What will be the result of running sudo iptables -A INPUT -p tcp --dport 443 -j ACCEPT followed by sudo iptables -L?

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Linux CLI - System Administration

What will be the result of running sudo iptables -A INPUT -p tcp --dport 443 -j ACCEPT followed by sudo iptables -L?

AThe rule will delete existing rules on port 443

BA rule allowing TCP traffic on port 443 will be added to the INPUT chain

CAn error will occur because <code>-A</code> is invalid

DA rule blocking TCP traffic on port 443 will be added to the OUTPUT chain

Step-by-Step Solution

Solution:

Step 1: Analyze the iptables command
-A INPUT appends a rule to the INPUT chain; -p tcp --dport 443 matches TCP traffic on port 443; -j ACCEPT accepts matching packets.
Step 2: Check expected output of iptables -L
The new rule will appear in the INPUT chain allowing TCP port 443 traffic.
Final Answer:
A rule allowing TCP traffic on port 443 will be added to the INPUT chain -> Option B
Quick Check:
iptables -A INPUT adds accept rule for TCP port 443 [OK]

Quick Trick: Append rules with -A to INPUT chain for incoming traffic [OK]

Common Mistakes:

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