Nope, it's not working for you. All ifconfig displays is your loopback.
First we'll find out if any interfaces are found and recognized:
It should gine at least interface 'lo', but what we are looking for is one named similar to 'eth0' 'eth1'
Maybe it's just a question of bringing up the interface (although I doubt it, but it's worth a shot)
Code:
/sbin/ifconfig eth0 up
where eth0 should be replaced with the name of the interface you found in the previous command.
And then:
Any errors? Does your eth* interface get listed now?
If no errors and the device shows up, can you ping your router? Can you see whether you have an IP address now?
--if not--
Check to see whether in /etc/rc.d/ the following files are executable:
rc.inetd
rc.inet1
Post here if this is not the case
Do you use DHCP or a static address? How did you configure it during setup?
dmesg output may not be of much use here, unless this shows up with errors:
Again, eth0 should be replaced with the name of the interface you found in the first command.
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As for your other question about upgrading rather than doing a clean install, read at least these documents:
changes and hints upgrade