hard
Single Answer
0Bob needs to block Secure Shell (SSH) traffic between two security zones. Which of the following Linux iptables firewall rules will block that traffic from the 10.0.10.0/24 network to the system the rule is running on?
Answer Options
A
iptables -A INPUT -p tcp -- dport 22 -i eth0 -s 10.0.10.0/ 24 -j DROP
B
iptables -D OUTPUT -p udp - dport 21 -i eth0 -s 10.0.10 .255 -j DROP
C
iptables -A OUTPUT -p udp - - dport 22 -i eth0 -s 10.0.10 .255 -j BLOCK
D
iptables -D INPUT -p udp -- dport 21 -I eth0 -s 10.0.10.0/ 24 -j DROP
Correct Answer: A
Explanation
Even if you’re not familiar with iptables, you can read through these rules and guess which rule includes the right details. DROP makes sense for a block, and you should know that SSH will be a TCP service on port 22.