DSL, pump, dhcp, and more questions

["Gary Hennigan" <glhenni@sandia.gov>]

So I just hooked up my ADSL connection this past weekend and it's up
and running with no problems. I am, however, having some trouble
understanding HOW it's working?!

I'm running a fresh install of potato on my firewall/masq machine
which is connected to my internal network, via a hub, and to the
external world via another ethernet adapter hooked up to a DSL
adapter. The external DSL adapters acts as a DHCP server and it's
configured and working.

Here's the extent of my understanding of the way networks get
initialized in Debian potato:

1) /sbin/ifup is called via some init script (/etc/init.d/networking?)
2) /sbin/ifup in turn reads a file, /etc/network/interfaces, which in
my case contains:

	iface lo inet loopback
	iface eth0 inet static
		address 192.168.x.x
		netmask 255.255.255.0
		network 192.168.x.x
		broadcast 192.168.x.x
	iface eth1 inet dhcp

Now I have no clue as to how ifup, for eth1, decides what dhcp client
to use? If I have both pump and dhclient installed how's it decide
what to use? Is this something that ifup decides, or is there a file
somewhere that controls this.

I had pump installed and it worked, but I read somewhere that when a
lease is renewed you should reinstall your firewall rules, and pump
couldn't do this. Is this true? I guess it makes sense if my IP were
going to change when the lease was renewed, but I don't think that'll
happen since the DSL adapter, acting as a DHCP server, only sees one
client and it assigns it an IP address of 10.0.0.2.

dhclient works just as well, but it keeps trying to do things on the
non-DHCP devices. I get gobs of messages like the following in my
logs:

dhclient-2.2.x: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
dhclient-2.2.x: DHCPDISCOVER on lo to 255.255.255.255 port 67 interval 5
dhclient-2.2.x: DHCPDISCOVER on lo to 255.255.255.255 port 67 interval 13
dhclient-2.2.x: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 10
dhclient-2.2.x: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12
dhclient-2.2.x: DHCPDISCOVER on lo to 255.255.255.255 port 67 interval 15
dhclient-2.2.x: No DHCPOFFERS received.
dhclient-2.2.x: No working leases in persistent database - sleeping.


Why? How do I keep dhclient from messing with eth0 (connected to my
192.168.x.x network with static IPs) and lo (loopback interface). The
only interface it should be playing with is eth1 (Connected to the
external DSL adapter).


Thanks for the help!
Gary