You Want to Configure Your Linux Firewall to Block All

Multiple Choice

You want to configure your Linux firewall to block all network traffic addressed to the Telnet service on the local system. Which of the following commands should you use?

A) iptables -t filter -A INPUT -s 0/0 -p tcp -dport 23 -j DROP
B) iptables -t filter -A OUTPUT -s 0/0 -p tcp -dport 23 -j DROP
C) iptables -t filter -A INPUT -s 0/0 -p tcp -dport 80 -j DROP
D) iptables -t filter -A INPUT -s 0/0 -p tcp -dport 53 -j ACCEPT