can't ping local 'net, even with no firewall

[Matthew Garman <garman@uiuc.edu>]

I have an internal LAN with two computers.  Even with no firewall, I can't
get the two computers to ping each other.  For example, do the following
to flush all iptables:

	iptables -F
	iptables -t filter -F INPUT
	iptables -t filter -F OUTPUT
	iptables -t filter -F FORWARD
	iptables -t nat -F
	iptables -t nat -F PREROUTING
	iptables -t nat -F POSTROUTING
	iptables -t nat -F OUTPUT
	iptables -t mangle -F
	iptables -t mangle -F PREROUTING
	iptables -t mangle -F OUTPUT

Now I set all default policies to ACCEPT:

	iptables -P INPUT ACCEPT
	iptables -P OUTPUT ACCEPT
	iptables -P FORWARD ACCEPT
	iptables -t nat -P PREROUTING ACCEPT
	iptables -t nat -P POSTROUTING ACCEPT
	iptables -t nat -P OUTPUT ACCEPT
	iptables -t mangle -P OUTPUT ACCEPT
	iptables -t mangle -P PREROUTING ACCEPT

And still the two computers can't ping each other.  When I try to ping, I
watch the lights on my switch: the lights for both computers are flashing,
indicating link activity, but still ping times out.

On my computer, which has the Internet connection, I can ping any host out
on the internet.

Any thoughts?

Thanks,
Matt

-- 
Matt Garman, garman@uiuc.edu
"I'll tip my hat to the new constitution, Take a bow for the new revolution
 Smile and grin at the change all around, Pick up my guitar and play
 Just like yesterday, Then I'll get on my knees and pray..."
            -- Pete Townshend/The Who, "Won't Get Fooled Again"