eth0 - eth1 confusion vs. local network

[Frank Miles <fpm@u.washington.edu>]

I am in the final throes of getting a new system running (Debian/squeeze).
For the past 2 weeks it's had just eth0, and the network has worked fine.
Now I want this system to have two network interfaces - the original eth0, 
and eth1 to a DSL modem, just like its precessor system.

The strange thing is that wth the introduction of the second network card,
the DSL connection works fine, but eth0 fails.

A few relevant outputs: first, ifconfig shows (I masked the HWaddr's):

  eth0    Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx
          inet addr:192.168.0.10  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::6ef0:49ff:fe08:a40/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:198 errors:0 dropped:0 overruns:0 frame:0
          TX packets:26 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:11880 (11.6 KiB)  TX bytes:1916 (1.8 KiB)
          Interrupt:32 Base address:0x2000

  eth1    Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx
          inet addr:192.168.1.33  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::260:8ff:fead:ec57/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:5811 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6876 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:4123103 (3.9 MiB)  TX bytes:740692 (723.3 KiB)
          Interrupt:18 Base address:0xdf00

  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:212 errors:0 dropped:0 overruns:0 frame:0
          TX packets:212 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:43609 (42.5 KiB)  TX bytes:43609 (42.5 KiB)

And route -n :
  Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
  192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
  192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
  0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth1


However, if I (even as root) try to ping another machine on the network:
	PING 192.168.0.4 (192.168.0.4) 56(84) bytes of data.
	ping: sendmsg: Operation not permitted
	ping: sendmsg: Operation not permitted
	...

ssh to the other machine similarly fails, though it worked when the new machine
had a single interface.  Similarly, I cannot ping or otherwise interact with
the new machine from other machines on the local network.

Strangely, arp -a shows:
	grebe (192.168.0.4) at xx:xx:xx:xx:xx:xx [ether] on eth0
	rubberducky (192.168.1.1) at xx:xx:xx:xx:xx:xx [ether] on eth1
where 'grebe' is the machine that I tried to ping.  It may have gotten the
name from /etc/hosts, not necessarily via the network.

No help if iptables rules are flushed.

There is one troubling line in the logs from boot:
	udev: renamed network interface eth0 to eth1
Doing an "ifdown eth1" does not fix the eth0 problem.

So far, I haven't seen anything in the udev rules that might cause this.

This is all with the 2.6.32-trunk kernel in squeeze.

If anyone has any ideas on how to diagnose or fix this problem I'd
appreciate it.  TIA!

	-F