Dear Friends: I have observe a behavior of iptables which I need to understand. 216.155.193.168 is the IP address of Yahoo's messenger site and it listens on port 5050. The following command will allows the machine to connect to 216.155.193.168. iptables -A OUTPUT -o eth0 -p tcp -d 216.155.193.168 --dport 5050 -j ACCEPT After that, I see output like following: #telnet 216.155.193.168 5050 Trying 216.155.193.168... Connected to 216.155.193.168. Escape character is '^]'. Now when I issue iptables -A OUTPUT -o eth0 -p tcp -d 216.155.193.168 --dport 5050 -j DROP And iptables -A OUTPUT -o eth0 -p tcp -d 216.155.193.168 --dport 5050 -j REJECT Still, it allows connection to 216.155.193.168 on port 5050. How does this work? It seems -j DROP is not opposite of -j ACCEPT. How can stop this? Kind regards. Ravi Verma
