Firewall, ping and nmap

[getting_out <getting_out () tele2 it>]

Good morning.

I have a debian woody on witch I've configured a firewall (iptables) 
with the following rules

$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination
block      all  --  anywhere             anywhere

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
block      all  --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain block (2 references)
target  prot opt source    destination
ACCEPT  all  --  anywhere  anywhere    state RELATED,ESTABLISHED
REJECT  all  --  anywhere  anywhere    reject-with icmp-port-unreachable

If I'm connected on the internet, via modem (ppp0), I can do a ping and 
get responses from hosts. If I'm connected in a LAN, and do a ping, I 
don't receive any response unless I shut down the firewall (iptables -F).

With npam, instead I must always shut down the firewall.

Can anyone enlighten me?

thanks and bye

Dvd (<-- It's for David :))

PS: please, forgive my English



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