Dual NICs (wired)

[A. Jorge Garcia]

OK, I teach Computer Science at a school where the tech dept decided to put my linux classes on a separate network. So, in their infinte wisdom, they added a 2nd Network Interface Card (NIC) to each of my linux boxes (25 student stations + 1 teacher station with a projector). What's nice about this is that the new NICs are GigaBit, what's not nice is that they are going to be able to block access to other parts of the school network (b/c I have infamous hackers in my class this year).

Anyway, the problems I'm having are:
(1) how do I know which NIC is being used?
(2) how do I disable one NIC and enable another NIC when necessary?
(3) is there a configuration file where the settings from netcardconfig are saved that I can simply delete and start over?
(4) if I use netcardconfig w/o DHCP can I use any IP I feel like (I know the netmask, braodcast, default gateway and dns)?

You see, I used netcardconfig to configure eth0 as usual, but apparently, its eth1 that I should have configured as the new NIC. So, now when I run ifconfig, both NICs come up + localhost, but I don't know which is being used as default.

TIA,
AJG

[maxIT]

Anyway, the problems I'm having are:
(1) how do I know which NIC is being used?
(2) how do I disable one NIC and enable another NIC when necessary?
(3) is there a configuration file where the settings from netcardconfig are saved that I can simply delete and start over?
(4) if I use netcardconfig w/o DHCP can I use any IP I feel like (I know the netmask, braodcast, default gateway and dns)?

(1) maybe via 'ifconfig'?
(2) see answer 3 :-p
(3) see answer 4 :-p :-p
(4) the file you are looking for is (should be) '/etc/network/interfaces'
Here's mine with a 192.168.0.14 static address:

# /etc/network/interfaces -- configuration file
# The loopback interface
# automatically added when upgrading
auto lo eth0
iface lo inet loopback

iface eth0 inet static
	address 192.168.0.14
	netmask 255.255.255.0
	network 192.168.0.0
	broadcast 192.168.0.255
	gateway 192.168.0.1

The 'iface eth...' section is which that matters.
Edit the file and then issue 'update-rc.d networking defaults' to keep it persistent at every reboot.
HTH!

[A. Jorge Garcia]

Oh, thank God! Finally, the file I needed! I knew there was a config like that somewhere, I just needed someone to kickstart my memory.

Thanx, you're a God send!

Regards,
AJG

[A. Jorge Garcia]

OK, so my /etc/network/interfaces file only has

auto lo eth1
iface lo ...
iface eth1 ...
...
...
...
...
...

And all is well!

Thanx,
AJG