[gentoo-user] Trying to block third party ip address with iptables...

[pk]

Hello,

I am using shorewall on my local computer (the same I'm surfing the web 
with). My skills with iptables are not really good and my understanding 
of networking also has some holes in it... However, I'm trying to 
prevent firefox from accessing a third party site; I'm logging onto a 
site with firefox. With netstat I can see that besides the usual ip 
address belonging to the site another ip-address (not belonging to the 
original site) shows up. While trying to block the additional ip address 
with both "iptables -A INPUT -s xxxx -j DROP" and "iptables -A OUTPUT -d 
xxxx -j DROP" it still sends a SYN request to this site. This makes 
firefox just sit there waiting for a time-out. How can I prevent firefox 
from accessing the other site, while still accessing the original one?

Best regards

Peter K