I'm running Postfix SMTP server. Some hosts trying to connect with wrong passwords.warning: s15393678.onlinehome-server.com[74.208.17.126]: SASL LOGIN authentication failed: I'm adding iptables rule on the the fly to block this IP:iptables -A INPUT -s 74.208.17.126 -j DROPBut it still this host gets connected. I still see in logs this host.  What might be wrong?iptables -LDROP       all  --  s15393678.onlinehome-server.com  anywhere
IPtables don't block IP
linux;iptables
You probably want -I INPUT instead of -A INPUT.-A INPUT is going to add the rule to the bottom of the chain. Meaning that if you have something like -p tcp --dport 25 -j ACCEPT before it, the ACCEPT is going to match first, and the processing will never get to your -j DROP rule.The -I INPUT will add the rule to the top, so it overrides everything else.