Thanks for all, This is the simplest way of my iptables, But now I can't also get internet windows xp to external windows xp.After i run iptables ,Save like that # service iptables save
I have done all of your ieda, still can't get netmeeting ...... >>

# Generated by iptables-save v1.2.11 on Tue Jan 17 13:56:40 2006
*filter
:INPUT ACCEPT [4725:2869978]
:FORWARD ACCEPT [127:39118]
:OUTPUT ACCEPT [2641:2333465]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -p tcp -m tcp ! --tcp-flags SYN,RST,ACK SYN -j ACCEPT
-A INPUT -p udp -m udp --dport 10200:10209 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 10200:10209 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 1720 -j ACCEPT
COMMIT
# Completed on Tue Jan 17 13:56:40 2006
# Generated by iptables-save v1.2.11 on Tue Jan 17 13:56:40 2006
*nat
:PREROUTING ACCEPT [972:121081]
:POSTROUTING ACCEPT [231:26401]
:OUTPUT ACCEPT [231:26401]
-A PREROUTING -p tcp -m tcp --dport 1720 -j REDIRECT
-A POSTROUTING -s 10.0.0.0/255.0.0.0 -o eth0 -j MASQUERADE
COMMIT
# Completed on Tue Jan 17 13:56:40 2006

I made a call from external xp to Fedora Core 3's external ip .. to forward or redirect .. ... internal windows xp.
thanks all
Berkeley