-- Select the eth0 from the list and click [configure interface].
-- Switch from Automatic to Manual and OK.
-- Under the Domain Name Server list, moved the main DSL modem's address (in my environment 192.168.0.1) to the second position in the list. The first position shows the ISP's primary nameserver.